OptimumK Help File

OptimumK Help 1.1 Copyright © 2008 OptimumG LLC. All Rights Reserved. 1

HELP FILE


Table of Contents

Welcome 6

Introduction 8

Installation Requirements 9

License 10

Project Files 11

Reference System 12

Axis 13

Units 17

Reference Distance 19

Design 20

Design Section Overview 21

Design Section Layout 22

Create New Design 27

Inputs

Front Suspensions

Double A-Arm

A-Arm Points 32

Steering

Steering Types 35

Rack & Pinion 36

Recirculating-Ball 37

Wheel Geometry 39

Anti-Roll Bar

Anti Roll Bar Types 44

U-Bar 45

U-Bar with Rocker 46

T-Bar 48

T-Bar Monoshock 49

T-Bar with 3rd Spring 50

Spring Actuation

Actuation Types 53

Direct Actuation 54

Push-Pull Actuation 55

Separate Spring & Damper 57

Monoshock Rotational Actuation 58

Monoshock Sliding Actuation 60

Torsion Bar 62

Mac Pherson

Mac Pherson Points 65

Steering


Steering Types 67

Rack & Pinion 68

Recirculating -Ball 69

Wheel Geometry 71

Spring 75

Anti-Roll Bar 76

Mac Pherson Pivot Arm

Mac Pherson Pivot Arm Points 78

Steering

Steering Types 81

Rack & Pinion 82

Recirculating -Ball 83

Wheel Geometry 85

Spring 89

Anti-Roll Bar 90

Nascar

Control Arms 92

Steering 94

Wheel Geometry 96

Spring & Shock 100

Sway Bar 101

Rear Suspensions

Double A-Arm

A-Arm Points 104

Tie Rod 106

Wheel Geometry 107

Anti-Roll Bar


U-Bar 113


T-Bar 116

T-Bar Monoshock 118

T-Bar with 3rd Spring 119

Spring Actuation

Spring Actuation Types 122

Direct Actuation 123





Torsion Bar 132

Five Links

Link Points 135

Wheel Geometry 137

Anti-Roll Bar


U-Bar 143


T-Bar 146

T-Bar Monoshock 147


Spring Actuation

Spring Actuation Types 149

Direct Actuation 150





Mac Pherson

Wish & Strut 160

Tie Rod 162

Wheel Geometry 163

Spring 167

Anti-Roll Bar 168

V8 Supercar

Trailing Arm Points 171

Watts Linkage 173

Wheel Geometry 174

Spring 178

Anti-Roll Bar


U-Bar 181


NASCAR

Truck Arms 185

Track Bar 186

Wheel Geometry 187

Spring & Shock 191

Reference Points 193

Design Comments 194

Import-Export Design 195

Motion 197

Motion Overview 198

Motion Section Layout 199

Motion Types

Roll 204

Pitch 207

Heave 209

Steering 211

Create New Motion 214

Motion Graphs 216

Import & Export Motion 219

Simulator 222

Simulator Overview 223

Simulator Toolbar 224

Add Design 225

Add Motion 226

Simulator Preferences 227

Run Simulation 229


Batch Run 230

Analysis 232

Analysis Overview 233

Analysis Section Layout 234

Create New Analysis 240

Analysis Tools

Graph Tool 243

Report Tool 247

Animation Tool 250

Output Data Tool 253

Overlay Simulation Data 255

Export Analysis 257

Output Channels 259

Motion 259

Points 260

Link Lengths 261

Wheel 263

Upright 267

Axis

Instant Axis 269

Swing Arms 270

Roll & Pitch Axis 271

Colinearity of Front and Rear Roll Axes 273

Actuation 274

Anti-Roll Bar 277

Steering 279

Motion Ratio

Wheel 281

Roll 283

Heave 285

Suspension Design Tips 287

Wheelbase and Tracks 288

Wheel Packaging 291

KPI and Caster 292

Roll Axis 295

Lateral VSAL 297

Pitch Axis 298

Bump Steer 300

Ackermann 301

Feedback 302


Welcome

Thank you for purchasing OptimumK the new benchmark in kinematics analysis. This help file contains information about all the functions and features of OptimumK. Included in this help file are

• Information about all the functions and features of OptimumK

• Tutorial Video

• PDF version of the help file

• Frequently Asked Questions

• Explanation of outputs

• Tips and tricks on how to optimize a suspension’s kinematics

Learning OptimumK The tutorial video is designed to give users a basic understanding of the OptimumK software. It is recommended

that users read through the help file in order to get a complete understanding of the software.

Feedback OptimumK is a continually developing program and we give high regard to any suggestions, comments, complaints

or criticisms that OptimumK users might have. Please contact us at [email protected] and we will

endeavor to improve OptimumK based on your feedback.

Features Coming Soon The following is a list of features that will be available in future updates. Updates will be free to download for users

who have already have purchased OptimumK.

• Separate Spring and Damper for Push-Pull Rod spring actuation type

• 3D Graphs

• Selectable points in 3D animation

• Chassis shown in 3D animation

• Mode to design suspension using Swing Arm Lengths and Instant Center Heights

• Enter Your Suggestions Here

Forced Based Add-On (Coming Soon)

The Forced based add-on includes features such as; • Forced based Roll and Pitch center

• Spring and Tire and Anti-Roll Bar stiffness

• Spring, Anti-Roll Bar Loads

• Anti-Roll and Pitch distribution

• Tire Model


Nascar Setup Add-On (Coming Soon)

This add-on is specifically designed for a Nascar suspension and allows user to; • Import Individual A-Arms, Spindles and Chassis into OptimumK

• Modify pickup point locations using Shims and Slugs

• Export manufacturing drawings of suspension parts


Introduction

Why OptimumK?

OptimumK is harnessed from OptimumG’s vast knowledge and experience in measuring, designing and modifying vehicle suspension systems. It features ground-breaking capabilities in computational suspension analysis, such as

the ability to simultaneously define Roll, Pitch, Heave and Steering motions. It features real-time 3D graphic visualization that allows the user to observe these combined motions in detail, including the effects of critical

dependant parameters such as Pitch and Roll Center migration.

OptimumK provides an easy-to-use graphical interface for designing common suspension systems. The 3D graphic

output window allows the user to visualize the suspension geometry as the coordinates are inputted into the design tables. In addition, users are able to define multiple front and rear suspension geometries in each project, and

compare various setups using graph overlays. Similarly, users are also able to store multiple vehicle motion profiles

and analysis sheets in the same project file. This allows the user to quickly determine the changes based on various factors such as bump-steer, Ackermann angles, roll center heights, etc.

Finally, OptimumK includes a powerful feature that allows the user to easily import data from leading data

acquisition systems. This data can then be used to replay the suspension movements on screen, and to perform

many other kinematical analyses.

The Goal of OptimumK

The following are the principal objectives of OptimumK:

• Allow users to quickly analyze suspension parameters from paper to screen

• To serve as an educational tool for both the novice and advance user

• Greatly reduce development and testing time for race teams

• Enable faster and better quantitative decisions with regards to setup changes

• Provide comprehensive after-sales support to teams, with the backing of OptimumG’s vast knowledge

in vehicle dynamics


Installation Requirements

Hardware Requirements

Processor • Intel® Pentium 4™, Intel® Xeon™, and Intel® Core™.

• AMD® Athlon™, AMD® Opteron™, and AMD® Turion™

Memory • Minimum: 512MB RAM

• Recommended: 1GB RAM or more

• Virtual Memory recommended to be twice the amount of RAM

Storage

• Free space of al least 100MB. Includes installation of OptimumK® and required software components (see

below)

Display Adapter • Minimum: Microsoft® DirectX® 9.0c capable graphics card with 32MB RAM

• Recommended: DirectX® 9.0c capable NVIDIA® GeForce® or ATI® Radeon® with 128MB RAM or higher

Display Unit

• Minimum: 15” Screen with resolution of 1024 x 768 pixels

• Recommended: 19” Screen with resolution of 1280 x 1024 pixels

Other

• Mouse or other pointing device

• CD or DVD drive

Software Requirements

Operating System • Microsoft® Windows® XP (32 or 64bit) or Microsoft® Windows® Vista (32 or 64bit)

Required Software Components • Microsoft® .NET® Framework 2.0 or higher

• Microsoft® DirectX® 9.0c or higher

Other • Microsoft® Excel™ version 10 or higher for import or export of data

• Internet Explorer™ 6 or higher for viewing the online help documentation


License

[Page Name]

An OptimumK license has no time expiration period and it can only be used on one computer.

Moving License

If the license needs to be moved to another computer it can be done from within OptimumK. To deactivate a license

your computer will need an internet connection.

To move a license to another computer;

1. Launch OptimumK.

2. From the project screen select the Help menu and click Deactivate License.

3. Click yes in the Deactivate License message box.

4. Click Deactivate in the Web Activation message box.

The “Online Deactivation was successful” message box will appear once the license has been deactivated. OptimumK

can know be installed on another computer using the same license key.


Project Files

OptimumK project files end with the file extension .OPr. All the data pertaining to a project created in OptimumK is

consolidated and stored in a single .OPr file. This allows the user to easily transport project files amongst different

computers.

The following data is contained in a project file: • Suspension design configurations and coordinates

• Motion data and graphs

• Simulation data

• Data Channel Reports and Graphs.

The size of a project file varies greatly depending on quantity of the above-mentioned data. The project file is stored

in binary format. To prevent file corruption, no attempts should be made to open or edit the project file in a text-editor, such as Notepad.

When OptimumK is loaded the project screen appears. From the project screen the user can select to open an

existing project or create a new project.


Reference System


Reference System/Axis

OptimumK uses three axes to define the coordinates of the suspension points • Longitudinal Axis – Points to the forward or backward directions of the car.

• Lateral Axis – Points to the left or right hand side of the car.

• Vertical Axis – Points vertically up or down.

The user can define which of the three axes is labeled X, Y and Z. This feature enables easy integration into a CAD

package. OptimumK is also able to design a suspension using one reference axis system and then output the results

of a simulation using a different reference axis system

Input Reference Axis

Change the input reference axis;

1. From within the design section select the Options menu button from the Input Toolbar.

2. Select Referential.

3. Select the direction of the X, Y and Z axes.


Each design item in a project can have its own individual input reference axis. The input reference axis is exported with a design. When a design is imported back into OptimumK the reference axis will update automatically based on

the reference axis that was used when the design was originally exported.

Upright Reference

All points that are on the upright can be referenced from either the chassis origin (origin used for all other points) or

a user defined Upright Origin.

To reference upright points from the Upright Origin;


2. Select Referential.

3. Un-check the Use Chassis Origin check box.

4. Enter the Coordinates of the left and right Upright Origins

5. Enter the Upright Origin Name (e.g. Wheel mounting flange)

All points that are on the upright are now referenced from the Upright Origin. The points that are referenced from

the Upright Origin are displayed with red text in the Input Window.


Wheel Reference

The Options in the Referential Window allow the location of the contact patch to be referenced from either the Chassis or Upright Origin. The half track can also be measured from either the contact patch or wheel center.

Simulation Output Reference Axis

Change the output reference axis;

1. Click the Simulator Preferences button in the Program Toolbar.

2. Select the Output Tab.

3. Select the direction of the X, Y and Z axes from within the Referential Axis section.

The selected output reference axis is used for all Simulations in the Analysis section.


Angular Displacement

Positive Roll – Clockwise rotation about the Roll Axis. (When viewed from behind vehicle)

Positive Pitch – Anti-clockwise rotation about the Pitch Axis. (When viewed from left of vehicle)

Positive Yaw – Anti-clockwise rotation around the Center of Gravity. (When viewed from above vehicle)

Motion Sign Convention


Positive Pitch – Anti-Clockwise rotation about the Pitch Axis. (When viewed from left of vehicle)

Positive Heave – Vertically up.

Positive Steering – Wheels turn to the Left. (When viewed from above vehicle)


Reference System/Units

OptimumK is able to use both imperial and metric units. The user can also input dimensions in imperial units and

then have the results calculated and displayed in metric units and vise versa.

Input Units

Change input units;


2. Select Units.

3. Select the Desired Units (in or mm).

The current input units will be displayed in brackets on the options menu button in the Input Toolbar. Each design

item in a project can have its own individual units.

Output Units

Change output units;

1. Click the Simulator Preferences button in the Program Toolbar.

2. Select the Output tab.

3. Select the desired distance and angle units from within the units section.


The currently selected output units are displayed in the bottom left hand corner of the screen. These units are used

for all the Simulations in the Analysis section.


Reference System/Reference Distance

The reference distance is the distance between the front reference plane and the rear reference plane. It is NOT

necessarily the wheelbase.

The front reference plane is where the longitudinal coordinates of all the front suspension points are measured from. This plane can be anywhere the user wants to measure the points from. (E.g. front spoiler, vehicle origin in CAD,

wheel center line etc.). The distance from the center of the front contact patches to the front reference plane is

called Long. Offset this distance is defined in the wheel geometry section of a design.

The rear reference plane is where the longitudinal coordinates of all the rear suspension points are measured from. This plane can be anywhere the user wants to measure the points from. (E.g. front spoiler, vehicle origin in CAD

system, wheel center line etc.). The distance from the center of the rear contact patches to the rear reference plane

is called Long. Offset this distance is defined in the wheel geometry section of a design.

OptimumK uses reference distance instead of defining a wheelbase because some oval track race cars have different wheelbases on the left and right hand sides of the car.


Design


Design/Design Section Overview

The design section of OptimumK is where the suspension gets built. All the pickup points for the control arms,

steering system, tie rods, wheels, uprights, springs, dampers and Anti-Roll Bars are defined in the design section.

OptimumK also displays a 3D animation of the current suspension to aid the design process.

A powerful feature of OptimumK is its ability to create and store multiple designs. This enables the user to save

many design iterations of a suspension for easy comparison.

OptimumK currently allows the user to design a suspension using the following suspension types.

Front Suspension Types

• Double A-Arm

• Mac Pherson

• Mac Pherson Pivot Arm (Used in Renault Clio and Megane)

• Nascar (Dedicated Nascar Suspension)

Rear Suspension Types

• Double A-Arm

• Mac Pherson

• V8 Supercar (Dedicated V8 Supercar Suspension)

• Nascar (Dedicated Nascar Suspension)

• Five Links

If you require a suspension type that is not listed here please Contact Us.


Design/Design Section Layout

Design Tree Window

The design tree window displays all the design items that the user creates. These design items can be stored in folders to assist with organization during the suspension design process.


Design Tree Toolbar

New Folder – Creates a folder in the design tree.

New Item – Creates a new design item in the design tree.

Delete – Deletes the selected design item.

Add to Simulator – Adds the selected design item to the simulator.

Input Window

The input window is where the suspension’s geometrical coordinates are entered. To assist the designer there are a number of different ways to view the input window.


Input Toolbar

Input Summary – Displays all the suspensions input values.

Component Inputs – Displays the input values of one particular suspension component.

Options Menu – Displays a menu where the user can Import or Export a suspension design, define the suspensions Input Units, alter the Reference Axis or change the color of the suspension components.


Symmetry Check Box – When checked an entered input value will be automatically reproduced on the opposite

side of the suspension.

Display Window

The display Window displays a 3D graphical representation of the currently selected suspension design.


View Orientation Toolbar

Translate View - Scrolls the suspension geometry across the display window.

Rotate View - Rotates the suspension geometry view about a point.

Zoom - Dynamically changes the scale of the suspension geometry.

Zoom to Selected Area - Zooms into an area that is selected by dragging a bounding box.

Transparent View - Changes the opacity of the tires.

Parallel/Perspective –Toggles the 3D graphical representation between parallel and perspective image distortion.

Standard Views – Rotates the display to front, back, right, left, top or bottom view.

Rotate View 18deg – Rotates the suspension by 18 degrees to the left, right, up or down.

Background Color – Changes the background gradient to a user selected color.


Design/Create New Design

All the pickup points for the control arms, steering system, tie rods, wheels, uprights, springs, dampers and Anti-Roll Bars are stored in a design item. These design items are displayed in the Design Tree.

Create New Design Item

To create a new Design Item;

1. Select the New Item button from the Design Tree Toolbar.

2. Select the Suspension Type.

3. Click Go To Design.

The newly created design item will be displayed in the Design Tree. If the design item is a front suspension,

“[Front]” will automatically be inserted into the design item name and the design item icon will have its front wheels highlighted green. For a rear suspension, “[Rear]” will automatically be inserted into the design item name and the

design item icon will have its rear wheels highlighted green.

Design Item Right-Click Options

The following options can be accessed by right-clicking on a Design Item or folder in the design tree.

New Folder – Adds a new folder to the design tree.

New Item – Adds a new design item to the design tree.

Delete – Deletes the currently selected design item.

Rename – Highlights the design item or folder name so that it can be renamed.

Cut – Deletes and copies the design item or folder to the clipboard.

Copy – Copies the design item or folder to the clipboard.

Paste – Pastes the design item or folder that is currently in the clipboard into the design tree.


Design Suspension

Input Values;

1. Select a Design Item from the Design Tree.

2. Click the Input Summary button on the Input Toolbar.

3. Input the Suspension Coordinates into the appropriate editable text boxes.

The orientation of X,Y and Z coordinateness are defined by the Reference System. Further explanation of each individual input can be found in the Coordinate Inputs section of the help file.

A value that is inputted into a Left box will automatically be entered into the opposite Right box when symmetry is

selected and vice versa.

Suspension component inputs can be view independently by selecting the desired suspension component from the

Component Inputs Menu on the Input Toolbar.

As the suspension coordinates are entered the suspension will build automatically in the Display Window.


Design/Inputs

Front Suspensions

Rear Suspensions


Design/Inputs/Front Suspensions


Design/Inputs/Front Suspensions/Double A-Arm

A-Arm Points Steering

Wheel Geometry

Anti-Roll Bar Spring Actuation


Design/Inputs/Front Suspensions/Double A-Arm/A-Arm Points

The most common form of suspension type is Double A-Arms. A Double A-Arm suspension consists of two “A”

shaped Arms each of which has two points connected to the chassis and one point connected to the upright.

To Edit the A-Arm Geometry;

1. Select the Suspension Design Item that you want to edit the A-Arms of.

2. Click Summary to display the Input Summary Window.

3. Scroll to the A-Arm section.

4. Enter Values

Lower Arm – Chassis Fore

This is the point where the leading point of the Lower A-Arm connects to the Chassis.

Lower Arm – Chassis Aft


This is the point where the trailing point of the Lower A-Arm connects to the Chassis.

Lower Arm – Upright

This is the point where the Lower A-Arm connects to the Upright.

Upper Arm – Chassis Fore

This is the point where the leading point of the Upper A-Arm connects to the chassis..

Upper Arm – Chassis Aft

This is the point where the trailing point of the Upper A-Arm connects to the Chassis.

Upper Arm – Upright

This is the point where the Upper A-Arm connects to the Upright.


Design/Inputs/Front Suspensions/Double A-Arm/Steering


Design/Inputs/Front Suspensions/Double A-Arm/Steering/Steering Types

OptimumK currently has two steering types for Double A-Arm suspensions. Rack and Pinion is the most common

type of steering. Recirculating-Ball steering is used in some oval track racing series and classic production cars.

To Edit the Steering Geometry;

1. Select the Suspension Design Item that you want to edit the steering of.


3. Scroll down to the steering type section.

4. Select the desired Steering Type from the drop down list.

a. Rack and Pinion

b. Recirculating-ball Steering

5. Enter values


Design/Inputs/Front Suspensions/Double A-Arm/Steering/Rack & Pinion

Rack and Pinion type steering is comprised of a toothed Rack that is moved sideways by a rotating Pinion which is connected to the steering wheel. Two Tie Rods are connected from the ends of the Rack to the Uprights.

Tie Rods – Rack

This is the point where the Tie Rod connects to the end of the Steering Rack

Tie Rods – Upright

This is the point where the Tie Rod connects to the Upright.

Steering Rack Displacement/Steering Wheel Revolution

This is the amount of rack displacement (in millimeters or inches) when the steering wheel is rotated 360 degrees.


Design/Inputs/Front Suspensions/Double A-Arm/Steering/Recirculating-Ball

Recirculating-Ball type steering is comprised of a Center Link that is rotated about a point on the Chassis when the steering wheel is turned. Two Tie Rods are connected form the Center Link to the Uprights.




Tie Rods – Center Link

This is the point where the Tie Rod connects to the Center Link

Pitman Arm – Chassis

This is the point where the Pitman Arm connects to the Chassis

Pitman Arm – Axis

This point (along with the Pitman Arm – Chassis point) defines the axis that the Pitman Arm rotates around

Pitman Arm – Center Link

This is the point where the Pitman Arm connects to the Center Link

Idler Arm – Chassis

This is the point where the Idler Arm connects to the Chassis

Idler Arm – Center Link

This is the point where the Idler Arm connects to the Center Link

Steering Wheel Angle/Degree of Pitman Arm

This is the angular displacement of the steering wheel for one degree of pitman arm rotation.


Design/Inputs/Front Suspensions/Double A-Arm/Wheel Geometry

The Wheel Geometry section is where all the wheel related inputs are entered. Such as track, offset, camber, toe,

rim and tire dimensions.

To input or modify the wheel geometry;

1. Select the Suspension Design Item that you want to modify the wheel geometry of.

2. Click the Summary button to display the Input Summary Window.

3. Scroll down to the Wheel Geometry section.

4. Enter values.

Half Track

The Half Track is the horizontal distance from the center of the tire contact patch to the longitudinal axis.

Long. Offset

The Long. Offset (Abbreviation of Longitudinal Offset) is the distance from a plane located perpendicular to the

longitudinal axis to the suspensions origin. Long. Offset can be used when the suspension coordinates are not

measured form the origin but another location.


Vertical Offset

The Vertical Offset is the distance from the contact patch to the ground. A positive offset will place the contact patch

above the ground while a negative offset will place the contact patch below the ground. Vertical Offset can be used when the suspension coordinates are not referenced form the ground plane but another location.

Static Camber

Static camber is the angle between the wheel plane and the vertical, while the car is in a stationary position. Negative camber is defined as the wheel plane being tilted towards the center of the vehicle. While positive camber

is defined as the wheel plane being tilted away from the center of the vehicle.


Static Toe

Static toe is the angle between the wheel plane and the longitudinal axis of the vehicle. Positive toe (toe out) is

when the front of the wheels are steered outwards while negative toe (toe in) is when the front of the wheels are

steered inwards.


Rim Diameter

The Rim Diameter is the diameter of the rim edge not the tire bead seat. This is used as a reference point to

measure toe distance.

Tire Diameter

The Tire Diameter is the outside diameter of the tire. The user can choose to use either the unloaded, loaded or

rolling diameter of the tire

Tire Width

The Tire Width is the overall width of the tire. OptimumK models the tire as an un-deformable disc so this dimension

is not used in the calculation. The tire width is only used in the 3D display and to define the wheel axis in the output

section


Design/Inputs/Front Suspensions/Double A-Arm/Anti-Roll Bar


Design/Inputs/Front Suspensions/Double A-Arm/Anti-Roll Bar/Anti Roll Bar Types

OptimumK currently has four Anti Roll-Bar types for Double A-Arm suspensions. Each of these Anti-Roll Bars has

different packaging and functional requirements making them suitable to different types of vehicles.

To Insert an Anti-Roll Bar;

1. Select the Suspension Design Item that you want to add the Anti-Roll Bar to.


3. Scroll down to the Anti-Roll Bar type section.

4. Select the desired Anti-Roll Bar Type from the drop down list.

• U-Bar

• U-Bar with Intermediate Rocker

• T-Bar

• T-Bar for Monoshock

• T-Bar with Third Spring

5. Enter Values


Design/Inputs/Front Suspensions/Double A-Arm/Anti-Roll Bar/U-Bar

A U-Bar type Anti-Roll Bar is comprised of two Lever Arms mounted to the Anti-Roll Bar Shaft (also known as working length). The shaft is mounted to the chassis in a manner that allows the Anti-Roll bar to rotate freely

forward and backward in the car. Two drop links are connected from the Lever Arm ends to the Upper A-Arm, Lower

A-Arm, Rocker or Upright.

Pivot – Chassis Pivot

This is the point where the Shaft is mounted to the Chassis.

Attachment

This drop down list gives a list of suspension components that the Anti-Roll Bar can be attached to. For a Double A-

Arm suspension the U-Bar type Anti-Roll Bar can be attached to the, Upper A-Arm, Lower A-Arm, Rocker or Upright.

Drop Link – Anti Roll Bar

This point is where the Drop Link attaches to the Lever Arm

Drop Link – Attachment

This point is where the Drop Link attaches to the suspension component displayed in the attachment drop down list.


Design/Inputs/Front Suspensions/Double A-Arm/Anti-Roll Bar/U-Bar + Rocker

A U-Bar with Intermediate Rocker type Anti-Roll Bar is comprised of two Lever Arms mounted to the Anti-Roll Bar Shaft (also known as working length). The Shaft is mounted to the chassis in a manner that allows the Anti Roll bar

to rotate freely forward and backward in the car. Two Drop Links are connected from the Lever Arm ends to a set of

Intermediate Rockers. Another two Drop Links are then connected from the Rocker to the Upper A-Arm, Lower A-Arm or the Upright.




Drop Link from U-Bar – Anti Roll Bar

This point is where the Drop Link attaches to the Lever Arm.

Drop Link from U-Bar – Rocker

This point is where the Drop Link attaches to the Rocker.

Rocker - Pivot

The axis that the rocker rotates a about is defined by the Rocker Pivot and Axis points. The Rocker Pivot point is where the Rocker Axis is located on the Rocker.

Rocker – Axis Point

The Rocker Axis point is the second point that defines the Rockers rotational axis.

Attachment


Arm suspension the U-Bar with Intermediate Rocker type Anti-Roll Bar can be attached to the Upper A-Arm, Lower A-Arm, Rocker or Upright.

Drop Link from Rocker – Rocker


Drop Link from Rocker – Attachment



Design/Inputs/Front Suspensions/Double A-Arm/Anti-Roll Bar/T-Bar

A T-Bar type Anti-Roll Bar is comprised of a Lever Arm mounted perpendicular to the Anti-Roll Bar Shaft (also known as working length). A Chassis Pivot is mounted perpendicular to the base of the Shaft. The Chassis Pivot is mounted

to the chassis in a manner that allows the Anti-Roll Bar to rotate freely forward and backward in the car. Two Drop

Links are connected from the Lever Arm ends to the Rocker to the Upper A-Arm, Lower A-Arm or the upright.

Attachment

This drop down list gives a list of suspension components that the Anti-Roll Bar can be attached to. For a Double A-Arm suspension a T-Bar type Anti-Roll Bar can be attached to the Upper A-Arm, Lower A-Arm, Rocker or Upright.


This point is where the Drop Link attaches to the Anti-Roll Bar.



Shaft – Chassis Pivot

This point is used to define the axis about which the Anti Roll bar will rotate during Pitch and Heave motions. The Chassis Pivot Point is located at the base of the Shaft

Shaft - Axis Point

The Axis Point is also used to define the axis about which the Anti Roll bar will rotate during Pitch and Heave motions. This axis is usually perpendicular to the vehicles longitudinal axis.

Shaft – Junction

The Junction point is where the Shaft intersects the Lever Arm.


Design/Inputs/Front Suspensions/Double A-Arm/Anti-Roll Bar/T-Bar Monoshock

A T-Bar type Anti-Roll Bar for a monoshock is comprised of a Lever Arm mounted perpendicular to the Anti-Roll Bar Shaft (also known as working length). A Chassis Pivot is mounted perpendicular to the base of the Shaft. The

Chassis Pivot is mounted to the chassis in a manner that allows the Anti-Roll Bar to rotate freely forward and

backward in the car. Two Drop Links are connected from the Lever Arm ends to the Rockers.




This point is used to define the axis about which the Anti Roll bar will rotate during Pitch and Heave motions. The

Chassis Pivot Point is located at the base of the Shaft

Shaft - Axis Point


Shaft – Junction



Design/Inputs/Front Suspensions/Double A-Arm/Anti-Roll Bar/T-Bar with 3rd Spring

A T-Bar with a third spring is comprised of a Lever Arm mounted perpendicular to the Anti-Roll Bar Shaft (also known as working length). A Chassis Pivot is mounted perpendicular to the base of the Shaft. The Chassis Pivot is

mounted to the chassis in a manner that allows the Anti-Roll Bar to rotate freely forward and backward in the car.

Two Drop Links are connected from the Lever Arm ends to the Rockers. A Coilover is then connected from the T-bar to the chassis. This Coilover is actuated in Heave and Pitch motions only.

Attachment


Arm suspension a T-Bar type Anti-Roll Bar can be attached to the Upper A-Arm, Lower A-Arm, Rocker or Upright.








Shaft - Axis Point


Shaft – Junction


Third Spring – Chassis

This point is where the Third Spring attaches to the Chassis.

Third Spring – T-Bar

This point is where the Third Spring attaches to the T-Bar.


Design/Inputs/Front Suspensions/Double A-Arm/Spring Actuation


Design/Inputs/Front Suspensions/Double A-Arm/Spring Actuation/Spring Actuation

Types

OptimumK currently has four Spring Actuation types for Double A-Arm suspensions. Each of these Spring Actuations has different packaging and functional requirements making them suitable to different types of vehicles.

To Insert a Spring;

1. Select the Suspension Design Item that you want to add the Spring to.


3. Scroll down to the Spring Type section.

4. Select the desired Spring Type from the drop down list.

• Direct Actuation

• Push/Pull Rod Configuration

• Separate Spring & Damper

• Monoshock Rotational

• Monoshock Sliding

• Torsion Bar

5. Enter Values


Design/Inputs/Front Suspensions/Double A-Arm/Spring Actuation/Direct Actuation

Direct Actuation is where the Coilovers are connected directly to the A-Arms or Upright.

Number of Coilovers

This drop down list selects the number of Coilovers that are to be used.

Attachment

This drop down list gives a list of suspension components that the Coilover can be attached to. For a Double A-Arm

suspension the Direct Acting Coilover can be attached to the Upper A-Arm, Lower A-Arm, or Upright.

Coilover - Chassis

This is the point where the Coilover connects to the Chassis.

Coilover - Attachment

This point is where the Coilover connects to the suspension component defined in the Attachment drop down list.


Design/Inputs/Front Suspensions/Double A-Arm/Spring Actuation/Push-Pull Actuation

Push/Pull Rod configuration is where the Coilovers are connected to the A-Arms via a Rocker. The Rockers are fixed to the Chassis and can only rotate about the Rocker Axis.


Rocker - Pivot

The axis that the Rocker rotates about is defined by the Rocker Pivot and Axis points. The Rocker Pivot point is

where the Rocker Axis is located on the Rocker.

Rocker - Axis

This is the other point that defines the axis which the Rocker rotates around.

Spring - Chassis


Spring - Rocker

This is the point where the Coilover connects to the Rocker.

Attachment

This drop down list gives a list of suspension components that the Push/Pull Rod can be attached to. For a Double A-

Arm suspension the Push/Pull Rod can be attached to the Upper A-Arm, Lower A-Arm or Upright.

Push/Pull Rod - Rocker

This is the point where the Push/Pull Rod connects to the Rocker

Push/Pull Rod - Attachment

This is the point where the Push/Pull Rod connects to the suspension component defined in the attachment drop down box.


Design/Inputs/Front Suspensions/Double A-Arm/Spring Actuation/Separate Spring &

Damper

Separate Spring and Damper Actuation is where the Spring and Damper are not assembled in the same unit. The Spring and Damper can have different attachment points, and can also be attached do different suspension

components.

Spring Attachment

This drop down list gives a list of suspension components that the Spring can be attached to. For a Double A-Arm

suspension the Spring can be attached to the Upper A-Arm, Lower A-Arm, or Upright.

Springs – Chassis

This is the point is where the Spring mounts to the Chassis.

Springs – Attachment

This is the point is where the Spring mounts to the suspension component that has been selected in the attachment drop down list.

Number of Dampers

This drop down list selects the number of dampers that are to be used.

Damper Attachment

This drop down list gives a list of suspension components that the Damper can be attached to. For a Double A-Arm

suspension the Damper can be attached to the Upper A-Arm, Lower A-Arm, or Upright.

Damper – Chassis

This is the point is where the Damper mounts to the Chassis.

Damper – Attachment

This is the point is where the Damper mounts to the suspension component that has been selected in the attachment drop down list.


Design/Inputs/Front Suspensions/Double A-Arm/Spring Actuation/Monoshock

Rotational Actuation

A Monoshock (Rotational) configuration is comprised of a single Coilover that is actuated from a T-Bar through a pair of Rockers. The T-Bar can rotate freely meaning the Coilover only compresses when both rockers are rotated at the

same time (i.e. during Heave and Pitch motions). The Rockers are fixed to the chassis and can only rotate about the Rocker Axis.


Attachment




This is the point where the Push/Pull Rod is connected to the Rocker.



Rocker - Pivot

The axis that the Rocker rotates about is defined by the Rocker Pivot and Axis points. The Rocker Pivot point is where the Rocker Axis is located on the Rocker.

Rocker - Axis


Drop Link - Rocker

This is the point where the Drop link connects to the Rocker.

Spring - Chassis


Spring – T-Bar

This is the point where the Coilover connects to the T-Bar.


Design/Inputs/Front Suspensions/Double A-Arm/Spring Actuation/Monoshock Sliding

Actuation

A Monoshock (Sliding) configuration is comprised of a single Coilover that is connected to a Mono Rocker that pivots around a Slide Bar. The Mono Rocker is also allowed to slide laterally on the Slide Bar which is connected to the

Chassis. A pair of Push/Pull Rods connect the Mono Rocker to either the Upper A-Arm, Lower A-Arm or Upright.


Attachment



Push/Pull Rod - Pivot

This is the point where the Push/Pull Rod connects to the Mono Rocker.


This is the point where the Push/Pull Rod connects to the suspension component defined in the attachment drop

down box.

Slide Bar - Pivot

This is the point where the Slide Bar attaches to the Chassis.

Spring - Chassis


Spring – Pivot

This is the point where the Coilover connects to the Mono Rocker.


Design/Inputs/Front Suspensions/Double A-Arm/Spring Actuation/Torsion Bar

[Page Name]

The Torsion Bar actuation type is very similar to the Push/Pull rod configuration but instead of springs it uses torsion bars that are mounted in the rockers. The Dampers are connected to the A-Arms via a Rocker. The Rockers are fixed

to the Chassis and can only rotate about the Rocker Axis.


Rocker - Pivot



Rocker - Axis


Damper - Chassis


Damper - Rocker


Attachment

This drop down list gives a list of suspension components that the Push/Pull Rod can be attached to. For a Double A-Arm suspension the Push/Pull Rod can be attached to the Upper A-Arm, Lower A-Arm or Upright.





down box.


Design/Inputs/Front Suspensions/Mac Pherson

Wishbone & Strut

Steering Wheel Geometry

Spring

Anti-Roll Bar


Design/Inputs/Front Suspensions/Mac Pherson/Points

The most common form of suspension type in production vehicles is the Mac Pherson Strut. The Mac Pherson

Suspension consists of a Strut connected from the Chassis to an Upright. A Wishbone connects the bottom of the

Upright to the Chassis.

To Edit the Mac Pherson Strut and Wishbone Geometry;

1. Select the Suspension Design Item that you want to edit.


3. Scroll to the Wishbone and Strut section.

4. Enter Values

Wishbone – Chassis Fore

This is the point where the leading point of the Wishbone connects to the Chassis.

Wishbone – Chassis Aft

This is the point where the trailing point of the Wishbone connects to the Chassis.

Wishbone – Upright

This is the point where the Wishbone connects to the Upright.

Strut – Upper Point

The Upper point is where the Strut connects to the Chassis

Strut – Lower Point

The Lower Point is where the Strut rigidly connects to the Upright


Design/Inputs/Front Suspensions/Mac Pherson/Steering


Design/Inputs/Front Suspensions/Mac Pherson/Steering/Steering Types

OptimumK currently has two steering types for Mac Pherson suspensions. Rack and Pinion is the most common type

of steering. Recirculating-Ball steering is used in some oval track racing series and classic production cars.



2. Click Summary to display the input summary window.



a. Rack and Pinion

b. Recirculating-ball Steering

5. Enter values


Design/Inputs/Front Suspensions/Mac Pherson/Steering/Rack & Pinion


Tie Rods – Rack







Design/Inputs/Front Suspensions/Mac Pherson/Steering/Recirculating-Ball

Recirculating Ball type steering is comprised of a Center Link that is rotated about a point on the Chassis when the steering wheel is turned. Two Tie Rods are connected form the Center Link to the Uprights.








Pitman Arm – Axis











Design/Inputs/Front Suspensions/Mac Pherson/Wheel Geometry







4. Enter values.

Half Track


Long. Offset





Vertical Offset

The Vertical Offset is the distance from the contact patch to the ground. A positive offset will place the contact patch above the ground while a negative offset will place the contact patch below the ground. Vertical Offset can be used

when the suspension coordinates are not referenced form the ground plane but another location.

Static Camber

Static camber is the angle between the wheel plane and the vertical, while the car is in a stationary position.

Negative camber is defined as the wheel plane being tilted towards the center of the vehicle. While positive camber is defined as the wheel plane being tilted away from the center of the vehicle.


Static Toe


when the front of the wheels are steered outwards while negative toe (toe in) is when the front of the wheels are steered inwards.


Rim Diameter

The Rim Diameter is the diameter of the rim edge not the tire bead seat. This is used as a reference point to measure toe distance.

Tire Diameter

The Tire Diameter is the outside diameter of the tire. The user can choose to use either the unloaded, loaded or rolling diameter of the tire

Tire Width


is not used in the calculation. The tire width is only used in the 3D display and to define the wheel axis in the output section


Design/Inputs/Front Suspensions/Mac Pherson/Spring

With a Mac Pherson type suspension the Damper and Spring are mounted together. However this does not mean that they are parallel to each other.

Edit a Spring;

1. Select the Suspension Design Item that you want to edit the Spring of.

2. Click Summary to display the Input Summary.

3. Scroll down to the Spring section.

4. Enter Values

Spring – Upper Center

This is the center of the Upper Spring seat.

Spring – Lower Center

This is center of the Lower Spring seat.


Design/Inputs/Front Suspensions/Mac Pherson/Anti-Roll Bar

The only available Anti-Roll Bar type for a Mac Pherson Suspension is a U-Bar. A U-Bar type Anti-Roll Bar is comprised of two Lever Arms mounted to the Anti-Roll Bar Shaft (also known as working length). The Shaft is

mounted to the chassis in a manner that allows the Anti Roll bar to rotate freely forward and backward in the car.

Two Drop Links are connected from the Lever Arm ends to the Wishbone.

Edit an Anti-Roll Bar;

1. Select the Suspension Design Item that you want to edit the Anti-Roll Bar of.


3. Scroll down to the Anti-Roll Bar section.

4. Enter Values.



Attachment

This drop down list gives a list of suspension components that the Anti-Roll Bar can be attached to. For a Mac

Pherson suspension the U-Bar type Anti-Roll Bar can be attached to the Wishbone or Upright.






Design/Inputs/Front Suspensions/Mac Pherson Pivot Arm

[Page Name]

Wishbone & Strut Steering

Wheel Geometry Spring

Anti-Roll Bar


Design/Inputs/Front Suspensions/Mac Pherson Pivot Arm/Points

[Page Name]

The Mac Pherson Strut Pivot Arm suspension type is found on the Renault Clio and Megane. The Suspension consists

of a Strut connected to the Chassis. This strut is then connected via two pivot points to an upright. A Wishbone

connects the bottom of the strut to the Chassis.

To Edit the Strut, Upright and Wishbone Geometry;



3. Scroll to the Wishbone, Upright and Strut section.

4. Enter Values






Wishbone – Strut

This is the point where the Wishbone connects to the Strut.




The Lower Point is where the Damper rigidly connects to the Strut

Upright – Upper Pivot

The Upper Pivot point is the upper point that connects the Upright to the Strut.

Upright – Lower Pivot

The Lower Pivot point is the lower point that connects the Upright to the Strut.

Strut Link – Wishbone

This point is where the Strut Link attaches to the Wishbone

Strut Link – Strut

This point is where the Strut Link attaches to the Strut


Design/Inputs/Front Suspensions/Mac Pherson Pivot Arm/Steering

[Page Name]


Design/Inputs/Front Suspensions/Mac Pherson Pivot Arm/Steering/Steering Types

[Page Name]

OptimumK currently has two steering types for Mac Pherson Pivot Arm suspensions. Rack and Pinion is the most

common type of steering. Recirculating-Ball steering is used in some oval track racing series and classic production

cars.






a. Rack and Pinion b. Recirculating-ball Steering

5. Enter values


Design/Inputs/Front Suspensions/Mac Pherson Pivot Arm/Steering/Rack & Pinion

[Page Name]


Tie Rods – Rack







Design/Inputs/Front Suspensions/Mac Pherson Pivot Arm/Steering/Recirulating-Ball

[Page Name]

Recirulating Ball type steering is comprised of a Center Link that is rotated about a point on the Chassis when the steering wheel is turned. Two Tie Rods are connected form the Center Link to the Uprights.








Pitman Arm – Axis











Design/Inputs/Front Suspensions/Mac Pherson Pivot Arm/Wheel Geometry

[Page Name]







8. Enter values.

Half Track


Long. Offset





Vertical Offset



Static Camber




Static Toe




Rim Diameter


Tire Diameter


Tire Width




Design/Inputs/Front Suspensions/Mac Pherson Pivot Arm/Spring

[Page Name]

With a Mac Pherson Pivot Arm type of suspension the Damper and Spring are mounted together. However this does not mean that they are parallel to each other.

Edit a Spring;




4. Enter Values

MCF_SpringPoints.jpg






Design/Inputs/Front Suspensions/Mac Pherson Pivot Arm/Anti-Roll Bar

[Page Name]

The only available Anti-Roll Bar type for a Mac Pherson Pivot Arm Suspension is a U-Bar. A U-Bar type Anti-Roll Bar is comprised of two Lever Arms mounted to the Anti-Roll Bar Shaft (also known as working length). The Shaft is


Two Drop Links are connected from the Lever Arm ends to either the Wishbone or Strut.





4. Enter Values.

MPF_ARBUBarPoints.jpg



Attachment


Pherson Pivot Arm suspension the U-Bar type Anti-Roll Bar can be attached to the Wishbone or Strut.






Design/Inputs/Front Suspensions/Nascar

Control Arms Steering

Wheel Geometry Spring & Shock

Sway Bar


Design/Inputs/Front Suspensions/Nascar/Control Arms

The Nascar dedicated front suspension uses Double A-Arms (Control Arms). A Double A-Arm suspension consists of

two “A” shaped Arms each of which has two points connected to the chassis and one point connected to the upright

(spindle).

Edit the Control Arm Geometry;

1. Select the Suspension Design Item that you want to edit the Control Arms of.


3. Scroll to the Control Arm section.

4. Enter Values


This is the point where the leading point of the Lower Control Arm connects to the Chassis.


This is the point where the trailing point of the Lower Control Arm connects to the Chassis.


Lower Arm – Spindle

This is the point where the Lower Control Arm connects to the Spindle.


This is the point where the leading point of the Upper Control Arm connects to the chassis..


This is the point where the trailing point of the Upper Control Arm connects to the Chassis.

Upper Arm – Spindle

This is the point where the Upper Control Arm connects to the Spindle.


Design/Inputs/Front Suspensions/Nascar/Steering

The Nascar dedicated front suspension uses the Recirculating Ball type steering. Recirculating Ball type steering is comprised of a Center Link that is rotated about a point on the chassis when the steering wheel is turned. Two Tie

Rods are connected form the Center Link to the Upright.




3. Scroll down to the Steering section.

4. Enter Values


Tie Rods – Spindle

This is the point where the Tie Rod connects to the Spindle.





Pitman Arm – Axis











Design/Inputs/Front Suspensions/Nascar/Wheel Geometry







4. Enter values.

Half Track


Long. Offset


longitudinal axis to the suspensions Origin. Long. Offset can be used when the suspension coordinates are not



Vertical Offset



Static Camber




Static Toe



steered inwards.


Rim Diameter



Tire Diameter



Tire Width



section


Design/Inputs/Front Suspensions/Nascar/Spring & Shock

The dedicated Nascar suspension allows the spring and shock to be mounted independently.

Edit a Spring or Shock;

1. Select the Suspension Design Item that you want to edit the Spring/Shock of.


3. Scroll down to the Spring/Shock section.

4. Enter Values

Springs – Chassis


Springs – Control Arm

This is the point is where the Spring mounts to the Lower Control Arm.

Shock – Chassis

This is the point is where the Shock mounts to the Chassis.

Shock – Control Arm

This is the point is where the Shock mounts to the Lower Control Arm.


Design/Inputs/Front Suspensions/Nascar/Sway Bar

The only available Anti-Roll Bar (Sway Bar) type for the Nascar dedicated suspension is a U-Bar. A U-Bar type Anti-Roll Bar is comprised of two Lever Arms mounted to the Anti-Roll Bar Shaft (also known as working length). The

Shaft is mounted to the chassis in a manner that allows the Anti Roll bar to rotate freely forward and backward in

the car. Two Drop Links are connected from the Lever Arm ends to the Lower Control Arm.

To Edit the Sway Bar;

1. Select the Suspension Design Item that you want to add the Sway Bar to.


3. Scroll down to the Sway Bar section.

4. Enter Values.



Drop Link – Sway Bar



This point is where the Drop Link attaches to the Lower Control Arm.


Design/Inputs/Rear Suspensions


Design/Inputs/Rear Suspensions/Double A-Arm

A-Arm Points

Tie Rod Wheel Geometry



Design/Inputs/Rear Suspensions/Double A-Arm/A-Arm Points

The most common form of suspension type is Double A-Arms. A Double A-Arm suspension consists of two “A”

shaped Arms each of which has two points connected to the chassis and one point connected to the upright.

To Edit the A-Arm Geometry;

1. Select the Suspension Design Item that you want to edit the A-Arms of.


3. Scroll to the A-Arm section.

4. Enter Values


This is the point where the leading point of the Lower A-Arm connects to the Chassis.


This is the point where the trailing point of the Lower A-Arm connects to the Chassis.

Lower Arm – Upright


This is the point where the Lower A-Arm connects to the Upright.


This is the point where the leading point of the Upper A-Arm connects to the chassis..


This is the point where the trailing point of the Upper A-Arm connects to the Chassis.

Upper Arm – Upright

This is the point where the Upper A-Arm connects to the Upright.


Design/Inputs/Rear Suspensions/Double A-Arm/Tie Rod

The Double A-Arm suspension uses Tie Rods on the rear to control the wheel toe.

Edit Tie Rods;

1. Select the Suspension Design Item that you want to edit the Tie Rods of.


3. Scroll to the Tie Rod section.

4. Enter Values

Attachment

This drop down list gives a list of suspension components that the Tie Rod can be attached to. For a Double A-Arm suspension the Tie Rod can be attached to the Chassis, Upper A-Arm or Lower A-Arm.

Tie Rods - Attachment

This point is where the Tie Rod attaches to the suspension component displayed in the attachment drop down list.

Tie Rods - Upright



Design/Inputs/Rear Suspensions/Double A-Arm/Wheel Geometry







4. Enter values.

Half Track


Long. Offset





Vertical Offset



Static Camber




Static Toe

Static toe is the angle between the wheel plane and the longitudinal axis of the vehicle. Positive toe (toe out) is when the front of the wheels are steered outwards while negative toe (toe in) is when the front of the wheels are

steered inwards.


Rim Diameter



Tire Diameter



Tire Width

The Tire Width is the overall width of the tire. OptimumK models the tire as an un-deformable disc so this dimension is not used in the calculation. The tire width is only used in the 3D display and to define the wheel axis in the output

section


Design/Inputs/Rear Suspensions/Double A-Arm/Anti-Roll Bar


Design/Inputs/Rear Suspensions/Double A-Arm/Anti-Roll Bar/Anti Roll Bar Types

OptimumK currently has four Anti Roll-Bar types for Double A-Arm suspensions. Each of these Anti-Roll Bars has







• U-Bar


• T-Bar


• T-Bar with Third Spring

5. Enter Values


Design/Inputs/Rear Suspensions/Double A-Arm/Anti-Roll Bar/U-Bar

A U-Bar type Anti-Roll Bar is comprised of two Lever arms mounted to the Anti-Roll Bar shaft (also known as working length). The shaft is mounted to the chassis in a manner that allows the Anti Roll bar to rotate freely forward and

backward in the car. Two drop links are connected from the lever arm ends to the rockers.


This is the point where the shaft is mounted to the chassis.





Attachment

This drop down list gives a list of suspension components that the Anti-Roll Bar can be attached to. for a Double A-Arm suspension the U-Bar type Anti-Roll Bar can be attached to the, Upper A-Arm, Lower A-Arm, Rocker or Upright.


Design/Inputs/Rear Suspensions/Double A-Arm/Anti-Roll Bar/U-Bar + Rocker



Intermediate Rockers. Another two Drop Links are then connected from the Rocker to the Upright or any of the suspension Links.








Rocker - Pivot

The axis that the rocker rotates about is defined by the Rocker Pivot and Axis points. The Rocker Pivot point is where

the Rocker Axis is located on the Rocker.



Attachment

This drop down list gives a list of suspension components that the Anti-Roll Bar can be attached to. For a Five Links suspension the U-Bar with Intermediate Rocker type Anti-Roll Bar can be attached to the Upright, Rocker or any of

the suspension Links.






Design/Inputs/Rear Suspensions/Double A-Arm/Anti-Roll Bar/T-Bar

A T-Bar type Anti-Roll Bar is comprised of a Lever Arm mounted perpendicular to the Anti-Roll Bar Shaft (also known as working length). A Chassis Pivot is mounted perpendicular to the base of the Shaft. The Chassis Pivot is mounted

to the chassis in a manner that allows the Anti-Roll Bar to rotate freely forward and backward in the car. Two Drop

Links are connected from the Lever Arm ends to the Upright, Rocker or any of the suspension Links.

Attachment

This drop down list gives a list of suspension components that the Anti-Roll Bar can be attached to. For a Five Links

suspension a T-Bar type Anti-Roll Bar can be attached to the Upright, Rocker or any of the suspension Links.








Shaft - Axis Point


Shaft – Junction



Design/Inputs/Rear Suspensions/Double A-Arm/Anti-Roll Bar/T-Bar Monoshock

A T-Bar type Anti-Roll Bar for a monoshock is comprised of a T Bar mounted perpendicular to the Anti-Roll Bar shaft (also known as working length). A chassis arm is mounted perpendicular to the base of the shaft. The chassis arm is


Two drop links are connected from the lever arm ends to the Rockers.

Drop Link – T Bar

This point is where the Drop Link attaches to the Anti-Roll Bar


This is the point where the shaft intersects the chassis lever arm.

Shaft - Axis Point

The Axis Point is used to define the axis about which the Anti Roll bar will rotate during Pitch and Heave motions. This axis is usually perpendicular to the vehicles longitudinal axis.

Shaft – Junction

The Junction point is where the shaft intersects the T Bar


Design/Inputs/Rear Suspensions/Double A-Arm/Anti-Roll Bar/T-Bar with 3rd Spring

A T-Bar with a third spring is comprised of a Lever Arm mounted perpendicular to the Anti-Roll Bar Shaft (also known as working length). A Chassis Pivot is mounted perpendicular to the base of the Shaft. The Chassis Pivot is

mounted to the chassis in a manner that allows the Anti-Roll Bar to rotate freely forward and backward in the car.

Two Drop Links are connected from the Lever Arm ends to the Rockers. A Coilover is then connected from the T-bar to the chassis. This Coilover is actuated in Heave and Pitch motions only.

Attachment


Arm suspension a T-Bar type Anti-Roll Bar can be attached to the Upper A-Arm, Lower A-Arm, Rocker or Upright.








Shaft - Axis Point


Shaft – Junction


Third Spring – Chassis

This point is where the Third Spring attaches to the Chassis.

Third Spring – T-Bar

This point is where the Third Spring attaches to the T-Bar.


Design/Inputs/Rear Suspensions/Double A-Arm/Spring Actuation


Design/Inputs/Rear Suspensions/Double A-Arm/Spring Actuation/Spring Actuation

Types

OptimumK currently has four Spring Actuation types for Double A-Arm suspensions. Each of these Spring Actuations

has different packaging and functional requirements making them suitable to different types of vehicles.

To Insert a Spring;










• Torsion Bar

5. Enter Values


Design/Inputs/Rear Suspensions/Double A-Arm/Spring Actuation/Direct Actuation

Push/Pull Rod configuration is where the Coilovers are connected to the A-Arms via a Rocker. The Rockers are fixed to the Chassis and can only rotate about the Rocker Axis.

Number of Coilovers


Attachment

This drop down list gives a list of suspension components that the Coilover can be attached to. For a Double A-Arm

suspension the Direct Acting Coilover can be attached to the Upper A-Arm, Lower A-Arm, or Upright.

Coilover - Chassis





Design/Inputs/Rear Suspensions/Double A-Arm/Spring Actuation/Push-Pull Actuation

Push/Pull Rod configuration is where the springs are connected to the A-Arms via a rocker. The rockers are fixed to the chassis and can only rotate about the rocker axis.


Rocker - Pivot

The axis that the rocker rotates about is defined by the Rocker Pivot and Axis points. The Rocker Pivot point is where the rocker axis is located on the rocker.

Rocker - Axis

This point defines the axis which the rocker rotates around.

Spring - Chassis

This is the point where the Coilover connects to the chassis.

Spring - Rocker



This is the point where the Push/Pull Rod is connected to the Rocker


This is the point where the Push/Pull Rod is connected to the Attachment defined in the attachment drop down box.

Attachment




Design/Inputs/Rear Suspensions/Double A-Arm/Spring Actuation/Separate Spring &

Damper


components.

Spring Attachment

This drop down list gives a list of suspension components that the Spring can be attached to. For a Double A-Arm suspension the Spring can be attached to the Upper A-Arm, Lower A-Arm, or Upright.

Springs – Chassis




This is the point is where the Spring mounts to the suspension component that has been selected in the attachment

drop down list.

Number of Dampers


Damper Attachment

This drop down list gives a list of suspension components that the Damper can be attached to. For a Double A-Arm suspension the Damper can be attached to the Upper A-Arm, Lower A-Arm, or Upright.

Damper – Chassis



This is the point is where the Damper mounts to the suspension component that has been selected in the

attachment drop down list.


Design/Inputs/Rear Suspensions/Double A-Arm/Spring Actuation/Monoshock

Rotational Actuation


same time (i.e. during Heave and Pitch motions). The Rockers are fixed to the chassis and can only rotate about the Rocker Axis.


Attachment







Rocker - Pivot


Rocker - Axis


Drop Link - Rocker


Spring - Chassis


Spring – T-Bar



Design/Inputs/Rear Suspensions/Double A-Arm/Spring Actuation/Monoshock Sliding

Actuation


Chassis. A pair of Push/Pull Rods connect the Mono Rocker to either the Upright or any of the suspension Links.


Attachment

This drop down list gives a list of suspension components that the Push/Pull Rod can be attached to. For a Five Links suspension the Push/Pull Rod can be attached to the Upright or any of the suspension Links.





down box.

Slide Bar - Pivot


Spring - Chassis


Spring – Pivot



Design/Inputs/Rear Suspensions/Double A-Arm/Spring Actuation/Torsion Bar

[Page Name]

The Torsion Bar actuation type is very similar to the Push/Pull rod configuration but instead of springs it uses torsion bars that are mounted in the rockers. The Dampers are connected to the A-Arms via a Rocker. The Rockers are fixed

to the Chassis and can only rotate about the Rocker Axis.


Rocker - Pivot


Rocker - Axis


Damper - Chassis


Damper - Rocker


Attachment








Design/Inputs/Rear Suspensions/Five Links

[Page Name]

Links Points Wheel Geometry



Design/Inputs/Rear Suspensions/Five Links/Link Points

[Page Name]

The Five Links suspension type consists of five individual links connected from the chassis to the upright. In some case two or more of these links can be attached to the same point.

To Edit the Five Link Geometry;

1. Select the Suspension Design Item that you want to edit the Links of.


3. Scroll to the Link section.

4. Enter Values

Link 1 – Chassis

This is the point where Link 1 connects to the Chassis.

Link 1 – Upright

This is the point where Link 1 connects to the Upright.

Link 2 – Chassis


Link 2 – Upright



Link 3 – Chassis


Link 3 – Upright


Link 4 – Chassis


Link 4 – Upright


Link 5 – Chassis


Link 5 – Upright



Design/Inputs/Rear Suspensions/Five Links/Wheel Geometry







4. Enter values.

Half Track


Longitudinal Offset

The Longitudinal Offset is the distance from a plane located perpendicular to the longitudinal axis to the suspensions origin. Longitudinal Offset can be used when the suspension coordinates are not measured form the origin but

another location.


Vertical Offset



Static Camber




Static Toe




Rim Diameter



Tire Diameter



Tire Width



section


Design/Inputs/Rear Suspensions/Five Links/Anti-Roll Bar

[Page Name]


Design/Inputs/Rear Suspensions/Five Links/Anti-Roll Bar/Anti Roll Bar Types

[Page Name]

OptimumK currently has four Anti Roll-Bar types for Five Link suspensions. Each of these Anti-Roll Bars has different packaging and functional requirements making them suitable to different types of vehicles.






• U-Bar


• T-Bar


5. Enter Values


Design/Inputs/Rear Suspensions/Five Links/Anti-Roll Bar/U-Bar

[Page Name]

A U-Bar type Anti-Roll Bar is comprised of two Lever Arms mounted to the Anti-Roll Bar Shaft (also known as working length). The shaft is mounted to the chassis in a manner that allows the Anti-Roll bar to rotate freely

forward and backward in the car. Two drop links are connected from the Lever Arm ends to the Upright, Rocker or

any of the suspension Links.



Attachment

This drop down list gives a list of suspension components that the Anti-Roll Bar can be attached to. For a Five Links suspension the U-Bar type Anti-Roll Bar can be attached to the Upright, Rocker or any of the suspension Links.






Design/Inputs/Rear Suspensions/Five Links/Anti-Roll Bar/U-Bar + Rocker

[Page Name]



Intermediate Rockers. Another two Drop Links are then connected from the Rocker to the Upright or any of the suspension Links.








Rocker - Pivot

The axis that the rocker rotates a about is defined by the Rocker Pivot and Axis points. The Rocker Pivot point is where the Rocker Axis is located on the Rocker.



Attachment

This drop down list gives a list of suspension components that the Anti-Roll Bar can be attached to. For a Five Links

suspension the U-Bar with Intermediate Rocker type Anti-Roll Bar can be attached to the Upright, Rocker or any of the suspension Links.






Design/Inputs/Rear Suspensions/Five Links/Anti-Roll Bar/T-Bar

[Page Name]








Shaft - Axis Point


Shaft – Junction



Design/Inputs/Rear Suspensions/Five Links/Anti-Roll Bar/T-Bar Monoshock

[Page Name]








Shaft - Axis Point


Shaft – Junction



Design/Inputs/Rear Suspensions/Five Links/Spring Actuation

[Page Name]


Design/Inputs/Rear Suspensions/Five Links/Spring Actuation/Spring Actuation Types

[Page Name]

OptimumK currently has five Spring Actuation types for Five Links suspensions. Each of these Spring Actuations has


To Insert a Spring;










5. Enter Values


Design/Inputs/Rear Suspensions/Five Links/Spring Actuation/Direct Actuation

[Page Name]

Direct Actuation is where the springs are connected directly to the Upright or Suspension Links.

Number of Coilovers


Coilover - Chassis

This is the point where the Coilover connects to the chassis.



Attachment

This drop down list gives a list of suspension components that the Coilover can be attached to. For a Five Links

suspension the Direct Acting Spring can be attached to the upright, or any of the suspension links.


Design/Inputs/Rear Suspensions/Five Links/Spring Actuation/Push-Pull Actuation

[Page Name]

Push/Pull Rod configuration is where the Coilovers are connected to the Links via a Rocker. The Rockers are fixed to the Chassis and can only rotate about the Rocker Axis.


Rocker - Pivot



Rocker - Axis


Spring - Chassis


Spring - Rocker


Attachment






down box.


Design/Inputs/Rear Suspensions/Five Links/Spring Actuation/Separate Spring &

Damper

[Page Name]


components.

Spring Attachment

This drop down list gives a list of suspension components that the Spring can be attached to. For a Five Links

suspension the Spring can be attached to the Upright or any of the suspension Links.

Springs – Chassis



This is the point is where the Spring mounts to the suspension component that has been selected in the attachment drop down list.


Number of Dampers


Damper Attachment

This drop down list gives a list of suspension components that the Damper can be attached to. For a Five Links suspension the Damper can be attached to the Upright or any of the suspension Links.

Damper – Chassis



This is the point is where the Damper mounts to the suspension component that has been selected in the

attachment drop down list.


Design/Inputs/Rear Suspensions/Five Links/Spring Actuation/Monoshock Rotational

Actuation

[Page Name]


same time (i.e. during Heave and Pitch motions). The Rockers are fixed to the chassis and can only rotate about the Rocker’s Axis.


Attachment






down box.

Rocker - Pivot



Rocker - Axis


Drop Link - Rocker


Spring - Chassis


Spring – T-Bar



Design/Inputs/Rear Suspensions/Five Links/Spring Actuation/Monoshock Sliding

Actuation

[Page Name]


Chassis. A pair of Push/Pull Rods connect the Mono Rocker to the Upright or any of the Suspension Links


Attachment

This drop down list gives a list of suspension components that the Push/Pull Rod can be attached to. For a Five Links

suspension the Push/Pull Rod can be attached to the Upright or any of the suspension Links.





Slide Bar - Pivot


Spring - Chassis


Spring – Pivot



Design/Inputs/Rear Suspensions/Mac Pherson

Wishbone & Strut

Tie Rod Wheel Geometry

Spring Anti-Roll Bar


Design/Inputs/Rear Suspensions/Mac Pherson/Wish & Strut

The most common form of suspension type in production vehicles is the Mac Pherson Strut. The Mac Pherson

Suspension consists of a Strut connected from the Chassis to an Upright. A Wishbone connects the bottom of the

Upright to the Chassis.

To Edit the Mac Pherson Strut and Wishbone Geometry;



3. Scroll to the Wishbone and Strut section.

4. Enter Values






Wishbone – Upright

This is the point where the Wishbone connects to the Upright.




The Lower Point is where the Strut rigidly connects to the Upright


Design/Inputs/Rear Suspensions/Mac Pherson/Tie Rod

The Mac Pherson suspension uses Tie Rods on the rear to control the wheel toe.

Edit Tie Rods;

1. Select the Suspension Design Item that you want to edit the Tie Rods of.


3. Scroll to the Tie Rod section.

4. Enter Values

Tie Rods - Chassis

This is the point where the Tie Rod connects to the Chassis.

Tie Rods - Upright



Design/Inputs/Rear Suspensions/Mac Pherson/Wheel Geometry







4. Enter values.

Half Track


Long. Offset





Vertical Offset



Static Camber




Static Toe




Rim Diameter


Tire Diameter


Tire Width




Design/Inputs/Rear Suspensions/Mac Pherson/Spring

With a Mac Pherson type suspension the Damper and Spring are mounted together. However this does not mean that they are parallel to each other.

Edit a Spring;


2. Click Summary to display the Input Summary.


4. Enter Values






Design/Inputs/Rear Suspensions/Mac Pherson/Anti-Roll Bar

The only available Anti-Roll Bar type for a Mac Pherson Suspension is a U-Bar. A U-Bar type Anti-Roll Bar is comprised of two Lever Arms mounted to the Anti-Roll Bar Shaft (also known as working length). The Shaft is


Two Drop Links are connected from the Lever Arm ends to the Wishbone.





4. Enter Values.




Attachment


Pherson suspension the U-Bar type Anti-Roll Bar can be attached to the Wishbone or Upright.






Design/Inputs/Rear Suspensions/V8 Supercar

Trailing Arms

Watts Linkage Wheel Geometry

CoilOver Anti-Roll Bar


Design/Inputs/Rear Suspensions/V8 Supercar/Trailing Arm Points

The V8 Supercar dedicated rear suspension uses a Live Axle with a Watts Linkage. This suspension consists of four

Trailing Arms each connected from the Axle to the Chassis.

Edit Trailing Arm geometry;

1. Select the Suspension Design Item that you want to edit the Trailing Arms of.


3. Scroll to the Trailing Arms section.

4. Enter Values

Upper Arm – Chassis

This is the point where the Upper Trailing Arm connects to the Chassis.


Upper Arm – Axle

This is the point where the Upper Trailing Arm connects to the Axle.

Lower Arm – Chassis

This is the point where the Lower Trailing Arm connects to the Chassis.

Lower Arm – Chassis

This is the point where the Lower Trailing Arm connects to the Axle.


Design/Inputs/Rear Suspensions/V8 Supercar/Watts Linkage

The V8 Supercar dedicated rear suspension uses a Live Axle with a Watts Linkage. The Watts Linkage consists of two Linkages mounted to an Axle at one and a Rocker at the other. The Rocker is free to rotate and move vertically but

not horizontally

Edit Watts Linkages;

1. Select the Suspension Design Item that you want to edit the Watts Linkage of.


3. Scroll to the Watts Links section.

4. Enter Values

Watts Links – Rocker

This is the point where the Link connects to the Rocker.

Watts Links – Axle

This is the point where the Link connects to the Axle.

Watts Links – Watts Pivot

This is the point that the rocker rotates about.

Watts Links – Watts Axis

This is the point along with the Watt Pivot point define the axis that the Rocker rotates about.


Design/Inputs/Rear Suspensions/V8 Supercar/Wheel Geometry







4. Enter values.

Half Track


Long. Offset





Vertical Offset



Static Camber




Static Toe



steered inwards.


Rim Diameter



Tire Diameter



Tire Width



section


Design/Inputs/Rear Suspensions/V8 Supercar/Spring

The V8 Supercar dedicated uses Coilover springs that are mounted to the Axle and Chassis.

Edit a Coilover;

1. Select the Suspension Design Item that you want to edit the Coilover of.


3. Scroll down to the Coilover section.

4. Enter Values

Coilover – Chassis

This is the point where the Coilover mounts to the Chassis.

Coilover – Axle

This is the point where the Coilover mounts to the Axle.


Design/Inputs/Rear Suspensions/V8 Supercar/Anti-Roll Bar

[Page Name]


Design/Inputs/Rear Suspensions/V8 Supercar/Anti-Roll Bar/Anti Roll Bar Types

[Page Name]

OptimumK currently has two Anti Roll-Bar types for the V8 Supercar suspension template. Each of these Anti-Roll Bars has different packaging and functional requirements.






• U-Bar


5. Enter Values


Design/Inputs/Rear Suspensions/V8 Supercar/Anti-Roll Bar/U-Bar

[Page Name]

A U-Bar type Anti-Roll Bar is comprised of two Lever arms mounted to the Anti-Roll Bar shaft (also known as working length). The shaft is mounted to the chassis or axle in a manner that allows the Anti Roll bar to rotate freely forward

and backward in the car. Two drop links are connected from the lever arm ends to the axle or chassis.

Pivot – Chassis/Axle Pivot

This is the point where the shaft is mounted to the Axle or Chassis. If the drop links are attached to the chassis then

the pivots are automatically attached to the axle. However If the drop links are attached to the axle then the pivots are automatically attached to the chassis.

Attachment

This drop down list box defines the suspension component that the drop links attach to. For a Watts Linkage suspension type the drop links can attach to the axle or chassis. If the Drop Links are attached to the Chassis then

the Shaft is attached to the Axle. If the Drop Links are attached the Axle then the Shaft is attached to the Chassis




This point is where the Drop Link attaches to the suspension component listed in the attachment drop down list.


Design/Inputs/Rear Suspensions/V8 Supercar/Anti-Roll Bar/U-Bar + Rocker

[Page Name]

A U-Bar with Intermediate Rocker type Anti-Roll Bar is comprised of two Lever Arms mounted to the Anti-Roll Bar Shaft (also known as working length). The Shaft is mounted to the chassis or axle in a manner that allows the Anti

Roll bar to rotate freely forward and backward in the car. Two Drop Links are connected from the Lever Arm ends to

a set of Intermediate Rockers. Another two Drop Links are then connected from the Rocker to the axle or chassis.


Pivot – Chassis/Axle Pivot

This is the point where the shaft is mounted to the Axle or Chassis. If the drop links are attached to the chassis then the pivots are automatically attached to the axle. However If the drop links are attached to the axle then the pivots

are automatically attached to the chassis.





Rocker - Pivot

The axis that the rocker rotates about is defined by the Rocker Pivot and Axis points. The Rocker Pivot point is where

the Rocker Axis is located on the Rocker.



Attachment

This drop down list box defines the suspension component that the drop links attach to. For a Watts Linkage suspension type the drop links can attach to the axle or chassis. If the Drop Links are attached to the Chassis then

the Shaft is attached to the Axle. If the Drop Links are attached the Axle then the Shaft is attached to the Chassis






Design/Inputs/Rear Suspensions/Nascar

Truck Arms

Track Bar

Wheel Geometry Spring & Shock


Design/Inputs/Rear Suspensions/Nascar/Truck Arms

The Nascar dedicated rear suspension uses a Live Axle with a Track Bar. This suspension consists of two Trucking

Arms that are connected from the chassis to the Axle.

Edit the Truck Arm Geometry;

1. Select the Suspension Design Item that you want to edit the Truck Arms of.


3. Scroll to the Arms section.

4. Enter Values

Arms – Chassis

This is the point is where the Truck Arm connects to the Chassis.

Arms – Axle

This is the point is where the Truck Arm connects to the Axle.


Design/Inputs/Rear Suspensions/Nascar/Track Bar

The Nascar dedicated rear suspension uses a Live Axle with a Track Bar. The Track Bar is a bar that is connected

from the Axle to the Chassis

Edit Track Bar;

1. Select the Suspension Design Item that you want to edit the Track Bar of.


3. Scroll to the Track Bar section.

4. Enter Values

Track Bar - Chassis

This is the point where the Track Bar connects to the Chassis.

Track Bar - Axle

This is the point where the Track Bar connects to the Axle.


Design/Inputs/Rear Suspensions/Nascar/Wheel Geometry







4. Enter values.

Half Track


Long. Offset





Vertical Offset



Static Camber




Static Toe



steered inwards.


Rim Diameter


Tire Diameter


Tire Width




Design/Inputs/Rear Suspensions/Nascar/Spring & Shock

The Spring and Shock on a Nascar suspension are mounted independently. The Spring is mounted to the Trucking Arms while the Shock is mounted to the Axle.

Edit a Spring or Shock;

1. Select the Suspension Design Item that you want to edit the Spring or Shock of.


3. Scroll down to the Spring and Shock section.

4. Enter Values


Springs – Chassis


Springs – Axle

This is the point is where the Spring mounts to the Trucking Arm.

Damper – Chassis

This is the point is where the Shock mounts to the Chassis.

Damper – Axle

This is the point is where the Shock mounts to the Axle.


Design/Inputs/Reference Points

The Reference Points are user definable points that can be on the chassis, upright, rocker or any of the suspension control arms. They can be used to see if a particular part of the car (e.g. exhaust, wing, etc.) will touch the ground

as the vehicle goes through its motion. They can also be used to locate the position of the center of gravity, center

of pressure or any other point that the user wishes to define. The name, color, location and attachment of the reference point cab be defined in the Reference Points section of the Input Window.

Insert a Reference Point;

1. Select the Suspension Design Item that you want to insert the Reference Point into.


3. Scroll down to the Reference Points section.

4. Enter the Reference Point’s Name.

5. Select a Color for the Reference Point by clicking the color box.

6. Enter the Reference Point’s X, Y and Z Coordinates.

7. Select the suspension component that the Reference Point will be attached to from the drop down list.


Design/Inputs/Design Comments

The design comments section is where users can enter comments about the Design Item. These comments will be exported with a Design Item and displayed in the comments window in the Analysis section when the Design Item is

used in a Simulation.

Insert a Design Comment;

1. Select the Suspension Design Item that you want to insert the comment into.


3. Scroll down to the Design Comments section.

4. Enter Comments


Design/Import-Export Design

Designs can be exported to an .xml file for use in other projects and Microsoft Excel. The .xml file format allows for easy input into a CAD system.

Import Design

To Import a Design:

1. Select Data > Import from the Input Toolbar.

2. Browse for and then select the saved Design Item file.

3. Click the Open button.

4. Select the components to import by checking the checkboxes.


Export Design

To Export a Design:

1. Select the Design Item from the Design Tree that is to be exported.

2. Select Data > Export from the Input Toolbar.

3. Enter the Name and Location where the file will be exported to.

4. Click the Save button.

The Design Item’s input coordinates and units will be exported to an .xml file in the specified location. If any of the other cells are moved or modified (other than the X Y Z values of the points), an error will occur when the file is

imported back into OptimumK.


Motion


Motion/Motion Overview

OptimumK is able to simulate four different vehicle motions.

• ROLL – Angular displacement about a user selected Roll Axis.

• PITCH – Angular displacement about a user selected Pitch Axis.

• HEAVE – Vertical displacement of the Chassis.

• STEERING – Angular displacement of the wheels around the Steering Axis.

Pitch, Roll and Steering are measured in degrees or radians while heave is measured in millimeters or inches

depending on the user preferred units.

These motions can be simulated individually or combined to give the designer a greater understanding of the

vehicle’s kinematics under all conditions. Motions can also be imported from a data logger or Microsoft Excel Spreadsheet.


Motion/Motion Section Layout

Motion Tree Window

The Motion Tree Window displays all the Motion Items that the user creates. These Motion Items can be stored in folders to assist with the organization of the motions.


Motion Tree Toolbar

New Folder – Creates a folder in the Motion Tree.

New Item – Creates a New Motion Item in the Motion Tree.

Delete – Deletes the selected Motion Item or folder.

Add to Simulator – Adds the selected Motion Item to the Simulator.

Motion Graph Window

The motion graph window displays the individual motion paths of the four modes of motion.


Motion Graph Toolbar

Add Point – Activates the cursor so it can Add Points to the Motion Graphs.

Delete Point – Activates the cursor so it can Remove Points from the Motion Graphs.

Import Motion – Import Motion from Microsoft Excel to OptimumK.

Export Motion – Export Motion from OptimumK to Microsoft Excel.

Import Logged Data – Create Motion from Laser Ride Height or Damper Position sensor data

Motion Points Window

The Motion Points window displays the Points that are in each motion graph. The user can modify the X and Y values of the points in the motion graphs by editing the values displayed in this window. A Motion Graph’s Points can be

displayed by clicking on the desired Motion Graph in the Motions Graphs Window. Points can be added and removed

from the list by right clicking on the list and selecting new or remove point.


Motion Comments Window

The motion comments window is where user’s can enter comments about the motion. The comments are exported with the motion and will re-appear in the Motion Comments Window when a motion is imported back into

OptimumK.

Import Logged Data Window

Open Logged Data File Button – Imports Data Logger file.

Select Data Button – Activates the cursor so it can select the data cells for each sensor.

Setup Button – Displays window where sensor setup information is entered.

Import into Motion Button – Imports Motion into OptimumK.


Motion/Motion Types


Motion/Motion Types /Roll

Roll Motion is when the vehicle’s chassis rotates around the Roll Axis. The Roll Axis is defined by the suspension

geometry and can move as the suspension articulates. Positive Roll is when the chassis rolls to the right (when

viewed from the behind of the car) while negative roll is when the chassis rolls to the left.

Instant Center

Instant Center (IC) is defined as the imaginary 2D pivot point of the suspension linkage, when viewed from the front

of the vehicle. In a double A-arm suspension setup for example, the IC is the point of intersection of the projected

upper and lower suspension arm. The term “instantaneous” means that the point is valid for a particular position of the suspension linkage, but is subject to displacement along with the movement of the suspension.

Roll Center

The 2D kinematic Roll Center (RC) is defined as the instantaneous center of rotation of the chassis about the ground. It is formed by the intersection of the lines connecting the contact patch of the tire to the IC of the opposite side.

Similar to ICs, the RC is also dynamic and varies its position based on the movement of the suspension linkages.


Roll Axis

The Roll Axis is the axis or line which connects the Roll Centers of the front and rear suspension. The Roll Axis is the

more appropriate method of determining the chassis roll characteristics of a 3D suspension model.

If both front and rear suspension geometries are selected for analysis, OptimumK performs all of the roll calculations

by pivoting the chassis on the roll axis. OptimumK calculates both front and rear roll centers simultaneously when performing the chassis motion calculations. This results in a more accurate representation of vehicle dynamics

characteristics.

The example below highlights the importance of using the roll axis to define the roll characteristics of the chassis:


The image on the left shows a vehicle which is at static ride height. The roll axis and pitch axis are defined by the blue and red line respectively. The front and rear roll center heights are equal and located on the centerline of the

car. Hence, the roll axis is parallel to both the vehicle longitudinal axis and the ground plane. For small values of pure chassis roll, the chassis will follow a cylindrical rotational motion about the roll axis.

However, when subject to multiple chassis motions comprising of bump, heave and roll, it is observed that the roll axis is skewed relatively large, as shown in the image on the left. In such a situation, the chassis will assume a

conical rotational motion about the roll axis. This kind of motion can only be deduced when the complete 3D suspension geometry is analyzed simultaneously.

The image below shows the skewed roll axis in plan view:


Motion/Motion Types /Pitch

Pitch Motion is when the vehicle’s chassis rotates around the Pitch Axis. The Pitch Axis is defined by the suspension

geometry and can move as the suspension articulates. Positive Pitch is when the chassis dives while negative Pitch is

when the chassis squats.

Pitch Center

The 2D kinematic Pitch Center is defined as the instantaneous center of rotation of the chassis about the ground,

when viewed from the side of the vehicle. Similar to Roll Center, it is also dynamic and varies its position based on

the movement of the suspension linkages.

The Pitch Center is formed by the intersection of the lines connecting the contact patch of the tire to the

Instantaneous Center (IC) of the opposite end, as shown in the image above.


Pitch Axis

The Pitch Axis is the more appropriate method of determining the chassis pitch characteristics of a 3D suspension

model. The Pitch Axis is the line that connects the left and right Pitch Centers. This is shown in the image below:

The pitch axis is defined by the red line in the analysis screen of OptimumK. If both front and rear suspension

geometries are selected for analysis. OptimumK calculates both left and right pitch centers simultaneously when

performing the chassis motion calculations.


Motion/Motion Types /Heave

Heave Motion is when the vehicle’s chassis moves vertically. Positive heave is when the chassis lifts. Negative heave

is when the chassis drops.

The Heave motion comprises of both the front and rear suspension linkages undergoing bump or droop simultaneously. This means that chassis does not undergo roll or pitch motions. Depending on the nature of the

suspension geometry, heave motion can induce track and wheelbase changes.


Image 1 shows the chassis at the neutral position, with the roll axis parallel to the vehicle longitudinal axis. With

Image 2, the chassis is subjected to 2.5° of pure roll, and the roll axis is observed to have shifted.

With Image 3 however, an initial heave motion of -10mm was included prior to the roll motion, and the roll axis is observed to have skewed further. This highlights the importance of including heave motions in the calculation.


Motion/Motion Types /Steering

Steering Motion is when the steering wheel is turned causing the front wheels to rotate around their kingpin axis. Positive steering is when the front wheels turn to the Left (when viewed from above the car) while negative steering

is when the front wheels turn to the right.

The steering motion provides the rotation of the front wheels about its kingpin axis taking into account the magnitude of parameters such as:

• Caster

• Steer Angle

• Camber

• Scrub Radius

The steering input will cause bump and droop motions on the front left and right wheels. As a result, the presence of steering motions will cause displacements of the roll and pitch axis, and thus affect the desired roll and pitch

motions.


The definitions of the steering parameters are shown in the images below:


Often, the effects of steering motion are neglected when simulating chassis roll in corners. This omission will cause a

less than accurate representation of the front roll center, and subsequently the roll axis and pitch axis.

Image 1 shows the chassis at the neutral position, with the roll axis parallel to the vehicle longitudinal axis. With

Image 2, the chassis is subjected to 2.5° of pure roll, and the roll axis is observed to have shifted slightly.

With Image 3 however, an initial steering input was carried out prior to the roll motion, and the roll axis is observed

to have skewed further. In real-world situations, chassis roll is often combined with steering angle, such as when the vehicle is in the middle of a corner. This highlights the importance of coupling steering motion along with other

suspension motions in a full 3D analysis to obtain an accurate representation of the suspension geometry behavior.


Motion/Create New Motion

Creating a New Motion Item

A Motion Item contains a Roll, Pitch, Heave and Steering motion. These motion types can be used individually or combined together.

To create a new Motion Item;

1. Select the New Item button from the Motion Tree Toolbar.

The newly created Motion Item will be displayed in the Motion Tree.

Renaming a Motion Item;

1. Right click on the Motion Item that is to be renamed.

2. Select Rename.

3. Enter new Motion Item name.


Motion Item Right-Click Options

The following options can be accessed by right-clicking on a Motion Item name.

New Folder – Adds a new folder to the Motion Tree.

New Item – Adds a new Motion Item to the Motion Tree.

Delete – Deletes the currently selected Motion Item.

Rename – Highlights the Motion Item or folder name so that it can be renamed.

Cut – Deletes and copies the Motion Item to the clipboard.

Copy – Copies the Motion Item to the clipboard.

Paste – Pastes the Motion Item that is currently in the clipboard.

Add to Simulator – Adds the selected Motion Item to the Simulator.


Motion/Motion Graphs

The four Motion Graphs are displayed on the right hand side of the screen. In each graph the X value is the

percentage of the total time duration of the motion. The Y value is the direction and magnitude of the motion.

Editing Motion Graphs

To add a new Data Point;

1. Activate the Add Data Point button in the Motion Graph Toolbar.

2. Add data points by clicking anywhere in the Motion Graphs.


Alternatively Data Points can be added by;

1. Clicking on a Motion Graph to display the Motion Points Table.

2. Right Clicking on a point listed in the table and selecting New Point.

3. Enter point coordinates into to the Add Data Point Window.

4. Click the Add button.

To Edit existing Data Points:

1. Click on a Motion Graph to display the Motion Points Table.

2. Click on the X or Y value of a Data Point.

3. Enter new value.

To remove a Data Point

1. Activate the Remove Data Point button in the Motion Graph Toolbar.

2. Select the Data Point in the Motion Graph that is to be removed.


Alternatively Data Points can be removed by;

1. Clicking on a Motion Graph to display the Motion Points Table.

2. Right Clicking on a point listed in the table and selecting Delete Point.

Motion Sign Convention


Positive Pitch – Anti-Clockwise rotation about the Pitch Axis. (When viewed from left of vehicle)

Positive Heave – Vertically up.

Positive Steering – Wheels turn to the Left. (When viewed from above vehicle)


Motion/Import-Export Motion

Export Motion

Motions are exported to an .xml file for use in other OptimumK projects or Microsoft Excel.

To Export a Motion:

1. Select the Motion Item from the Motion Tree, which is to be exported.

2. Click the Export Motion button in the Motion Graph Toolbar.



The Motion Item will then be exported to the selected location as a .xml file. This file can be opened and edited

using Microsoft Excel.

Import Motion

Previously exported motions can be imported into other OptimumK projects.

To import a Motion:

1. Click the Import Motion button in the Motion Graph Toolbar.

2. Browse for and then select the saved motion file.

3. Click the Open button.

The motion will then be imported into the current OptimumK project.


Import Motion (Data Logger)

A motion can be created from an exported .csv or .xml file of any data logger. The motion can be created using

either 4 damper position sensors or 3 ride height sensors.

To import a Motion from a Data Logger:

1. Export the 4 damper position or 3 ride height Sensor’s Data to a .csv or .xml file from the Data Logger.

2. Click the Import Logged Data button in the Motion Graph Toolbar to open the Import Logged Data

Window.

3. Click the Open Logged Data File button.

4. Browse for the exported Data Logger file and click Open to display the Data Logger file in the Import Logged

Data Window.

5. Select the type of sensors that will be used to generate the motion (i.e. Ride Height or Damper Position)

Ride Height Sensors

6. Select whether there are Two Front of Two Rear ride height sensors from the drop down list.

7. Select the Ride Height Sensor Data by clicking the Select Data button next to a Ride Height sensor.

8. Then Select the Cells containing the data of the Ride Height sensor.

9. Repeat Steps 7-8 for the other two Ride Height sensors and the Steering Wheel Angle sensor.

10. Define the location of the Ride Height sensors by clicking the Sensor Setup button and entering the Ride

Height sensor locations.

11. Click the Generate Motion button to generate the OptimumK motion.

Damper Position Sensors

6. Select the Damper Position Sensor Data by clicking the Select Data button next to a Damper Position

sensor.

7. Then Select the Cells containing the data of the Damper Position sensor

8. Repeat Steps 6-7 for the other three Damper Position sensors and the Steering Wheel Angle sensor.

9. Click the Sensor Setup button and enter the Damper Position sensor Motion ratios and vehicle dimensions.

10. Click the Generate Motion button to generate the OptimumK motion.

The motion will then be imported into the current OptimumK project. When importing a motion from a data logger the number of motion steps should match the total number of samples over the entire motion. For example if a set

of linear potentiometers are logged at a frequency of 100Hz over a 50 second lap then the number of motion steps will need to equal 100x50 = 5000 to ensure that all the logged data is included in the motion. After the motion has

been generated OptimumK will automatically change the number of steps to match the logging frequency.


Simulator


Simulator/Simulator Overview

To view the results of a suspension design when placed under a given motion you first need to run a simulation

containing the suspension design and motion path. This is done by adding a Design Item(s) and Motion Item to the

Simulator and then running a Simulation so the results can be calculated.


Simulator/Simulator Toolbar

Run Simulation – Starts the Simulation Calculation Process after which the results can be Analyzed.

Simulation Batch Run – Opens the Simulation Batch Run Window.

Selected Front Suspension – Front suspension Design Item that is Currently in the Simulator.

Selected Rear Suspension – Rear suspension Design item that is Currently in the Simulator.

Selected Motion – Motion Item that is Currently in the Simulator.

Remove Selected Item – Removes the corresponding selected Design or Motion item from the Simulator.


Simulator/Add Design

To add a Design Item to the Simulator;

1. Select the Front Suspension Design Item from the Design Tree.

2. Click the Add to Simulator button in the Design Tree Toolbar.

3. Select the Rear Suspension Design Item from the Design Tree.

4. Click the Add to Simulator button in the Design Tree Toolbar.

A simulation can run with only one suspension half or both the front and rear.

Once added the front suspension item name will be displayed in the Selected Front Suspension segment of the

Simulator Toolbar. The added rear suspension item name will be displayed in the Selected Rear Suspension segment of the Simulator Toolbar.

Design Items that are currently in the simulator will be displayed red in the Design Tree.

Once an item is added to the Simulator it does not need to be re-added if a change is made to that particular item. An exception to this is if the name of the item is changed, the item will then need to be re-added to the Simulator.


Simulator/Add Motion

To add a Motion Item to the Simulator;

1. Select the Motion Item from the Motion Tree.

2. Click the Add to Simulator button in the Motion Tree Toolbar.

Once added the Motion Item name will be displayed in the Selected Motion Segment of the Simulator Toolbar.

Motion Items that are currently in the Simulator are displayed red in the Motion Tree.

Once an item is added to the Simulator it does not need to be re-added if a change is made to that particular item. An exception to this is if the name of the item is changed, the item will then need to be re-added to the Simulator.


Simulator/Preferences

The Simulator Preferences can be accessed by selecting options in the tool strip menu or by clicking the OptimumK Preferences button in the Program Toolbar.

Motion Steps

The number of motion steps is the number of intervals that the motion is split up into during the calculation process.

The larger the number of motion steps, the longer the analysis calculation time. The default setting (50 steps) is a good compromise for all motions other than Imported Track Data.

When importing a motion from a data logger the number of motion steps should match the total number of samples over the entire motion. For example if a set of linear potentiometers are logged at a frequency of 100Hz over a 50

second lap then the number of motion steps will need to equal 100x50 = 5000 to ensure that all the logged data is included in the motion.


Roll and Pitch Axis

The user can select from three different Roll and Pitch axes that will be used in the calculation.

Moving Axis

When Moving Axis is selected Roll and Pitch motions are applied around the moving kinematics Roll and Pitch Axes

which were calculated in the previous motion step.

Fixed Axis With a fixed axis, the position of the Roll and Pitch axis remains constant regardless of the kinematical movement of

the suspension. The suspension rolls around an axis defined by two points that are located on the ground, in the

middle of the front and rear contact patches respectively. Similarly the suspension pitches around an axis defined by two points located on the ground, in the middle of the left and right wheelbases.

User Defined Axis

The user defined axis allows the user to input a predetermined Roll and Pitch axes. This can be done by entering the Front and Rear points of the Roll Axis and the Left and Right points of the pitch axis

Run Options

3D Visualization

The 3D visualization option toggles the animation window during the simulation. Selecting “On” allows the user to visualize the suspension kinematics real-time as the calculation progresses. However, this increases the load on the

CPU and requires more processing time. Users with a slower processor or graphic card would benefit by switching the 3D Visualization to “Off”.

Autosave Before Run When activated the project will save automatically each time a simulation is run.

Enter Simulation Name Before Simulation is Run

When activated a window appears before a simulations is run where the name of the simulation can be entered.


Simulator/Run Simulation

To Run a Simulation;

1. Add a Design and Motion to the Simulator.

2. Press the Run Simulation button in the Simulator Toolbar.

3. Enter the Name of the simulation in the Simulation Name window.

Once the Simulator is finished the simulation results can be viewed and analyzed in the Analysis Section of OptimumK.

Simulator Runtime Window

While the Simulator is processing a 3D animation of the suspension undergoing the selected motion is displayed on the screen. The display can be Rotated, Zoomed and Translated by using the tools in the View Orientation Toolbar.

The Simulator Window also displays the progress of the simulation with a Slider in the Motion Path Diagram and a display of time remaining.


Simulator/Batch Run

[Page Name]

The batch run feature allows users to run multiple simulations in a row with different suspension pickup point locations of one or more points.

To Run a Batch of Simulations;

1. Add a Design and Motion to the Simulator.

2. Press the Batch Run Simulation button in the Simulator Toolbar.

3. Add the Suspension Points that are to be modified for each run from the Input Tree.

4. Add the Simulation Runs by clicking the Add Run Button.

5. Enter the Suspension Point Values for each Run.

6. Click Run to run the simulations

7. Enter the Name of the simulation in the Simulation Name window.

Once the Simulator is finished the simulation results of all the runs can be viewed and analyzed in the Analysis Section of OptimumK.


Add Run – Adds a new simulation run.

Add Multiple Runs – Adds multiple simulation runs.

Delete Run – Deletes selected simulation run.

Linearise Input – Evenly spaces the Point Values of a selected Input Point.

Suspension Points – Points that can be modified in the batch run.

Run Button – Runs all the simulation runs simultaneously.

Close Window – Closes the Batch Run Window.


Analysis


Analysis/Analysis Overview

OptimumK is able to calculate over 400 different variables from a single suspension simulation. The Analysis section

of OptimumK is where this data can be viewed and compared using three different methods.

Graph

The Graph Tool is able to plot two data channels against each other. These plots can also be overlayed and

compared to other simulated data which has previously been simulated. This allows for easy comparison between a

number of different suspension design iterations.

Report

The Report Tool tabulates the value(s) of the selected data channel(s). It can also display the Minimum, Maximum,

Average, Variance, Absolute Maximum, Range, Start, End and Standard Deviation of the simulated data channel. Data can also be compared against other simulations which have been simulated previously.

Animation

The Animation Tool displays a moving 3D animation of the suspension as it undergoes a given motion. The animation can be rotated, zoomed and translated to give the designer a better understanding of how the suspension

is behaving.

Output Data

The Output Data Tool tabulates all the values of the user selected data channels that are outputted during a

simulation run. Only the data of the master simulation can be displayed in an Output Data Tool.


Analysis/Analysis Section Layout

Analysis Tree Window

The Analysis Tree Window displays all the Analysis Items that the user creates. These Analysis Items can be stored

in folders to assist with organization of the analysis.


Analysis Tree Toolbar

New Folder – Creates a new folder in the Analysis Tree.

New Item – Creates a new Analysis Items in the Analysis Tree.

Delete – Deletes the selected Analysis Item or folder.

Data Selection – Displays the Simulation Data Selection Window.

Analysis Workspace

The Analysis Workspace is where the Graph, Report, Animation and Output Data Tools are displayed.


Analysis Workspace Toolbar

Graph Tool – Used to plot Graphs in the workspace.

Report Tool – Used to compile Channel Reports in the workspace.

Animation Tool – Used to display an Animation of the suspension in the workspace.

Output Data Tool – Used to display Simulation Output Data in the workspace.

Forward – Steps animation forward.

Play – Plays an animation of the suspension undergoing the motion.

Stop – Stops the animation of the suspension undergoing the motion.

Backward – Steps animation backward.

Slider – Current location of the animation in Motion Path Diagram.

Motion Path Diagram – Displays motion paths of Master Simulation.

Simulation Data Selection Window

From this window the user can select which simulations to display in the graph, report and animation tools.


Simulation Properties Window

The Front Suspension, Rear Suspension, Motion and Simulation Properties are displayed in the Simulation Properties Window when the properties buttons are toggled.

Simulation Properties Toolbar

Details – Displays the Suspension’s input coordinates and motion that were used in the Simulation.

Export – Exports the Simulation data channels to a csv file for use in Microsoft Excel.

Master – Sets the currently selected Simulation as the Master Simulation

Simulation Properties – Displays the Simulation run time and date, Reference Distance and the Simulation

Comments.

Front Suspension Properties – Displays the Front Suspensions Design Item Name and Comments.

Rear Suspension Properties – Displays the Rear Suspension Design Item Name and Comments.

Motion Properties – Displays the Motion Item Name and Comments.


Graph Properties Window

All the Graph Properties can be edited from the graph properties window.


Report Properties Window

All the Report Properties can be edited from the report properties window.

Output Data Properties Window

All the Output Data Properties can be edited from the output data properties window.


Analysis/Create New Analysis

Analysis Item

An Analysis Item is where multiple Graphs, Reports ,Animations and Output Data tools can be viewed

simultaneously.

To Create a new Analysis Item;

1. Select the New Item button from the Analysis Tree Toolbar.

To Rename an Analysis Item;

1. Right click on the Analysis Item that is to be removed.

2. Select Rename.

3. Type in Analysis Item name new name.

Analysis Item Right-Click Options

The following options can be accessed by right-clicking on a Analysis Item name.

New Folder – Adds a new folder to the Analysis Tree.

New Item – Adds a new Analysis Item to the Analysis Tree.

Delete – Deletes the currently selected Analysis Item.

Rename – Highlights the Analysis Item or folder name so that it can be renamed.

Cut – Deletes and copies the Analysis Item to the clipboard.

Copy – Copies the Analysis Item to the clipboard.

Paste – Pastes the Analysis Item that is currently in the clipboard.


Analysis Tools

OptimumK has four Analysis Tools (Graph, Report, Animation and Output Data) to assist the user analyze the

simulation data. Collections of theses Analysis Tools can be stored in an Analysis Item.

To Insert an analysis tool;

1. Select the Analysis Item that the Analysis Tool will be stored in.

2. Click and hold one of the Analysis Tool buttons in the Analysis Workspace Toolbar.

3. Drag the Analysis Tool into the Analysis Workspace (a grid will appear to aid placement of the tool).

4. Drop the Analysis Tool onto the Analysis Workspace.

Moving and Resizing a Tool

To Move an Analysis Tool:

1. Place the mouse cursor on the Border of the Analysis Tool. The mouse cursor will change to cross arrow.

2. Click and Drag the Analysis Tool to the desired location

To Resize an Analysis Tool;

1. Place the mouse cursor on the Corner of an Analysis Tool’s Border. The mouse cursor will change to a resizable arrow.

2. Click and Drag the border of the Analysis Tool to the desired display size.


Analysis/Analysis Tools

OptimumK has four Analysis Tools (Graph, Report, Animation and Output Data) to assist the user analyze the

simulation data. Collections of theses Analysis Tools can be stored in an Analysis Item.

To Insert an analysis tool;

1. Select the Analysis Item that the Analysis Tool will be stored in.

2. Click and hold one of the Analysis Tool buttons in the Analysis Workspace Toolbar.

3. Drag the Analysis Tool into the Analysis Workspace (a grid will appear to aid placement of the tool).

4. Drop the Analysis Tool onto the Analysis Workspace.


Analysis/Analysis Tools/Graph Tool

When a Graph is selected the Graph Properties Window automatically appears on the left hand side of the screen.

Each Graph consists of a user-definable X and Y axis. A maximum of two data channels can be plotted on the Y-axis

of each Graph.


Graph Labels

Chart Title – User defined Chart Title which is displayed at the top of the Graph.

X Axis Title - User defined name given to the x-axis. The default channel title is automatically inserted when the X-

axis channel is selected from the channel list.

Channel 1 Title – User defined name given to the primary data channel. The default channel title is automatically

inserted when the X-axis channel is selected from the channel list.

Channel 2 Title - User defined name given to the secondary data channel. The default channel title is automatically inserted when the X-axis channel is selected from the channel list.

Graph Data

X Data - By selecting the X button the user can select from a list of Data Channels that can be assigned to the x-axis of the Graph.

X Axis Scale - The Min and Max Values define the minimum and maximum range of the x-axis.

Channel 1 Data - By selecting the Channel 1 button the user can select from a list of Data Channels that can be assigned to the y-axis of the Graph.


Channel 2 Data - By selecting the Channel 2 button the user can select a second data channel from a list of Data Channels that can be assigned to the y-axis of the graph.

Y Axis Scale - The Min and Max Values define the minimum and maximum range of the y-axis.

Graph Display Options

“0” Cross Display Option - This option automatically adjust the Graph so that the x and y axis cross at the origin

(0,0).

Axis Equal Display Option - This option automatically adjusts the Graph so that the x and y axis have the same

scale.

Auto Scale Display Option - This option automatically adjusts the Graphs axis scale so that the plotted lines fit

within the plot area.

Graph Zoom In – The user can zoom in on a particular area of a Graph by clicking and dragging a box around the desired area. This can be repeated more than once until the desired level of magnification is achieved.

Graph Zoom Out - To un-zoom, right click and select un-zoom from the right-click options menu. This may have to

be repeated several times to return to the original scale, depending on the initial level of magnification.

Right-Click Options

The following options can be accessed by right-clicking on a Graph.


Copy – Copies the Graph to the clipboard.

Save Image As – Saves the Graph as an image to a user defined location.

Page Setup – Displays page setup options that are used when printing.

Print – Prints Graph to user selected printer.

Un-Zoom – Un-Zooms the Graph scale.

Set Scale to Default – Resizes Graph scale so the entire Graph is displayed in the screen.

Delete – Deletes the Graph.


Analysis/Analysis Tools /Report Tool

When a Report is selected the Report Properties Window automatically appears on the left hand side of the screen.

Each Report consists a table where data channels can be displayed simultaneously.


Title

Channel Report Title – This title will appear at the top of the Report.

Data

Add Data - By selecting the Add button the user can select from a list of Data Channels that can be displayed in

the Report.

Remove Data - To remove a data channel from a Report, select the channel from the channel list and click the

Remove button.


Display Options

When selected the following values are displayed in the Report:

Minimum – Minimum value of the data channel that occurs during the Simulation.

Maximum – Maximum value of the data channel that occurs during the Simulation.

Average – Average value of the data channel over the Simulation.

Variance – Variance of the channel data values over the Simulation.

Abs Max –Absolute maximum value of the channel data over the Simulation.

Range - Difference between the maximum and minimum data channel values that occurs during a Simulation.

Start – Initial data channel value at the beginning of the Simulation.

End – Final data channel value at the end of the Simulation.

Std Dev – Standard Deviation of the data channel over the Simulation.

Right-Click Options

The following options can be accessed by right-clicking on a Report.

Delete – Deletes the Report.


Analysis/Analysis Tools /Animation Tool

The Animation Tool displays a 3D animation of the suspension as it undergoes the given motion. The Animation view can be orientated, using the tools in the View Orientation Toolbar. The Roll Axis (Blue) and Pitch Axis (Red) are also

displayed in the Animation.


Translate View - Scrolls the 3D graphical representation across the Animation Toll display.

Rotate View - Rotates the 3D graphical representation view about a point.

Zoom - Dynamically changes the scale of the 3D graphical representation.

Zoom to Selected Area - Zooms into an area that is selected by dragging a bounding box.

Transparent View - Changes the opacity of the tires.

Parrallel/Perspective –Toggles the 3D graphical representation between parallel and perspective image distortion.

Standard Views – Rotates the 3D graphical representation to front, back, right, left, top or bottom view.

Background Color – Changes the background gradient to a user selected color.

Animate Animation

To Play an Animation:

1. Click the Play Animation button in the Analysis Workspace Toolbar.

To Stop an Animation:

2. Click the Stop Animation button in the Analysis Workspace Toolbar.

The Motion Path Diagram shows the motion paths that are selected in the Analysis Workspace Toolbar. The Slider indicates the immediate position of Animation with regards to the Motion Path. The slider can be positioned manually

across the timescale using the mouse, by clicking and draging the slider to the desired position.


Display Options

Extra lines and Axes can be displayed in an Animation Tool by checking the check boxes in the display section of the

OptimumK Preferences window. The OptimumK Preferences can be accessed by clicking the OptimumK Preferences button in the Program Toolbar.

Display Roll Axis – Displays the axis that the car rolls around during Roll Motions.

Display Pitch Axis – Displays the axis that the car pitches around during Pitch Motions.

Display Kinematics Axis When Using Fixed Roll and Pitch Axis – Displays the suspensions kinematics axis

when the Roll and Pitch axis are set to fixed or user defined in the Simulator Preferences.

Display Origin in Animation – Displays the origin along with the direction of the X,Y and Z axes defined in the

Simulator Output Preferences.

Instant Axis – Displays the Instant Axis of the associated suspension corner.

Front View IC to CP – Draws a line from the Front View Instant Center point to the associated tire’s Contact Patch.

Side View IC to CP – Draws a line from the Side View Instant Center point to the associated tire’s Contact Patch.

Tire Same Color as Instant Axis – Changes the color of the tire to match the Instant Axis.


Analysis/Analysis Tools/Output Data Tool

[Page Name]

When an Output Data tool is selected the Output Data Properties Window automatically appears on the left hand

side of the screen. Each Output Data tool consists of a table where the data channels from a simulation can be

displayed simultaneously.


Data Channels

Add Data - By selecting the Add button. The user can select from a list of Data Channels that can be displayed in

the Output Data tool.

Remove Data - To remove a data channel from an Output Data tool, select the channel from the channel list and

click the Remove button.

Right-Click Options

The following options can be accessed by right-clicking on a Data Channel Name in the Output Data tool.

Remove – Removes the Data Channel from the Output Data tool.


Analysis/Overlay Simulation Data

A powerful feature of OptimumK is the ability to overlay data from a large number of design iterations. For example

if you wanted to investigate how the toe angle of your front wheels varies during bump (i.e. Bump Steer) when the

steering rack is located at different heights. You can run a number of simulations with the steering rack positioned in different locations and then overlay the results in a Graph or Channel Report.

Display Simulation Data in Graph/Report

All the simulations that have been simulated in a project are listed in the Simulation Data Selection Window.

To display Simulation Data;

1. Click the Data Selection button in the Analysis Tree Toolbar to display the Simulation Data Selection

Window

2. Check the box next to the simulation that is to be displayed.

3. Click the Update Analysis Tools button to refresh the Analysis Tools.

The selected simulations will appear in all the Graphs and Reports that have been created in the Analysis Section. The default simulation name is the date and time that the simulation was run. If a new simulation is run the data

from the new simulation will be displayed automatically in the Graphs and Reports.


Master Simulation

The Master Simulation is the simulation that is displayed in the 3D animation.

To change a simulation to the master simulation

1. Make sure the Simulation is Checked.

2. Select the Simulation name from the Simulation Data Selection Window.

3. Click the Master button in the Simulation Properties Toolbar.

4. Click the Update Analysis Tools button to refresh the Analysis Tools.

The selected simulation will now become the Master Simulation. The letter M will appear to the right of the

simulation name.

Right-Click Options

The following options can be accessed by right-clicking on a Simulation name.

Change Color – Changes the color of the selected Simulations Graph lines and Report text.

Master – Sets the selected Simulation to the Master Simulation.

Export to Csv – Exports the Simulation data channels to a Csv file for use in Microsoft Excel.

Rename Simulation – Changes the Simulation name.

Delete Simulation – Deletes the selected Simulation.


Analysis/Export Analysis

Export Simulation Data

The simulation data can be exported to a *.csv file for use in Microsoft Excel.

To Export simulation data;

1. Right-click on the simulation name in the Simulation Data Selection Window.

2. Select Export to Csv.

3. Select the Data Channels that will be exported by checking the box next to the data channel.

4. Click the Ok button.



The Simulation data will then be exported to the user defined location as a Csv file. This file can then be opened

using Microsoft Excel.

Microsoft Excel (only versions early than 2006) cannot display more than 256 columns of data so once the number of

selected data channels is greater than 256 the number of selected channels text will turn red. All channels greater than 256 will be exported but will not be displayed in Microsoft Excel (only versions early than 2006).


Export Graph

To Export a Graph;

1. Right-click on the Graph that is to be exported.

2. Select Save Image As.

3. Enter the Name and Location where graph image will be exported to.

4. Click the Save button

Graph images can be saved as PNG, Gif, Jpeg, Tiff or Bmp format.

Export Report

This feature will be made available in a future updated version of OptimumK


Output Channels/Motion

Roll

The Roll output channel is the inputted Roll motion measured in degrees (or radians). This output is useful to plot on

the x-axis of an Analysis Graph when other outputs need to be compared against Roll angle.

More about Roll Motion…

Pitch

The Pitch output channel is the inputted Pitch motion measured in degrees (or radians). This output is useful to plot on the x-axis of an Analysis Graph when other outputs need to be compared against Pitch angle.

More about Pitch Motion…

Heave

The Heave output channel is the inputted Heave motion measured in millimeters (or inches). This output is useful to plot on the x-axis of an Analysis Graph when other outputs need to be compared against Heave.

More about Heave Motion…

Steer

The Steer output channel is the inputted Steer motion measured in degrees (or radians). This output is useful to plot

on the x-axis of an Analysis Graph when other outputs need to be compared against Steering angle.

More about Steering Motion…

%Completion

This is the percentage of the total time duration of the Motion. This output is useful to plot on the x-axis of an

Analysis Graph when other outputs need to be compared against a combination of Motions.

A full list of output channels can be found here.


Output Channels/Points

The point outputs are the instantaneous X, Y and Z coordinates of all the suspension points that were Inputted to design the suspension. These coordinates use the output reference system defined in the Simulator Preferences. The

units are the user defined Output Units which can be millimeters, inches, degrees or radians.

Chassis

These are the points that are fixed to the Chassis. This includes A-Arm, Wishbone and Strut mounting points as well

as Spring and Damper chassis attachment points

Upright/Spindle

These are the points that are fixed to the Upright or Spindle. This includes outboard A-Arm, Wishbone and Strut mounting points as well as the Tie-Rod Upright attachment point

Axle

These are the points that are fixed to the Axle on the rear suspension types with a live axle. This includes Arm, Watts Linkage and Track Bar attachment points.

Wheel

These are the points that are fixed to the Wheel. This includes the Tire contact Patch, as well as the inner and outer wheel axis points.

Steering

These are the points that are fixed to the Steering System. This includes the inboard Tie-Rod points as well as the points of the linkages used in Recirculating-Ball Steering.

Non-Suspended Mass

These are the points that are fixed to the Non-Suspended Mass but are not fixed to the Wheel, Upright or Rocker. This includes Push/Pull Rod, Spring and Damper suspension attachment points.

Rocker

These are the points that are fixed to the Rocker. This includes the Rocker Pivot and Axis points as well as CoilOver and Drop Link Rocker attachment points.

Anti-Roll Bar/Sway Bar

These are the points that are fixed to the Anti-Roll Bar. This includes Anti-Roll Bar chassis Pivot and Axis points as well as Drop Link Attachment points.

Points Referenced from Upright Origin

The Points Referenced from Upright Origin outputs display the X, Y and Z coordinates of all the points that are located on the wheel and upright relative to the Upright Origin.



Output Channels/Link Lengths

[Page Name]

The Link Lengths output displays the length of the links that are used to make up the suspension.

Double A-Arm/Nascar Front

Lower Arm (Fore) – Distance from the Lower Arm Chassis Fore point to the Lower Arm Upright point.

Lower Arm (Aft) – Distance from the Lower Arm Chassis Aft point to the Lower Arm Upright point.

Upper Arm (Fore) – Distance from the Upper Arm Chassis Fore point to the Upper Arm Upright point.

Upper Arm (Aft) – Distance from the Upper Arm Chassis Aft point to the Upper Arm Upright point.

Tie Rod – Length of the Tie Rod link.

Push/Pull Rod – Length of the Push/Pull Rod.

Drop Link – Length of the Anti-Roll Bar Drop Link.

Mac Pherson

Wishbone (Fore) – Distance from the Wishbone Chassis Fore point to the Lower Arm Upright point.

Wishbone (Aft) – Distance from the Wishbone Chassis Aft point to the Lower Arm Upright point.

Tie Rod – Length of the Tie Rod link.


Nascar Rear

Truck Arms – Distance from the Truck Arm Chassis point to the Truck Arm Axle attachment point.

Panhard Bar – Length of the Panhard Bar.

V8 Supercar

Upper Trailing Arms – Length of Upper Trailing Arm.

Lower Trailing Arms – Length of Lower Trailing Arm.

Watts Link – Distance from Watts Link Rocker point to the Watts Link Axle attachment point.



Five Links

Link 1 – Length of Link 1.





Push/Pull Rod – Length of the Push/Pull Rod.




Output Channels/Wheel

Camber

Camber angle is the angle between the tilted wheel plane and the vertical. Negative camber is defined as the wheel plane being tilted towards the centerline of the vehicle. While positive camber is defined as the wheel plane being

tilted away from the centerline of the car.

Toe Angle

Toe angle is the angle between the wheel plane and the longitudinal axis of the vehicle. Positive toe (toe out) is when the front of the wheels are steered outwards while negative toe (toe in) is when the front of the wheels are

steered inwards.


Toe Distance

Toe distance is the same as toe angle except it is measured as a distance rather than an angle. Toe distance is the

lateral distance from the trailing Rim Edge to the leading Rim Edge. Positive toe (toe out) is when the front of the wheels are steered outwards while negative toe (toe in) is when the front of the wheels are steered inwards. Toe

distance is useful when setting the static toe angle using string lines.


Half Track

The half track is the distance between the center of the tire contact patch and the longitudinal axis of the vehicle.

OptimumK also outputs the halftrack that is measured from the wheel center to the longitudinal axis of the vehicle.

Steer Angle

Steer angle is the total wheel toe angle minus the static toe angle. Positive steer angle is when the front of the wheels are steered outwards more than when the suspension is in static conditions while negative steer angle is


when the front of the wheels are steered inwards more than when the suspension is in static conditions. Zero steer

angle is when the total wheel toe angle equals the static toe angle.

Wheelbase

The wheel base is the distance from the center of the front contact patch to the center of the rear contact patch.

The wheelbase on either side of the car can vary as the suspension is put through a motion.



Output Channels/Upright

Caster Angle

Caster angle when viewed from the side of a vehicle is the angle that the steering axis makes with the vertical. Positive caster is when the steering axis is tilted backwards while negative caster is when the steering axis is tilted

forwards.

Mechanical Trail

Mechanical trail is the distance from where the steering axis intersects the ground to the center of the Tire Contact

Patch when viewed from the side of the vehicle.

King Pin Angle


King Pin angle when viewed from the front of a vehicle is the angle that the steering axis makes with the vertical.

Positive King Pin angle is when the steering axis is tilted inwards while negative King Pin angle is when the steering axis is tilted outwards.

Scrub Radius

Scrub Radius is the distance from where the steering axis intersects the ground to the center of the Tire Contact

Patch when viewed from the front of the vehicle.

King Pin Axis Ground Point

The King Pin Axis Ground Point is the X, Y and Z coordinate of the intersection point between the King Pin Axis and the ground plane.



Output Channels/Axis/Instant Axis

Instant Axis

The Instant Axis is the axis which the Non-Suspended Mass rotates around as the suspension articulates. Each

corner of the car has its own Instant Axis. The Instant Axis is located by moving the wheel up and down by a small increment and then determining the point about which the wheel rotates. This method takes into account all links in

a suspension including any tie-rods or steering links.

Instant Center –Front View

The Front View Instant Center Point is where the Instant Axis intersects a vertical plane between the two front or

rear tire contact patches.

Instant Center – Side View

The Side View Instant Center Point is where the Instant Axis intersects a vertical plane between the two left or right tire contact patches



Output Channels/Axis/Swing Arms

Front Virtual Swing Arm Length

This is the lateral distance from the Tire Contact Patch to the Front View Instant Center Point.

Front Virtual Swing Arm Length vs Track

This is the FVSAL divided by the Track Width.

Side Virtual Swing Arm Length

This is the longitudinal distance from the Tire Contact Patch to the Side View Instant Center Point.

Side Virtual Swing Arm Length vs Wheelbase

This is the SVSAL divided by the Wheelbase.



Output Channels/Axis/Roll & Pitch Axis

Roll Center

The Roll Center is the intersection point between the left and right planes, which are defined by the instant axis and

contact patch point, and the vertical plane between the left and right contact patches. This Point is not stationary, it can move as the suspension articulates.

Roll Axis

The Roll Axis is a line drawn between the Front and Rear Roll Centers. This is the axis about which the Suspended

Mass rotates around. This axis is often called the Kinematics Roll Axis.


Pitch Center

The Pitch Center is the intersection point between the front and rear planes, which are defined by the instant axis

and contact patch point, and the vertical plane between the front and rear contact patches. This Point is not stationary, it can move as the suspension articulates.

Pitch Axis

The Pitch Axis is a line drawn between the left and right Pitch Centers. This is the axis about which the Suspended

Mass pitches about. This axis is often called the Kinematics Pitch Axis.



Output Channels/Axis/Colinearity of Front and Rear Roll Axes

[Page Name]

Angle Between Axes

This is the minimum angle between the front and rear roll axes. The front roll axis is the intersection of a plane defined by the left front instant axis and contact patch and a plane defined by the right front instant axis and contact

patch. The rear roll axis is the intersection of a plane defined by the left rear instant axis and contact patch and a plane defined by the right rear instant axis and contact patch.

Minimum Distance

This is the minimum distance between the front and rear roll axes.

Colinearity Percent

When the front and rear roll axes are parallel the colinearity percent equals 100%. When the front and rear roll axes

are perpendicular (angle between axes equals 90 degrees) the colinearity percent equals 0%.


Output Channels/Actuation

Coilover/Spring/Damper Length

This is the length of the Coilover, Spring or Damper from the Chassis attachment point to the Suspension Attachment point.

Coilover/Spring/Damper Displacement

This is the difference between the instantaneous Coilover, Spring or Damper length and the static Coilover, Spring or Damper length. A positive displacement is when the Coilover, Spring or Damper is longer than in static conditions

while a negative displacement is when the Coilover, Spring or Damper is shorter than in static conditions.


Rocker Angle

This is the rotation angle of the Rocker. Zero Rocker angle is when the Rocker is in a static condition.

SlideBar Displacement

This is the lateral movement of the slidebar when using a suspension with a Sliding Monoshock.


Rocker-Push/Pull Rod Angle

This is the angle between the Rocker plane and the Push/Pull Rod.

Rocker-Coilover Angle

This is the angle between the Rocker plane and the Coilover.



Output Channels/Anti-Roll Bar

[Page Name]

ARB Angle

This is the angle of twist in the Anti-Roll Bar Shaft compared to static conditions.

Rocker Angle

This is the rotation angle of the Anti-Roll Bar Rocker when using the U-Bar with Intermediate Rocker type Anti-Roll

Bar. Zero Rocker angle is when the Rocker is in a static condition.


Rocker-Drop Link Angle

This is the angle between the Rocker plane and the Drop Link.



Output Channels/Steering

%Ackerman

%Ackerman is calculated using the following formula.

Inside Steer vs Outside Steer

This is inside wheel steer angle divide by the outside wheel steer angle. A ratio of 1 means that the inside wheel will

have the same steer angle as the outside wheel for a given steering wheel input. If the ratio is less than 1 the inside

wheel will have a smaller steer angle than the outside wheel for a given steering wheel input. If the ratio is greater than 1 the inside wheel will have a larger steer angle than the outside wheel for a given steering wheel input.


Turn Instant Center

The turn instant center is found by modeling the vehicle as a bicycle model where the front and rear toe angles are

equal to the average of the corresponding left and right wheel toe angles. Two lines are drawn perpendicular to the front and rear wheel center planes. The intersection of these two lines is the turn instant center.

Turn Instant Radius

The turn instant radius is the distance from the turn instant center to the middle of the wheelbase.



Output Channels/Motion Ratio/Wheel

Spring

This motion ratio is wheel displacement divided by spring displacement (e.g. a ratio of 0.5 means that for every

1mm/in of wheel displacement the spring will displace by 2mm/in). The wheel displacement is the combined X, Y and Z displacement of the tire’s contact patch relative to the chassis. The spring displacement is measured along the

axis of the spring (line drawn from spring attachment to chassis points). This motion ratio is calculated at each step

of the simulation by raising and lowering the associated wheel by a given amount and then calculating the motion ratio based on the spring displacement.

Damper

This motion ratio is wheel displacement divided by damper displacement (e.g. a ratio of 0.5 means that for every

1mm/in of wheel displacement the damper will displace by 2mm/in). The wheel displacement is the combined X, Y and Z displacement of the tire’s contact patch relative to the chassis. The damper displacement is measured along

the axis of the damper (line drawn from damper attachment to chassis points). For Coilovers the damper axis is a line drawn from spring attachment to chassis points. This motion ratio is calculated at each step of the simulation by

raising and lowering the associated wheel by a given amount and then calculating the motion ratio based on the

damper displacement.

ARB - Dist

This motion ratio is wheel displacement divided by anti-roll bar displacement (e.g. a ratio of 0.5 means that for every 1mm/in of wheel displacement the anti-roll bar will displace by 2mm/in. The wheel displacement is the combined X,

Y and Z displacement of the tire’s contact patch relative to the chassis. The anti-roll bar displacement is the total displacement of the lever arm(s). This motion ratio is calculated at each step of the simulation by raising and

lowering the associated wheel by a given amount and then calculating the motion ratio based on the anti-roll bar

displacement.


ARB - Angle

This motion ratio is wheel displacement divided by anti-roll bar Angle (e.g. a ratio of 0.5 means that for every

1mm/in of wheel displacement the anti-roll bar will rotate by 2 deg/rad. The wheel displacement is the combined X, Y and Z displacement of the tire’s contact patch relative to the chassis. The anti-roll bar angle is the rotation

displacement of the anti-roll bar’s lever arm around the shaft. This motion ratio is calculated at each step of the

simulation by raising and lowering the associated wheel by a given amount and then calculating the motion ratio based on the anti-roll bars angular displacement.


Output Channels/Motion Ratio/Roll

Spring

This motion ratio is chassis roll angle divided by spring displacement (e.g. a ratio of 0.5 means that for every 1 deg/rad of roll the spring will displace by 2mm/in). The chassis roll is the roll motion that is applied to the chassis.

The spring displacement is measured along the axis of the spring (line drawn from spring attachment to chassis

points). This motion ratio is calculated at each step of the simulation by rolling the chassis by a given amount and then calculating the motion ratio based on the spring displacement.

Damper

This motion ratio is chassis roll angle divided by damper displacement (e.g. a ratio of 0.5 means that for every 1

deg/rad of roll the damper will displace by 2mm/in). The chassis roll is the roll motion that is applied to the chassis. The spring displacement is measured along the axis of the spring (line drawn from spring attachment to chassis

points). For coilovers the damper axis is a line drawn from spring attachment to chassis points. This motion ratio is

calculated at each step of the simulation by rolling the chassis by a given amount and then calculating the motion ratio based on the damper displacement.

ARB - Dist

This motion ratio is chassis roll divided by anti-roll bar displacement (e.g. a ratio of 0.5 means that for every

1deg/rad of chassis roll the anti-roll bar will displace by 2mm/in. The chassis roll is the roll motion that is applied to the suspension. The anti-roll bar displacement is the total displacement of the lever arm(s). This motion ratio is

calculated at each step of the simulation by rolling the chassis by a given amount and then calculating the motion

ratio based on the anti-roll bar displacement.


ARB - Angle

This motion ratio is chassis roll angle divided by anti-roll bar Angle (e.g. a ratio of 0.5 means that for every 1

deg/rad of roll the anti-roll bar will rotate by 2 deg/rad. The chassis roll is the roll motion that is applied to the chassis. The anti-roll bar angle is the rotation displacement of the anti-roll bar’s lever arm around the shaft. This

motion ratio is calculated at each step of the simulation by rolling the chassis by a given amount and then calculating

the motion ratio based on the anti-roll bar angular displacement.


Output Channels/Motion Ratio/Heave

Spring

This motion ratio is chassis heave divided by spring displacement (e.g. a ratio of 0.5 means that for every 1mm/in heave displacement the spring will displace by 2mm/in). The chassis heave is the heave motion that is applied to the

suspension. The spring displacement is measured along the axis of the spring (line drawn from spring attachment to chassis points). This motion ratio is calculated at each step of the simulation by raising and lowering the chassis by a

given amount and then calculating the motion ratio based on the spring displacement.

Damper

This motion ratio is chassis heave divided by damper displacement (e.g. a ratio of 0.5 means that for every 1mm/in

heave displacement the damper will displace by 2mm/in). The chassis heave is the heave motion that is applied to the suspension. The damper displacement is measured along the axis of the damper (line drawn from damper

attachment to chassis points). For Coilovers the damper axis is a line drawn from spring attachment to chassis points. This motion ratio is calculated at each step of the simulation by raising and lowering the chassis by a given

amount and then calculating the motion ratio based on the damper displacement.

ARB - Dist

This motion ratio is chassis heave divided by anti-roll bar displacement (e.g. a ratio of 0.5 means that for every

1mm/in of chassis heave the anti-roll bar will displace by 2mm/in. The chassis heave is the heave motion that is applied to the suspension. The Anti-roll bar displacement is the total displacement of the lever arm(s). This motion

ratio is calculated at each step of the simulation by raising and lowering the chassis by a given amount and then calculating the motion ratio based on the anti-roll bar displacement.


ARB - Angle

This motion ratio is chassis heave divided by anti-roll bar Angle (e.g. a ratio of 0.5 means that for every 1mm/in of

chassis heave the anti-roll bar will rotate by 2deg/rad. The chassis heave is the heave motion that is applied to the suspension. The Anti-roll bar angle is the rotation displacement of the anti-roll bar’s lever arm around the shaft. This

motion ratio is calculated at each step of the simulation by raising and lowering the chassis by a given amount and

then calculating the motion ratio based on the anti-roll bar angular displacement.


Suspension Design Tips

[Page Name]

This section will guide you through the basic techniques on how to design good suspension kinematics. For more

advanced detailed explanations please attend one of Claude Rouelle’s “Race Car Vehicle Dynamics” seminars. For

more information please visit www.optimumg.com

Process

The following steps are required to design good suspension kinematics.

• Wheelbase and Tracks

• Wheel Packaging (Rim, Tire, Brake Caliper)

• KPI and Caster (Angle and Trail)

• Roll Center (Lateral weight transfer, Track changes)

• Lateral VSAL (Camber Change)

• Pitch Center (Longitudinal weight transfer)

• Bump Steer

• Ackermann

Suspension kinematic design is an iterative process that requires many compromises to be made before obtaining a

good result.


Suspension Design Tips/Wheelbase & Tracks

[Page Name]

Wheelbase and tracks are the first parameters to be set because they determine the total packaging constraints.

Things to consider when choosing a wheelbase and track;

• Lateral weight transfer

• Longitudinal weight transfer

• Yaw moment of inertia

• Aerodynamics

• Packaging

• Type of car

• Type of race track

• Rules

Weight transfer

Total weight transfer (i.e. geometric + elastic weight transfer) is a function of track width (lateral) and wheelbase

length (longitudinal). A wide track will cause less lateral weight transfer during cornering. A long wheelbase will

cause less longitudinal weight transfer in braking and accelerating. Weight transfer is undesirable because of tire load sensitivity. Tire load sensitivity is the falling rate of its lateral or

longitudinal grip when placed under an increasing vertical load for a given slip angle. This means that as the vertical load on a tire increases it’s lateral and longitudinal grip increase by a smaller gradient.

Yaw Moment of Inertia


An increase in track or wheelbase will cause the masses of the non-suspended components (e.g. rim, tire, hub,

upright, brake etc.) to be placed further from the centre of gravity of the car. This will increase the cars yaw moment of inertia.

A cars ideal yaw moment of inertia is a compromise between “stability” and “response”. The best compromise between stability and response depends on the circuit the car is racing on.

Type of Situation Best Configuration Comments

Fast/Large radius sweepers Long Wheelbase

Wide Track

Stable platform

Less weight transfer

Tight hairpins, Chicanes or Slaloms Small wheelbase Track as large as possible (rules,

circuit etc.)

Unstable platform Good transient response

Circuits with very long straights Long wheelbase Added stability for aerodynamic and road disturbances at high

speed. Increased braking performance

Aerodynamics

The frontal area of the car will be affected by the chosen track width. An increase in track width will cause an

increase in drag. Track changes in open wheel race cars will affect the entire flow pattern of the car.

Packaging

Clearance between wings, end plates and wheel arches will influence wheelbase and track dimensions.

Half Track Variations

The half track will change as the suspension articulates. How much it changes will depend on the suspension’s

geometry. As the half track changes during a motion the tire is forced to move laterally. If the half track changes a by a large amount the tire will slide across the road surface. This will lead to increased tire temperature and

premature tire wear.


Wheelbase Variations

Excessive wheelbase changes during the roll, pitch and heave motions can cause irregular handling behavior. Wheelbase variations are caused by suspension geometry that causes the wheels to move forward or backward as

the suspension articulates.

TD_WheelbaseGraph.jpg


Suspension Design Tips/Wheel Packaging

[Page Name]

The rim dimensions are usually defined by the tires that are available for a given type of race car or class.

Rim widths and offsets will influence;

• Scrub radius

• Maximum steer angle

• Bending loads in hub

• Bearing loads

The rim diameter will influence the packing of;

• Toebase length

• Outboard brake disc size


Suspension Design Tips/KPI & Caster

[Page Name]

Caster and King Pin Inclination (KPI) are used to define the location and angle of the steering axis (also known as the King Pin Axis) from the tire contact patch.


Caster & KPI Angle

Caster and KPI angle will cause the tire to camber as it is steered about the steering axis. The amount and direction

that the tire will camber is given by the following formula.

∆ Camber = KPI (COS(Steering Angle)) + Caster (SIN(Steering Angle))

Because camber change is related to the Cosine of the steering angle the direction of the camber change will always

have the same sign as the KPI angel on both inside and outside wheel. Since camber change is related to the Sine of the steering angle the direction of the camber change will be opposite on both the inside and outside wheels.

Negative Caster Positive Caster Negative KPI Positive KPI

Inside Wheel Gains negative

camber

Gains positive

camber

Gains negative

camber

Gains positive

camber

Outside Wheel Gains positive camber

Gains negative camber

Gains negative camber

Gains positive camber

Caster and KPI angle will vary the following parameters when the wheels are steered • Tire KPI Trail

• Tire Caster Trail

• Camber

• Ride Heights

• Roll Angle

• Rake Angle

• Corner Weights

• Track Width (only of wheels being steered)

• Wheelbase (Left and Right)

Mechanical Trail & Scrub Radius

Mechanical trail is the distance from where the steering axis intersects the ground to the tire contact patch when

viewed from the side of the vehicle. While Scrub radius is the distance from where the steering axis intersects the ground to the tire contact patch when viewed from the front of the vehicle.

The location of where the steering axis intersects the ground will determine the forces in the steering linkages. If the

intersection point is offset from the tire contact patch the lateral and longitudinal grip on the tire will create a torque

at intersection point which will generate a force in the steering linkages. The point where the steering axis intersects the ground is defined by the Mechanical Trail and Scrub Radius.


The larger the mechanical trail and scrub radius the more effort that is required to steer the wheels. Too large a mechanical trail and scrub radius will cause heavy steering. While too small a mechanical trail and scrub radius will

cause steering with little feel and feedback.


Suspension Design Tips/Roll Axis

[Page Name]

The roll axis is a line drawn between the front and rear roll centers. This is the axis about which the suspended mass rotates about. This axis is often called the kinematics roll axis.

Roll Axis Height

A roll axis that is above the ground will; • Decrease roll

• Increases jacking

• Instant geometric transfer loads the outside tire and unloads the inside tire

• Lower suspended mass inertia

• Improves turn in

• Increase ride height

A roll axis that is under the ground will; • Increase roll

• Create anti jacking

• Instant geometric transfer loads the inside tire and unloads the outside tire

• Higher suspended mass inertia

• Diminish turn in response and

• Lower ride height

Roll Axis Inclination

The height of the front and rear roll centers will affect how the roll moment is distributed between the front and rear

wheels. If the rear roll center is higher than the front there will be a larger roll moment on the rear tires this will lead to a larger geometric weight transfer on the rear axle that will cause the rear tires to become more unevenly loaded

during a corner and hence have less lateral grip. Raising and lowering the front and rear roll centers will alter the

understeer-oversteer characteristics of the car.


Roll Axis Lateral Movement

As the suspension rolls the roll axis will move lateral. How much it moves will depend on the suspension geometry.

The Roll axis can skew because of different front and rear suspension geometry and roll angles.

A roll center that is closer to one side of the car and inside the track, is like having a stiffer springs on that side of the car and a softer spring on the other side.


Suspension Design Tips/FVSAL

[Page Name]

The Front View Swing Arm Length (FVSAL) determines the camber change of the tires during Pitch, Heave and Roll.

Long FVSAL Short FVSAL

Pitch & Heave Small camber change Large camber change

Roll Large camber change Small camber change

Because maximum longitudinal and lateral grip generally occur at different camber angles the ideal FVSAL length is a

compromise between lateral and longitudinal grip. Your tire data will decide how to make a compromise between camber variation in heave and roll. This compromise will depend on the type and shape of the circuit being raced on.


Suspension Design Tips/Pitch Axis

[Page Name]

The pitch axis is a line drawn between the left and right pitch centers. This is the axis about which the suspended mass pitches about. This axis is often called the kinematics pitch axis.

Pitch Axis Location

The location of the pitch axis will determine the Anti Lift, Squat and Dive properties. The Anti properties determine

how front and rear suspensions behave during braking and acceleration. The Anti properties will depend on the drive (FWD, RWD, 4WD) and brake (inboard or Outboard) layout of the car.

Pitch Axis Longitudinal Movement

As the suspension pitches the pitch axis will move longitudinally. How much it moves will depend on the suspension geometry.


A pitch center that is closer to one end of the car and inside the wheelbase, is like having a stiffer springs at that end

of the car and a softer spring on the other end of the car.


Suspension Design Tips/Bump Steer

[Page Name]

Bump steer is when the toe angle of the wheel changes as the suspension goes from full bump to full droop. Bump steer is generally undesirable because it causes the car to self steer as it goes over bumps and undulations on the

race track.

Causes of Bump Steer

Bump steer occurs when the tie rod axis does not intersect the Instant Center throughout the full range of

suspension movement.

Benefits of Bump Steer

Bump steer (also known as “roll steer”) can be used to change the toe angle of the wheels during pitch and roll. As

the car rolls in a corner bump steer will cause the wheels to change toe angle and hence slip angle as the car goes through a corner. This can be used to increase the grip on the un-steered tires if they have not already exceeded

their maximum available grip.


Suspension Design Tips/Ackermann

[Page Name]

Ackermann steering is when all four wheels travel along an arc that has a common Instant center.

Pro-Ackermann

Pro-Ackermann steering is when the front wheels have a larger combined steer angle than Ackermann steering. Pro-

Ackermann is useful on tracks with lots of low speed tight corners.

Anti-Ackermann

Anti-Ackermann steering is when the front wheels have a smaller combined steer angle than Ackermann steering. A

race tire’s maximum lateral grip for a given vertical load generally occurs at higher slip angles as the vertical load increases. This means that for both the inside (less vertical load) and outside (more vertical load) tire to be at their

maximum available grip the outside tire needs to be at a higher slip angle than the inside tire. Anti-Ackermann

achieves this by causing the outside tire to be at a larger steer angle than the inside tire.


Feedback

OptimumK is a continually developing program and we give high regard to any comments, complaints or criticisms that OptimumK users might have. Please contact us at [email protected] and we will endeavor to

improve OptimumK based on your feedback.

OptimumK Help File

Documents

Transcript of OptimumK Help File