DoE & Optimization in Automotive MBS Simulation Tasks · MBS Model MBS Solver 8.11.2011 Reinalter,...

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DoE & Optimization in Automotive MBS Simulation Tasks

2011 European HyperWorks Technology Conference, Nov. 8th, Bonn, Germany

SuspensionAnalysis

&

Vehicle Handling

ComfortSimulation

Consistent Mechatronic Vehicle Model

mechatronic

Application of MBS


Calculation ofStatic & Dynamic

Loads

Calculation of Package Demand

mechatroniccomponent

Content

1. Introduction and calculation process

• Initial point & mission

• Process overview

• Used software

2. Example: driving comfort �� design of engine mount systems

• Problem definition

• Engine mount system � creation of coupled / decoupled variants



• Relative comparison of different variants

• Summary

3. Conclusions and further work

Initial Point

Mission (some years ago):

Highlight the influence of vehicle configurations and testing parameters to rollover behaviour.

�� Long time running simulation.

�� Huge number of simulation runs.


�� Automated simulation and data analysis process needed.

Process Overview

User defined

Parameters

Manoeuvres

Vehicle Configurations

Module Properties

Component Properties

MBS Solver

Data Analysis

MBS Model


Results

Process Overview

DoEStochastic approach

Systematic approach

OptimizationNumerical

optimization

User defined

Parameters

Manoeuvres


Module Properties


MBS Solver

Data Analysis

MBS Model


Results

DoE Correlation Coefficients

Optimization

Data Analysis

DoEStochastic approach

Systematic approach

OptimizationNumerical

optimization

User defined

Parameters

Manoeuvres


Module Properties


ALTAIR Hyperstudy® MSC.ADAMS/Car®

Python®

Used Software

MBS Model

MBS Solver


Results

DoE Correlation Coefficients

Optimization

National Instruments - DIAdem®

Python

Content




• Used software







• Summary


Problem Definition

Increased relevance of engine mount system design due to:

• trend towards lighter car bodies (body in white) and more power-intensive engines

• trend towards 3Zylinder / 2Zylinder engines �� engine torque fluctuation gets more important

• front wheel driven vehicles with low idle speed

Investigations considering the design & analysis of engine mount systems:

engine rigid body modes ( frequencies, coupling of modes)


• engine rigid body modes (�� frequencies, coupling of modes)

• engine excitation (gas forces �� acceleration at seat rail and mount positions at body)

• road excitation (�� acceleration at seat rail and mount positions at body)

Engine Mount System

Is it possible to use the modal coupling as a reliable indicator of the performance of

an engine mount system?

Hypothesis:

• Decoupling of engine rigid body modes increases comfort for engine excitation

• Coupling of engine rigid body modes increases comfort for road excitation

� Finding coupled & decoupled engine mount systems by means of DoE and


� Finding coupled & decoupled engine mount systems by means of DoE andnumerical optimization by using modal kinetic energy

� Calculation of engine and road excitations and judge accelerations at seat rail and body-sided mount positions

Definition of Modal Kinetic Energy

Modal matrix with Eigenvectors

Reduced modal matrix considering degrees of freedom of part j

Modal kinetic energy of mode i

Modal kinetic energy of part j considering mode i

Thereby is the ith column vector of the reduced modal matrix


0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

33 32 31 35 34 36

rz

ry

rx

z

y

x

� Modal kinetic energy of part “engine”

separated for six rigid-body engine modes

(number 31...36) and in translational &

rotational directions.

� Result of a first DoE is a strongly coupled

version of engine mount system

Optimization Loop

� Optimization criteria is maximum of purity

for each mode by using modal kinetic

energy values

� Parameters: mount positions, mount

stiffness and damping values

� Algorithm: ARSM

� Calculation time: ~17min


� Result of numerical optimization is a well

decoupled version of engine mount system,

regarding rigid-body engine modes

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1 2 3 4 5 6

rz

ry

rx

z

y

x

Engine / Road Excitation

coupled decoupled

MSF rough road + -


MSF rough road + -

Public highway + -

Rough asphalt + -

Cobblestone pavement + -

Single obstacle + -

3rd gear runup - +

Idle run - +

Result of virtual road simulation

� Acceleration at driver seat rail (vertical direction)

� Relative comparison of different variants

Engine / Road Excitation

basicversions with comparable

frequencies

versions with samestiffness / loss angle

coupled decoupled coupled FRQ

decoupledFRQ

coupledSTIFF

decoupledSTIFF

coupled½ STIFF

decoupled½ STIFF

MSF rough road + - ~ ~ + -


MSF rough road + - ~ ~ + -

Public highway + - + - + -

Rough asphalt + - ~ ~ + -

Cobblestone pavement + - + - + -

Single obstacle + - ~ ~ + -

3rd gear runup - + - + + - - +

Idle run - + - + - + - +

Summary – Engine Mount System Design

Conclusion:

Shown results support Hypothesis:

• Even if considering comparable rigid engine/gearbox pitch frequency (RY) or comparable stiffness levels:

� decoupling decreases body-accelerations for engine excitation

� coupling decreases body-accelerations for road excitation


• Using modal kinetic energies offers possibility to tune an engine mount system as desired (improve comfort for road- or engine-excitation) in a very fast way

• With additional boundaries (e.g. eigenfrequency of engine pitch mode should be low) optimized compromise solutions are possible

Content




• Used software







• Summary


Conclusion:

• “Automated” simulation process successfully launched.

• For different areas of MBS application at MAGNA Steyr, e.g. comfort simulation � design of

engine mount systems the application of numerical DoE and optimization methods certainly offers the possibility to accelerate the design process significantly.

• Nevertheless the “push the button and get the optimal design” approach seems to be out of reach.

Conclusions and further work


reach.

Further work:

• “Plug-and-play” process for mechatronic models (by using co-simulation MATLAB <-> ADAMS/Car) will be ready by end of this year.

• Further investigations on target conflict between vehicle handling and driving comfort will be done by using numerical DoE and optimization methods – on going work.

Thank you very much for your kind attention!


Contact Address:

Mr. Werner Reinalter

MAGNA Steyr Fahrzeugtechnik

Liebenauer Hauptstraße 317

[email protected]

www.magnasteyr.com

DoE & Optimization in Automotive MBS Simulation Tasks · MBS Model MBS Solver 8.11.2011 Reinalter,...

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