8.11.2011 Reinalter, Angrosch 1Disclosure or duplication without consent is prohibited

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

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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

8.11.2011 Reinalter, Angrosch 3Disclosure or duplication without consent is prohibited

• 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.

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���� 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

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Results

Process Overview

DoEStochastic approach

Systematic approach

OptimizationNumerical

optimization

User defined

Parameters

Manoeuvres

Vehicle Configurations

Module Properties

Component Properties

MBS Solver

Data Analysis

MBS Model

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Results

DoE Correlation Coefficients

Optimization

Data Analysis

DoEStochastic approach

Systematic approach

OptimizationNumerical

optimization

User defined

Parameters

Manoeuvres

Vehicle Configurations

Module Properties

Component Properties

ALTAIR Hyperstudy® MSC.ADAMS/Car®

Python®

Used Software

MBS Model

MBS Solver

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Results

DoE Correlation Coefficients

Optimization

National Instruments - DIAdem®

Python

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

8.11.2011 Reinalter, Angrosch 8Disclosure or duplication without consent is prohibited

• Engine mount system � creation of coupled / decoupled variants

• Relative comparison of different variants

• Summary

3. Conclusions and further work

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)

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• 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

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� 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

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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

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� 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 + -

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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 + - ~ ~ + -

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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

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• 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

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

8.11.2011 Reinalter, Angrosch 16Disclosure or duplication without consent is prohibited

• Engine mount system � creation of coupled / decoupled variants

• Relative comparison of different variants

• Summary

3. Conclusions and further work

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

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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!

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Contact Address:

Mr. Werner Reinalter

MAGNA Steyr Fahrzeugtechnik

Liebenauer Hauptstraße 317

werner.reinalter@magnasteyr.com

www.magnasteyr.com