vehicle proving ground durability performance simulation using flexible multi-body dynamic modal...

MSC Software Confidential 2012 International Ground Vehicle Users Symposium

Vehicle Proving Ground Durability Performance Simulation using

Flexible Multi-Body Dynamic Modal Stress Synthesis Method

2012 International Ground Vehicle Users Symposium

Presented By:

Maolin Tsai

General Motors Company

October 19, 2012


Objectives

Flow Chart of the Flexible Multi-Body Dynamic Modal Stress

Synthesis for Dynamic Durability Analysis

Flexible Multi-Body Dynamic Durability Analysis in Chassis

Applications

Methodologies Verification: Fatigue Damage

Motivations: Failure Mode Correlation

Accelerated Test Development

Conclusions

Outline

2


Dynamic stress simulation to account

for inertia effect (dynamic equilibrium &

satisfy both the geometric (critical for

component with large deformation or

rigid body motion articulation) and force

boundary conditions .

Inertia Relief based fatigue analysis (may mislead design)

Examples: compound crank rear axle &

suspension links

FEA-based modal or direct transient fatigue analysis (not practical)

Practical and efficient approach for

dynamic fatigue analysis & synthesis.

No additional simulation effort is

required compared with traditional

dynamic load prediction

(incorporating flexible body into

multi-body dynamic model)

Objectives

3

Effective structural design for durability

optimization.

Standard quasi-static design loads

Road load based duty cycle loads

Accelerated laboratory development.

Multi-axial subsystem block cycle test

(instead of using RPC test) or

component bench tests


Flow Chart of Duty Cycle Flexible Multi-Body

Dynamic Durability Analysis

4

Multi-body dynamic model for vehicle durability load

prediction

Build up flexible multi-body dynamic model (w/mtx file); and with modal stress requested in FE solver for post-process

Vehicle proving ground durability road

load schedules

(i) Interface joint loads/disp. output (ii) Modal coordinate output

Flexible body dynamic stress history output

Duty cycle modal frequency fatigue

analysis

Fatigue material data base

Modal stress synthesis


Flexible Multi-Body Dynamic Modal Stress Synthesis

for Chassis Durability Application Examples

5

Theory: Craig-Bampton Component Mode Synthesis (CMS)

It combines the motion of joint interfaces with normal modes of the structural components

Front Cradle and Rear Compound Crank Independent Suspension Links


Dynamic Rear Links Stress Animation of Pothole Load

6


Full Vehicle Dynamic Stress Animation of

Rough Road Event

7


Methodologies Verification

8

Fatigue analysis using flexible multi-body

dynamic modal stress synthesis Fatigue analysis using modal

transient method

Good Correlation:

The peak damage ratio between the two methods is 1: 1.6

Torsional Beam Fatigue Damage Correlation


Motivations: Failure Mode Correlation

9

critical location predicted

using inertia relief

stress analysis

critical location predicted using

Flexible multi-body dynamic

modal stress synthesis

Spring Block Cycle Load

(cant correlate test failure mode) Spindle Lateral Load (Modal Stress Synthesis)

(correlate test failure mode)

1. Dynamic Inertia Effect

2. Boundary Conditions


Application: Multi-Axial Subsystem Block Cycle

Accelerated Test Development

10

Integration of Flexible Multi-Body Dynamic, Fatigue and Optimization in Accelerated Test Development

Baseline Road Loads Structural Damage

(i) Wheel Forces & Suspension Interface

Pseudo-Fatigue Damage

(ii) Structural Fatigue Damage

Using ADAMS/Flex Modal

Frequency Method

(ADAMS/Flex Modal Frequency Method) (ADAMS/Flex Modal Frequency Method)


Application: Multi-Axial Subsystem Block Cycle

Accelerated Test Development (Cont.)

11

Rig Test Input: 10 channels Wheel Force

Damage Correlation of Rig Test Interface Loads


Conclusions

The flexible multi-body dynamic modal stress based durability

analysis and synthesis is a key enabler for vehicle durability

development process in terms of efficiency and effectiveness.

The amount of extra computation time and effort is low and yet the accuracy of life prediction is greatly enhanced compared to

traditional methods.

Multi-axial subsystem block cycle accelerated test using this methodology can significantly reduce test time (compared with RPC

test) and still retain the damage content in the critical locations.


Contributors

13

Hyung-Joo Hong

Robert L. Geisler

Glenn Babiak

General Motors Company

vehicle proving ground durability performance simulation using flexible multi-body dynamic modal...

Documents