MESH MORPHING BASED SHAPEMESH MORPHING BASED SHAPE OPTIMIZATION OF A CLUTCH LEVER

Abaqus Global User Conference, 2004

Presented by:Ramesh Padmanaban, Ragavendran Vasudevan, , g ,

Radha Krishnan

Detroit Engineered Products, Inc.

Yogesh Wadhera – New Venture Gear

Mike Sheh – Engineous Inc.

Recent Trends in the CAE Industry

Significant improvements in computing hardware:High speed processorsHigh speed processorsNetworked/distributed computing etc.

Significant improvements in Solvers:Significant improvements in Solvers:Reduction in analysis execution timeParallel processing

Availabililty of process integration & automation tools:Ability to automate a routine CAE processy pCreation of automated workflows

Recent Trends in the CAE Industry

Availability of general purpose optimization programs:C d t i l d lti di i li ti i ti t di th tConduct single and multi-discipline optimization studies that utilize the automated workflowsCreate higher level ‘quick turn-around’ response surface modelsmodels

Availability of Morphing & Parametrization Tools:Ability to remove a key bottle neck in the optimization process, i.e, CAD dependencyRapid FE & CFD model generation – in a fraction of time taken b on entional methodstaken by conventional methods

Role of Design Exploration & Optimization

With these trends, the CAE engineer is best positioned for:positioned for:

Conducting DOE studiesConduct Optimization studiesPerform design explorationPerform DFSS (Design for Six Sigma) studies

Clear move from ‘single point design study’ to designClear move from single point design study to design explorationGood positioning of the CAE engineers to truly lead p g g ythe design process

CAE TO LEAD THE DESIGN PROCESS

HARDWARE IMPROVEMENTS

SOLVER SPEED IMPROVEMENTS

CAE not just a validation toolInstead CAE will

IMPROVEMENTS IMPROVEMENTS

PROCESSInstead, CAE will lead the design

process

PROCESS AUTOMATION & OPTIMIZATION TOOLS

MORPHING & PARAMETRIZATION TOOLS

OPTIMIZED

TOOLS TOOLS

DESIGN

Different Shape Optimization ApproachesExplicit definition of nodal movement as design variables:

Rather cumbersome to set upLimited to small shape changes

Shape optimization with CAD in the loop:OPTIMIZER

New values of design parameters

PARAMETRIC CAD SYSTEM

ANALYSIS SOLVERSYSTEM

Regenerated CAD model (new design)

FE PRE-PROCESSOR

Is it OPTIMUM ?

YES

NO

FE PRE PROCESSOR (Auto-meshing)

FE model of the new design

STOP

Different Shape Optimization ApproachesRemeshing from CAD data not fully automatableIf FE model is an assembly comprising of different components and different types of elements remeshingcomponents and different types of elements, remeshing almost impossibleMay be limited to only shape parameters

Mesh Morphing based shape optimization processOPTIMIZER

N l f d iNew values of design parameters

MORPHER (FE/CFD Parametrization tool)

Analysis ready FE model ofAnalysis ready FE model of new design

ANALYSIS SOLVER

Is it OPTIMUM ?NO Is it OPTIMUM ?

STOP

YES

Different Shape Optimization ApproachesIn this process CAD model generation is completely eliminated from the optimization processModels generated by the Morpher are analysis readyProcess inherently robustLarge shape changes are possibleLarge shape changes are possible

Important stages in the Morpher based shape optimization process

Parametrization of the FE (or CFD) modelAnalysis Process AutomationOptimization

Parametrization: High Level Description

Linear Static Analysis Model

Non-linear Static Model

Model

MESHWORKS/MORPHER V3.0

Morphing and

Static Model

Noise & Vib ti d l

Parametrized Model Data BaseMorphing and

Parametrization ToolVibrations model

Crash ModelCrash Model

CFD ModelCFD Model

Types of Design Parameters

SHAPE STRUCTURALFEATURE GENERALSHAPE PARAMETERS

Cross-section of A-pillar

STRUCTURAL PARAMETERS

Thickness of shell structures

FEATURE PARAMETERS

Automated stiffener (bead) creation

GENERAL PARAMETERS

Air bag firing timepillar (stiffness/frequency)

Vent Opening width of Passenger Air Bag

shell structures

Cross-sectional properties of beam members

(bead) creation

Number of stiffener beads and their spacing

Friction coefficient

Column stroke

Stiffness curvePassenger Air Bag (occupant safety)

Front hood angle (external

beam members

Etc.

spacing

Automated punching of holes and slots

Stiffness curve

Etc.

(external aerodynamics)

Rail width & height (crashworthiness)

and slots

Etc.

(crashworthiness)

Tether length & connection location

Etc.

Parametrizing FE/CFD models

Parametrization of the FE/CFD Model/Use Morpher to parametrize existing FE/CFD modelsIntroduce shape, structural, feature and general parametersFE/CFD models become INTELLIGENT PARAMETRIC FE/CFD models

Creating a Design

Design A Design B

Design Design DesignDesign parameter A

Design parameter B

Design parameter C

Morph Set A Morph Set B Morph Set CMorph Set A Morph Set B Morph Set C

Control Zone

Deformation Zone

Fixed Zone

Concept of Parametric FE model (contd.)

DP3

DP1 L th d i i bl

DP2

DP1 – Length design variableDP2 – Height design variableDP3 – Width design variableDP4 – Radius design variable

DP1

DP4

DP1

DP1 – 3.5DP2 – 4 0 Design 1DP2 4.0DP3 – 1.2DP4 – 2.0

Parametrized FE model

g

DP1 – 4.0DP2 – 5.0DP3 – 2.0

Parametrized FE model

Design 2DP4 – 2.5

Optimization loop

DP1 Design 1

Design 2

P met i ed FE model

DP2

Design 3Parametrized FE model g

DP3

Design nDP4 Design nOPTIMUM

Loop 1 Loop 2 Loop 3 Loop n

Analysis Process Automation

Use an analysis process automation tool such as Isight to automate typical analysis process steps executed by the CAEautomate typical analysis process steps executed by the CAE engineerThese steps would typically include:

S b i i f h d l f l i AbSubmission of the model for analysis to AbaqusFrom the results generated, extract the specific output parameters such as maximum deflection, maximum stress, contact pressure etccontact pressure etc.Compute sensitivities of output parameters with respect to design variablesBased on sensitivities generate new values for design variablesBased on sensitivities, generate new values for design variablesExecute Morpher to generate analysis model of new designProceed with the next loop

A l i t ti i ti l f t t dAnalysis process automation is essential for automated optimization process

Optimization Methodology

Optimizationp

FEA Run timeResource & Project calendar timeNumber of Design ParametersNumber of Design ParametersDesign Space – Linear & Non-linear

A t t d R S f M d lAutomated Response Surface Model

Analysis Process Automation & Optimization set up

Meshworks/Morpher

Parametrization & shape change engine

Abaqus analysis

gAnalysis ready FE/CFD model with new shapeiSIGHT (Design

parameter values generation)

q y

NO

FE / CFD Analysis

iSIGHT outputParsing

Results extraction Conve

r-gence

Parsing

optimumYES

Optimization Loop (iSIGHT)

Batch Morpher Shape change

Abaqus Translation

Remote execution of Abaqus

iSIGHT waiting for Abaqus results

Results extraction

Remote deletion of old files

iSIGHT integration with Morpher – Design Parameter file

iSIGHT modifies the values of each design parameter in DP file. A samplefile is shown above. The logical way of automatically modifying the designparameter is using an optimization algorithm.

Results Extraction

iSIGHT extracts the results from the text output file ( from analysis ). A sample file is shown above

Presentation of actual case study – optimization of clutch lever

Objective function : Mi i i D fl ti i th l t h lMinimize Deflection in the clutch lever

Constraints :M i b li i tMaximum stress < baseline maximum stress

Design Variables: Shape of diffe ent feat es of the cl tch le eShape of different features of the clutch lever

Range of the design variables:Range based on manufacturability package space andRange based on manufacturability, package space and element quality constraints

Lever - Loads and BCTwo points arerigidly constrainedg yexcept for the rotationabout y axis

2 86KN

z axis translation is constrained

2.86KN

5.65KN

X axis

Z axis

Material = Cast Iron

Design Variables of the Clutch lever

Thickness of ribsThickness of ribs

Width of webWidth of web

Thickness of webThickness of web

Height of ribsHeight of ribs

Optimization – Design SpaceOptimization – Design Space

Results Review - Mass history plot

X 1000kg

Results Review - Maximum Von Mises stress history plot

MPa

Optimization Statistics

Multi-genetic global optimization scheme usedOptimum obtained after 80 loopsOptimum obtained after 80 loopsTotal completion time for Abaqus analysis, results extraction & morphing in each loop = 30 min.HPJ6700 machine used for analysisAfter obtaining optimum for maximum stiffness, a separate optimization was carried out to minimize massoptimization was carried out to minimize massResults are presented in the subsequent slides

Results of Optimization

Stiffness was improved about 25%Stress levels were maintained below the target of the materialStress levels were maintained below the target of the material yield strengthThere was marginal increase in weight

Results of Optimization for maximizing stiffnessShape change from original to Optimal design

Baseline design

Optimized design

Results of Optimization for minimizing massShape change from original to Optimal design

DV2BaselineOptimumOptimum

DV5 & DV7BaselineOptimumDV4

BaselineOptimum

Optimized design

Baseline design

DV5 & DV7BaselineOptimum

DV9BaselineOptimum

Baseline to Optimum

Conclusions

A robust mesh morphing based shape optimization process has been demonstratedIt can be effectively used on components with complex geometriesSignificant shape change has been effected in a robust manner using this processthis processThe process can be successfully implemented on large system level models with multi-disciplinary constraintsTh ti i d d l b t d t i t lith h (STL)The optimized model can be exported out in stereo-lithography (STL) file format, that can be imported into any CAD system, using which a detailed geometry can be builtU i hi h CAE i l l d h d iUsing this process, the CAE engineer can truly lead the design process