Center for Computer Aided Design Automotive Research Center arc CAD-BASED DESIGN PROCESS FOR FATIGUE ANALYSIS, RELIABILITY- ANALYSIS, AND DESIGN OPTIMIZATION K.K. Choi, V. Ogarevic, J. Tang, and Y.H. Park Center for Computer-Aided Design College of Engineering The University of Iowa Iowa City, IA 52242
35
Embed
CAD-BASED DESIGN PROCESS FOR FATIGUE …arc.engin.umich.edu/events/archive/annual/conf98/choi.pdf · Center for Computer Aided Design arc Automotive Research Center CAD-BASED DESIGN
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Center for Computer Aided Design
Automotive Research Centerarc
CAD-BASED DESIGN PROCESS FORFATIGUE ANALYSIS, RELIABILITY-
ANALYSIS, AND DESIGN OPTIMIZATION
CAD-BASED DESIGN PROCESS FORFATIGUE ANALYSIS, RELIABILITY-
ANALYSIS, AND DESIGN OPTIMIZATION
K.K. Choi, V. Ogarevic, J. Tang, and Y.H. ParkCenter for Computer-Aided Design
College of EngineeringThe University of Iowa
Iowa City, IA 52242
Center for Computer Aided Design
Automotive Research Centerarc
CONTENTS OF THE PROCESS
l Create a Pro/E CAD Model of a Typical Passenger VehicleSystem and Automatically Translate It Into DADSDynamics Model
l Perform Dynamics Simulation of the Car Model Over aTypical Road Profile
l Create Parameterized CAD Model and FE Models of theFront Right Lower Control Arm
l Perform Fatigue Life Analysis of the Lower Control Arm
l Perform CAD-Based Fatigue Design Sensitivity Analysisand Optimization of the Lower Control Arm
l Reliability-Based Analysis and Design Optimization
Center for Computer Aided Design
Automotive Research Centerarc
Pro/E MODEL OF THE VEHICLE SYSTEM
26 Bodies Model
Center for Computer Aided Design
Automotive Research Centerarc
DADS MODEL OF THE VEHICLE SYSTEM
l Total of 22 Rigid Bodies
l Simulation Parameters:n 7 seconds straight line run
n RMS2 road profile: 0.316in. average peak to valleyheight
n Speed 10 m/sec
Center for Computer Aided Design
Automotive Research Centerarc
FRONT RIGHT SUSPENSION
X
FR_Lower Control Arm
Center for Computer Aided Design
Automotive Research Centerarc
Pro/E MODEL OF THE LOWERCONTROL ARM
Center for Computer Aided Design
Automotive Research Centerarc
JOINT REACTION FORCE HISTORIES(X-Direction at Three Joints)
Center for Computer Aided Design
Automotive Research Centerarc
FE MODEL OF THE LOWERCONTROL ARM
l Total Number of Elements: 297
l Element Type: ANSYS 20-Node Solid
l Total Number of Nodes: 1977
l Total Number of DoF: 5931
l Mesh Generator: MSC/PATRAN
Center for Computer Aided Design
Automotive Research Centerarc
FATIGUE LIFE PREDICTIONAPPROACH
l Obtain and Convert Joint Reaction Forces and InertialForces From Rigid or Flexible Multibody DynamicsSimulation in the Format Readable by DRAW
l Create FE Models That Are Consistent with the CADModel of the Structural Component
l Superimpose Stress Time Histories for All Surface Nodesof the FE Model Using Hybrid Method
l Perform Preliminary Analysis To Identify Critical Regions
l Perform Refined Analysis for Higher Fidelity Fatigue LifePredictions
Center for Computer Aided Design
Automotive Research Centerarc
COMPUTATIONAL FLOW CHART
Pro/EFEA ToolANSYS &NASTRAN
DynamicAnalysisDADS
CADModel(LCA)
GeometryPATRAN orHyperMesh
FE Model
FrameInformation
DADSOutput File
InterfaceDADS_READER
DynamicInformation
Load VectorCalculation Tool
DynamicParameters
Quasi StaticLoad Vectors
StressCoefficients
SuperpositionTool
Dynamic StressTime History
PreliminaryAnalysis Tool
RefinedAnalysis Tool
CriticalRegion
Crack Initiation Life
VehicleSystem
DRAW
Center for Computer Aided Design
Automotive Research Centerarc
STRESS HISTORY AT CRITICAL NODE(Three Principal Stresses)
Center for Computer Aided Design
Automotive Research Centerarc
ALGORITHM FOR FATIGUE LIFEPREDICTIONS IN DRAW
l Compute Stress/strain and Damage Parameter History
l Edit and Rainflow Count Damage Parameter History
l Identify Surface Critical Region Using PreliminaryLife Analysis with von Mises Strain Approach
l Estimate Elastic-plastic Strain at Critical Region
l Refine Life Predictions at Critical Region Using vonMises Strain Approach or More Advanced CriticalPlane Approaches
Center for Computer Aided Design
Automotive Research Centerarc
ESTIMATION OF ELASTIC-PLASTICSTRAINS
l Uniaxial Case:n Neuber’s Rule and Remberg-Osgood Equation
l Multiaxial Case:n Equivalent strain energy density approach
n Assumed elastic-plastic loading paths
n Currently linear kinematic hardening plasticity model(Mroz Model) is being implemented
Center for Computer Aided Design
Automotive Research Centerarc
LIFE PREDICTION METHODS
l Equivalent Strain Methods:n Von Mises equivalent strain approach with Smith-
Watson-Topper theory
n ASME Boiler and Pressure Vessel Code approach
l Critical Plane Methods:n Tensile strain based critical plane approach
(Fatemi-Socie)
n Shear strain based critical plane approach(Fatemi-Kurath)
Center for Computer Aided Design
Automotive Research Centerarc
FATIGUE CRACK INITIATION LIFECONTOUR
(Preliminary Analysis with von Mises Equivalent-Strain Approach)
Center for Computer Aided Design
Automotive Research Centerarc
CRITICAL REGION IDENTIFICATIONPROCEDURE
l User Selected Points
l Preliminary FatigueAnalysisn Calculate linear elastic von
Mises strain
n Calculate fatigue crackinitiation life for all surfacenodes
n Select critical nodes withminimum life
n The procedure is automatedin DRAW
LIST OF CRITICAL NODES
Center for Computer Aided Design
Automotive Research Centerarc
REFINED FATIGUE ANALYSIS AT THECRITICAL NODES(Equivalent Strain Method)
NodeNo.
560
583
590
PreliminaryAnalysis
Cycles Years
Refined Analysis(with Neuber)
Cycles Years
Refined Analysis(with EP)
Cycles Years
2.8901E8
3.2312E8
1.217E10
2.8295E8
3.1671E8
2.7053E8
2.2432E8
3.5239E8
3.9165E8
64 62 50
78
87
70
60
72
2700
Center for Computer Aided Design
Automotive Research Centerarc
CAD-BASED SHAPE OPTIMIZATIONAPPROACH
l Implement CAD-based Shape Design ParameterizationCapability within Pro/E Environment
l Use HyperMesh or PATRAN for Mesh Generation,ANSYS or NASTRAN for FEA, and DRAW for FatigueLife Prediction
l Develop a Design Velocity Field Computation MethodBased on Pro/E Shape Design Parameter
l Hybrid Method Is Used for Sensitivity Computationn Continuum DSA for Sensitivity of the Dynamic Stresses
n Finite Difference for Sensitivity of the Fatigue Life
l DOT Is Used for CAD-based Shape Design Optimization
Center for Computer Aided Design
Automotive Research Centerarc
COMPUTATIONAL FLOW CHART
Pro/ENGINEER
DesignParameterization
Velocity FiledComputation
Pro/EEnvironment
Mesh GeneratorHyperMesh or PATRAN
DRAW
DSA
DOT
DesignUpdate
DesignOptimization
Trade-offDetermination
What-ifStudy
SensitivityDisplay
CADModeler
DesignParameterization
Velocity FieldComputation
Mesh Generator
Life Prediction
DSO
4-StepDesign Process
DesignOptimization
SensitivityAnalysis
Center for Computer Aided Design
Automotive Research Centerarc
CAD-BASED DESIGN PARAMETERIZATION
l CAD Model Must BeWell-Constructed :• Able to regenerate
perturbed models inlarge design space
• Maintain topologywhen regenerating
• Exported geometrymust support meshgeneration byHyperMesh orPATRAN
Center for Computer Aided Design
Automotive Research Centerarc
DESIGN PARAMETERIZATION
l Design Parameters Are Chosen From Pro/E FeatureDimensions Such as Length, Radii, General Surface, etc.
l Design Parameters Selection by Pointing and Clicking atPro/E Display
l Identify FE Nodes on CAD Surfacesn PATRAN generates a file including FE surface node information
n This step is automated if meshes are generated by Pro/E
l Boundary Design Velocity Fields Are Computed UsingFinite Difference Method Based on CAD Regeneration
l Domain Velocity Fields (Velocity of Interior Nodes) AreComputed Using Boundary Displacement Method