Single model Multi Attribute Analysis and Optimization · PDF file 2018-10-18 ·...

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Transcript of Single model Multi Attribute Analysis and Optimization · PDF file 2018-10-18 ·...

  • Single model Multi Attribute Analysis and Optimization

    Amar Ourchane, Ford Motor Company

    Abhilash Patel, Altair

    27 September 2018 1

  • Goal

    “Establish a single model to assess Stiffness, Strength and Fatigue on an

    automotive rear subframe model for both parent metal and weldments.”

    2

  • Benefits of single model approach

    1. Drives the use of common model practice for modeling efficiencies and

    elimination of modeling inconsistencies due to multiple model build and

    analysis processes for Stiffness, Strength and Fatigue load cases (i.e. model

    counts, non-uniform material definitions, ID management, etc)

    2. Offers a better way to efficiently perform and assess design iterations and

    improvements, and enables possibilities for Design Exploration with direct

    optimization ready format

    3. Common model for Strength and Fatigue assessment, enables simpler

    automation and ensures efficient attributes tracking across CAE groups for

    quicker design progression 3

  • Traditional process :

    Optimization

    Cost

    Efficient

    NVH & Global Stiffness –

    Nastran AMLS

    OptiStruct AMLS/AMSES

    Strength – Abaqus

    Fatigue Durability : Parent and welds– internal Solver

    4

  • objective

    Optimization Ready

    Single CAE model

    NVH & Global Stiffness

    Strength

    Fatigue Durability

    Altair OptiStruct™

    5

  • Process flexibility

    Stiffness

    ❑Solver A/B

    ✓ OptiStruct

    Strength ✓ OptiStruct

    Fatigue ✓ OptiStruct

    Pre Processing

    ▪ Fatigue set up

    Solver

    ▪ DAC,RPC,RSP file channel handling

    within solver

    Post Processing:

    ▪ Dynamic Stiffness population

    Optimization Set up:

    ▪ Design Variable and linking

    ▪ Response and Constraint set up

    Automation for Single Model and Optimization

    6

  • Process flexibility

    Concept and Fine tuning Optimization

    Optimization Ready

    Stiffness

    ❑Solver A/B model

    ✓ OptiStruct model

    Strength

    ✓ OptiStruct model

    Fatigue

    ✓ OptiStruct model

    +

    +

    7

  • Loadcase Review

    8

  • SCOPE

    Durability Model (Abaqus)

    Sources of Nonlinearity:

    • Nonlinear Material

    • Permanent Set due to Load/Unload

    Response:

    • Displacement & Plastic Strain (O/P)

    Fatigue Subcases (Internal Solvers)

    • Parent metal Fatigue

    • Seam weld Fatigue

    NVH Model (Nastran)

    • Modal Frequency Response

    Response:

    • Dynamic Stiffness (42 subcases) 9

  • Stiffness

    10

  • NVH loadcase

    ▪ Dynamic stiffness results at 2 Hz (Nastran run with CQUAD4 vs modern

    CQUAD4 in OS)

    ▪ Less than 2 % variation

    Showing only above 1% variation 11

  • Automated Multi-level Sub-structuring

    ▪Approximate eigen value solvers can be used instead of Lanczos to reduce the

    cost of frequency response and eigenvalue analysis for large finite element

    models

    ▪AMSES is a multi-threaded application and can use any number of processors.

    ▪FASTFRS and FASTFR are available within OptiStruct

    ▪ AMSES, Automated Multi-level Sub-structuring Eigen Value Solver is built into

    OptiStruct and it kicks in automatically when EIGRA is used instead of EIGRL.

    12

  • Strength

    13

  • Strength loadcase – Permanent Set

    14

  • PLASTIC STRAINS

    ▪ Loading / Un-loading : Permanent Set problem solved in Abaqus was

    converted to OptiStruct

    • ABAQUSOPTISTRUCT Plastic Strain Results

    15

  • Strength loadcase

    ▪ Loading / Un-loading : Permanent Set problem solved in Solver A was

    converted to OptiStruct

    Loading ABAQUSOPTISTRUCT Displacement Results

    16

  • Durability loadcase

    ▪ Loading / Un-loading : Permanent Set problem solved in Solver A was

    converted to OptiStruct

    Unloading Displacement Results

    ABAQUSOPTISTRUCT

    17

  • Conversion process

    ▪ OptiStruct converters within HyperMesh used

    ▪ 99% conversion rate of existing load cases

    ▪ OptiStruct check runs and elaborate error/warning messages help

    identify and fix any formatting concerns

    ▪ No need for null skin mesh. OptiStruct has direct output requests for membrane of solid

    ▪ Modify negative or zero slope terms on material stress strain curve

    18

  • Other strength simulations requirements

    Nonlinear MaterialNonlinear Contact Small and Large Displacement Analysis

    Large Scale Computing & Parallelization

    20 40 80 160 320

    Cores

    19

  • Fatigue

    20

  • Fatigue loadcase

    ▪ Direct support of RSP/DAC files in OptiStruct enable ease in set up

    ▪ Solver pick up channels directly from rsp files

    ▪ Both parent metal and seam weld fatigue run in a single model set up

    ▪ Parent metal : Strain-Life (E-N) Approach

    ▪ SWT Model

    ▪ Seam weld : (not addressed in this study)

    ▪ VOLVO method 21

  • InternalSolver_____OptiStruct Fatigue

    22

  • InternalSolver_____OptiStruct Fatigue

    23

  • InternalSolver_____OptiStruct Fatigue

    24

  • InternalSolver_____OptiStruct Fatigue

    25

  • InternalSolver_____OptiStruct Fatigue

    26

  • InternalSolver_____OptiStruct Fatigue

    27

  • Simulation Run times

    Single Attribute model run times Single

    model

    Multi

    Attribute Durability NVH

    Parent

    metal

    Seam Weld

    Fatigue

    SMP 4 cpus

    (available @ Ford) 00:13:14 00:03:50 00:28:38 00:34:00 01:43:11

    DDM 48 cpus

    (available @ Ford) 00:05:41 00:01:00 00:03:36 00:05:00 00:11:00

    29

  • Permanent Set @ LH Hardpoints

    ▪ Analysis can be done using small and large displacement theory

    ▪ Optimization process assumes only small displacement theory for now

    ▪ Results between both large and small are comparable

    30

  • Neuber corrected stress / strain responses

    www.efatigue.com

    Neuber correction responses are

    used in both linear and nonlinear

    static (small displacement)

    optimization subcases

    31

  • GAUGE optimization

    Gauge Design Variables for parent metal and weldments

    Design variable links with weldment thickness as a function of parent metal gauge

    Life / Damage as a response

    5 Hard points Permanent set – 2 mm

    Neuber Corrected Stress/Strain response – 2%

    42 Dynamic Stiffness constraints 5 % degradation

    Minimize Mass

    32

  • Iteration History

    • Design freedom provided – 0.65 to 4.5 mm

    • Initial starting point : 4.5 mm – Very liberal

    Objective:Mass

    Dynamic Stiffness

    (KN/mm)

    33

  • Other possible Optimization opportunities

    1. Topology(Blow holes) and Topography(Add beads) on parent metal to

    improve stiffness.

    2. 2D Topology on seam weld PSHELLS – Objective / Constraints = Mass /

    weld Life.

    3. Freeshape parent metal – Objective / Constraints = Mass /Life/ Neuber

    Stress/ disp

    34

  • October 10, 2018 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved.©

    FOR MORE QUESTIONS ON THE PROCESS

    FLOW AND SET UP

    WORKSHOP/SEMINAR ROOMS

    35