LS-DYNA General Update - Oasys ??LS-DYNA ENVIRONMENT Outline of talk LS-DYNA LS-DYNA...

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Transcript of LS-DYNA General Update - Oasys ??LS-DYNA ENVIRONMENT Outline of talk LS-DYNA LS-DYNA...

  • LS-DYNA ENVIRONMENT

    LS-DYNA General Update

    Oasys LS-DYNA Users Meeting

    India

    Pune & Bangalore

    April 2012

  • LS-DYNA ENVIRONMENT

    LS-DYNA Outline of talk

    LS-DYNA

    Versions

    Two Things first

    MPP Parallel, Hybrid and Results

    *CASE

    LS-Dyna version 971 R5/R6 Updates

    Frequency Domain

    Discrete Element Method

    Isogeometric Elements

    SPH Updates

    Implicit Updates

    Misc Updates

    LS-Dyna Version 980

    EM Solver

    ICFD Solver

    CESE Solver

    FE-MODELS

    Conferences

  • LS-DYNA ENVIRONMENT

    LS-DYNA Versions of LS-DYNA

    LS-Dyna 971 Release 2

    LS 971 7600.1224

    Release 3

    LS 971 R3.2.1

    Release 4

    LS 971 R 4.2.1

    Release 5

    LS 971 R5

    LS 971 R5.1

    LS 971 R5.1.1

    Release 6

    LS 971 R6.0.0

    Latest release (January 2012)

    Updated pdf version of manuals.

    Volume 1 - Main Keywords

    Volume 2 Materials

    LS 971 R6.1 (Later 2012)

    Development version

  • LS-DYNA ENVIRONMENT

    LS-DYNA Versions of LS-DYNA

    LS-Dyna 980 Multiphysics version

    Three new solvers

    Electromagnetics (EM)

    Compressible fluids solver (CESE)

    Incompressible fluids solver (ICFD)

    Double precision only for new solvers

    Manual in three volumes

    Volume 1 - Main Keywords

    Volume 2 Materials

    Volume 3 Multiphysics

  • LS-DYNA ENVIRONMENT

    LS-DYNA LSTCs One Code Strategy

    Combine the multi-physics capabilities into one scalable code for solving

    highly nonlinear transient problems to enable the solution of coupled multi-

    physics and multi-stage problems

    Explicit/Implicit

    Heat Transfer

    Mesh Free EFG,SPH,Airbag Particle

    User Interface Elements, Materials, Loads

    Acoustics Frequency

    Response, Modal Methods

    Discrete Element Method

    Incompressible Fluids

    CESE Compressible Fluid

    Solver

    Electromagnetism

    980

    980

    980

  • LS-DYNA ENVIRONMENT

    TWO THINGS FIRST

  • LS-DYNA ENVIRONMENT

    LS-DYNA MPP, Hybrid and Results

    There is a consistency option (ncpu=-N) in LS-DYNA SMP version. Many customers used to run their jobs with the option in SMP era, even though there is about 10-15% performance penalty with the option.

    This option has also been implemented into LS-DYNA Hybrid version. So customers can use the option for getting consistent numerical result. However, there is a condition here:

    First released in R5 and further developed in R6, it runs SMP within each processor and MPP between the processors.

    If the number of SMP threads is increased, results remain identical.

    To run the Hybrid option both SMP and MPP variables are set.

    mpirun np 12 mpp971hyb i=input memory=xm memory2=xm ncpu=-4

    12 MPI threads

    4 way SMP within each MPI thread

    48 cores used in total

    You need to fix the number of MPI processes.

    HYBRID LS-DYNA

  • LS-DYNA ENVIRONMENT

    LS-DYNA

    0

    5

    10

    15

    20

    25

    30

    35

    40

    1 2 4 8 16 32 64 128

    sp

    eed

    up

    number of nodes

    pure MPI

    hybrid

    Note: There are 12 cores in each node

    196 cores

    Car2Car model

    1.5 million shells

    12 cores per node system

    LS-DYNA R4.2.1 Hybrid Intel MPI

    MPP, Hybrid and Results

  • LS-DYNA ENVIRONMENT

    LS-DYNA

    Consistent results are obtained with fix decomposition and changing number of SMP threads

    Neon Model 8, 16 and 24 cores

    MPP, Hybrid and Results

  • LS-DYNA ENVIRONMENT

    LS-DYNA

    Different results Which is correct ?

    MPP, Hybrid and Results

  • LS-DYNA ENVIRONMENT

    LS-DYNA

    Stricter modelling practice reduces spread in results. - What is good practice?

    MPP, Hybrid and Results

  • LS-DYNA ENVIRONMENT

    LS-DYNA

    Best Practice for Explicit Crash Simulations.

    (Of course there will be exceptions to these guidelines.)

    Shell Elements

    Element formulation 2 with stiffness based hourglass control type 4 (and QH = 0.05)

    Element formulation 16 with hourglass control type 8

    5 through thickness integration points

    *CONTROL_SHELL

    Shell thickness change ISTUPID = 0 (off), or 4 (on but elastic strains are neglected)

    Full sorting of degenerate shells to C0 triangles (ESORT=1)

    Add warping stiffness (BWC=1)

    Use full projection for adding warping stiffness (PROJ=1)

    Delete highly distorted elements (NFAIL1 & NFAIL4 = 1)

    *CONTROL_BULK_VISCOSITY

    Set TYPE to -1 or -2 to include shell elements. Essential for type 16 shells

    *CONTROL_ACCURACY

    Objective stress update on OSU=1

    Invariant node numbering on for shell , thick shell and solids (INN=4)

    MPP, Hybrid and Results

  • LS-DYNA ENVIRONMENT

    LS-DYNA

    Solid Elements

    Element formulation 1 with stiffness or viscous hourglass control (sitting on fence here)

    Element formulation 13 for tetrahedron elements (Metals/Rubbers/foams)

    Element formulation 10 for tetrahedron elements (Can be used for foams)

    Element formulation 1 with hourglass 6 for spotwelds (mat 100)

    CONTROL_SOLID

    Automatic sorting of degenerate elements ESORT=1

    (ESORT=2 in 971R6 sorts pentahedron to new formulation 115 under review)

    Materials

    Make sure all curves used to define stress-strain relationships are smooth.

    Where a table of curves are defined try to aim for reasonable spacing between curves and make sure curves do not cross.

    Use visco-plasticity (VP=1) where available for strain rates

    MPP, Hybrid and Results

  • LS-DYNA ENVIRONMENT

    LS-DYNA

    Contacts

    Eliminate crossed edges

    Avoid initial penetrations (if possible)

    Use IGNORE=2 (or 1 if information is not required) to ignore any initial penetrations

    Use SOFT=1 for contacts with large differences in stiffness. (usually no harm to use this as the default)

    MPP, Hybrid and Results

  • LS-DYNA ENVIRONMENT

    LS-DYNA *CASE

    *CASE Multiple models defined within a single input deck

    Models run consecutively by LS-DYNA

    Recommended to keep differences simple

    Can be useful to define multiple static load cases in a linear implicit analysis

    *CASE

    $..ID.....

    100 Case ID

    $ Command line arguments

    memory=100m

    $ Active IDs for this case

    $ ID1 ID2 ID3

    3 5 9

    In the above CASE 100 is made up from sub-case definitions 3, 5 and 9

  • LS-DYNA ENVIRONMENT

    LS-DYNA *CASE

    Sub-case definitions are defined by either nesting keywords between

    *CASE_BEGIN and *CASE_END statements .e.g. for sub-case 5

    *CASE_BEGIN_5 *LOAD_NODE_POINT

    $:nid/nsid dof lcid sf cid

    93 3 1 -0.5 0

    *CASE_END_5

    or

    By using CID=xx after the keyword .e.g. for sub-case 5

    *LOAD_NODE_POINT CID=5 $:nid/nsid dof lcid sf cid

    93 3 1 -0.5 0

  • LS-DYNA ENVIRONMENT

    LS-DYNA *CASE

    Notes

    *CASE_BEGIN and *CASE_END statments can be nested and overlap.

    Any keyword not defined as belonging to a sub-case is active for all cases.

    Most pre-processors do not yet understand the concept of *CASE

    To be added to Oasys Primer version 11

    It is easy to get confused between CASE and sub-case IDs .

    To run add CASE after i=file name on input LS-DYNA execution line

    mpirun np xx mpp971 i=input.key CASE

    ls971 i=input.key CASE

    Output files are called casexxx.d3plot, casexxx.binout etc.

  • LS-DYNA ENVIRONMENT

    LS-DYNA *CASE example

    EXAMPLE

    Simple shell cantilever

    Five Cases

    Case 101 - sub case 1 vertical load up

    Case 102 - sub-case 2 vertical load down

    Case 103 - sub-case 3 horizontal load left

    Case 104 - sub-case 4 horizontal load right

    Case 111 - sub-cases 111 + 4 + 1

    Sub case added to allow correct title to be defined.

  • LS-DYNA ENVIRONMENT

    LS-DYNA *CASE example *KEYWORD

    $

    *CASE

    101

    MEMORY=20M

    1

    *CASE

    102

    MEMORY=20M

    2

    *CASE

    103

    MEMORY=20M

    3

    *CASE

    104

    MEMORY=20M

    4

    *CASE

    111

    111 4 1

    *TITLE CID=1

    Implicit Example - Vertical Load 1 (Down)

    *TITLE CID=2

    Implicit Example - Vertical Load 2 (up)

    *TITLE CID=3

    Implicit Example - Horizontal Load 3 (Left)

    *TITLE CID=4

    Implicit Example - Horizontal Load 4 (Right)

    *TITLE CID=111

    Implicit Example - Title for CID 111

    $

    $

  • LS-DYNA ENVIRONMENT

    LS-DYNA *CASE example $

    $ ==========

    $ LOAD cards

    $ ==========

    $

    *CASE_BEGIN_1

    *LOAD_NODE_POINT

    $:nid/nsid dof lcid sf cid

    93 3 1 -0.5 0

    *CASE_END_1

    $

    *CASE_BEGIN_2