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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 LSTC’s 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


LS-DYNA ENVIRONMENT

LS-DYNA

Different results – Which is correct ?


LS-DYNA ENVIRONMENT

LS-DYNA

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


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)


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


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)


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 ID’s 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


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 ID’s .

• 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


*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


$

$ ==========

$ LOAD cards

$ ==========

$

*CASE_BEGIN_1

*LOAD_NODE_POINT


93 3 1 -0.5 0

*CASE_END_1

$

*CASE_BEGIN_2

*LOAD_NODE_POINT


93 3 1 +0.5 0

*CASE_END_2

*CASE_BEGIN_3

*LOAD_NODE_POINT


93 2 1 -500.0 0

*CASE_END_3

$

*CASE_BEGIN_4

*LOAD_NODE_POINT


93 2 1 500.0 0

*CASE_END_4

$

$

LS-DYNA ENVIRONMENT


LS-DYNA ENVIRONMENT

LS971 R5/R6 UPDATES

LS-DYNA ENVIRONMENT

Frequency Domain Analysis

LS-DYNA ENVIRONMENT

LS-DYNA *FREQUENCY_DOMAIN

*FREQUENCY_DOMAIN keywords

• FREQUENCY_DOMAIN_FRF

• FREQUENCY_DOMAIN_SSD

• Steady state dynamics with harmonic loading

• FREQUENCY_DOMAIN_RANDOM_VIBRATION_{OPTION}

• Called as “vibro acoustic solver” previously

• Based on Boeing’s in-house code “N-FEARA”

• Random fatigue as an option

• FREQUENCY_DOMAIN_ACOUSTIC_BEM_{OPTION}

• BEM / Rayleigh method / Kirchhoff method

• Irregular frequency problem for exterior

• Good for interior / exterior problems

• FREQUENCY_DOMAIN_ACOUSTIC_FEM

• Available elements: hexahedron, tetrahedron

• Good for interior problems

• FREQUENCY_DOMAIN_RESPONSE_SPECTRUM

LS-DYNA ENVIRONMENT


Areas of application • NVH analysis

• Interior noise

• Vibration

• BSR (Buzz, Squeak and Rattle)

• Engine noise

• Structural vibration

• FRF

• SSD

• Civil and Earthquake engineering

• Response spectrum

• Acoustic design of concert halls

• Off-shore engineering, wind turbine etc

• Random vibration

• Random fatigue

LS-DYNA ENVIRONMENT


New binary database files • *DATABASE_FREQUENCY_BINARY_OPTION

• Available options

• D3ACS, D3FTG, D3PSD, D3RMS, D3SPCM and D3SSD

Card 1 1 2 3 4 5 6 7 8

Variable BINARY

Type I

Default 1

Card 2 1 2 3 4 5 6 7 8

Variable FMIN FMAX NFREQ FSPACE LCFREQ

Type F F I I I

Default 0.0 0.0 0 0 0

Mode n Mode n+1 Mode n+2

FMAX FMIN

(Biased spacing)

(Logarithmic spacing)

(Linear spacing)

LS-DYNA ENVIRONMENT


BEM Acoustics • Keyword

• *FREQUENCY_DOMAIN_ACOUSTIC_BEM

• A wide choice of methods

• Rayleigh method

• Kirchhoff method

• Indirect variational BEM

• Collocation BEM

• Dual BEM with Burton-Miller formulation

• Boundary conditions given by

• Direct load curve input

• Time domain dynamic analysis followed by FFT conversion

• Frequency domain steady state dynamic analysis

• Acoustic panel contribution analysis

LS-DYNA ENVIRONMENT


BEM Acoustics – Ex. Radiated noise by a car

f = 21 Hz

f = 101 Hz

• By coupling with Steady State Dynamics or transient analysis, BEM acoustics can be used to predict radiated noise by a vehicle.

• The model shown here is a simplified auto model, which is fixed to a shaker table through the four wheels.

• Harmonic nodal force excitation is applied at the top of the compartment.

• The radiated noise around the vehicle at two frequencies 21 Hz and 101 Hz can be computed.

• The two figures show the distribution of the radiated noise level (dB) for the two frequencies.

LS-DYNA ENVIRONMENT

LS-DYNA

Observation point

*FREQUENCY_DOMAIN

FEM Acoustics • *Keyword

• *FREQUENCY_DOMAIN_ACOUSTIC_FEM

• Solve interior acoustic problem

• Tetrahedron and Hexahedron elements available

• Very fast since only 1 unknown at each node

Simplified compartment example

• Example shows cross-validation between FEM and BEM of LS-DYNA and with NASTRAN.

LS-DYNA ENVIRONMENT

Discrete Element Method

LS-DYNA ENVIRONMENT

LS-DYNA *Mat_rigid_discrete (mat 220)

• A single rigid material is defined which contains multiple disjoint pieces. Input is simple and unchanged, since all disjoint rigid pieces are identified automatically during initialization.

• Rigid body mechanics is used to update each disjoint piece of any part ID which references this material type.

• Can be used to model granular material where the grains interact through an automatic single surface contact definition.

• Eliminates the need to define a unique rigid body for each particle when modelling a large number of particles

• Reduction in memory and wall clock time over separate rigid bodies

• Each rigid piece can contain an arbitrary number of solid elements that are arranged in an arbitrary shape.

LS-DYNA ENVIRONMENT

LS-DYNA *Mat_rigid_discrete (mat 220)

LS-DYNA ENVIRONMENT

LS-DYNA *Discrete Method

Discrete Element Method • Discrete method is now extended to spherical

shapes which eliminates the need for an FE mesh and the need to update multiple nodes per particle, which is hugely expensive

• For cases where the particles can be modelled with geometric shapes, e.g. spheres, cylinders, ellipsoids, meshing of particles is not needed for solving contact and analytical contact can be used, similar to *Contact_entity

• Spherical particles with arbitrary radii have been implemented for

• Elastic impact

• Inelastic impact

• Combination of elastic and inelastic impacts

• Speed is considerably faster than with arbitrarily shaped particles and general single surface contact

LS-DYNA ENVIRONMENT

LS-DYNA *Discrete Method

Discrete Element Method • Assumption is that the material being modelled

consists of discrete particles e.g.

• liquids

• bulk materials in silos

• Granular materials (sand)

• Powders

• Industries include

• Civil Engineering

• Agriculture and food handling

• Oil and gas

• Mining

• Powder metallurgy

LS-DYNA ENVIRONMENT

LS-DYNA *Element_discrete_sphere

New keywords for Discrete Sphere method • *CONTROL_DISCRETE_ELEMENT

• Define global control parameters, including damping and friction

• Can also define if the particles are wet or dry. If wet then the capillary force between particles is included (971 – Development version).

• *ELEMENT_DISCRETE_SPHERE

• Define pid, mass, inertia and radii of the sphere

• *DEFINE_DE_ACTIVE_REGION

• Define a region of interest.

• Outside of this region any discrete elements are removed from collision and contact calculations.

LS-DYNA ENVIRONMENT


Porosity

MAT_20 0.409

MAT_220 0.409

Element Discrete 0.399

1488913384

1207

Analysis Time (secs)

LS-DYNA ENVIRONMENT


Dry vs. Wet Spheres

Dry

Wet

Effects of viscosity on the mechanical response of a liquid bridge is considered.

LS-DYNA ENVIRONMENT


LS-DYNA ENVIRONMENT

Isogeometric Analysis

LS-DYNA ENVIRONMENT

LS-DYNA Isogeometric Analysis

ISOGEOMETRIC-Analysis

• NURBS (Non-Uniform Rational B-Spline) based finite elements

• Research since 2003

• Many promising features (CAD-FEA, accuracy)

• First implementations for production applications…

• 2D-NURBS for shell analysis

• Boundary conditions (contact) with interpolation nodes/elements

LS-DYNA ENVIRONMENT


NURBS-Patch and the definition of elements

LS-DYNA ENVIRONMENT


Keywords –

• *ELEMENT_SHELL_NURBS_PATCH

• definition of NURBS-surfaces

• Number of control points in local r (and s) direction

• Order of polynomial in local r (and s) direction

• Number of automatically created shell elements in r (and s) direction, used for

• Visualisation (post-processing)

• Boundary conditions

• Contact

• 4 different shell formulations with/without rotational degrees-of-freedom

• *SECTION_SHELL

• ELFORM = 201

• Define thickness

• Analysis capabilities

• explicit time integration

• Implicit time integration

• eigenvalue analysis

• geometric stiffness for buckling – under development

LS-DYNA ENVIRONMENT

LS-DYNA

x

y

z

*ELEMENT_SHELL_NURBS_PATCH

$---+-NPID----+--PID----+--NPR----+---PR----+--NPS----+---PS----+----7----+----8

11 12 4 2 5 2

$---+--WFL----+-FORM----+--INT----+-NISR----+-NISS----+IMASS----+----7----+----8

0 0 1 2 2 0

$knot-vector in r-direction

$rk-+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8

0.0 0.0 0.0 1.0 2.0 2.0 2.0

$sk-+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8

0.0 0.0 0.0 1.0 2.0 3.0 3.0 3.0

$net+---N1----+---N2----+---N3----+---N4----+---N5----+---N6----+---N7----+---N8

1 2 3 4

5 6 7 8

9 10 11 12

13 14 15 16

17 18 19 20

Control Points

Control Net r

s

20

3

4

1

2

5 6

9

7

8

10

11

12

13

14

15

16

17

18 19

Isogeometric Analysis

NPR, PR - #control pts & order (r-direction)

NSIR, #shell elements (r-direction)

LS-DYNA ENVIRONMENT


nisr=niss=2 nisr=niss=10

NURBS Surface Interpolation Nodes/Elements

LS-DYNA ENVIRONMENT


Isogeometric benchmark problem – LSTC • Study comparing

• Standard (non adaptive)

• Standard (adaptive)

• NURBS

LS-DYNA ENVIRONMENT


Standard and NURBS Analysis

• *MAT_TRANSVERSELY_ANISOTROPIC_ELASTIC_PLASTIC (*MAT_037)

• number of integration points through the thickness (nip=5)

• no thickness update (istupd=0)

• no mass scaling

• SMP, double precision, ncpu=4 (Dual Core AMD Opteron, 2.2 GHz)

Standard elements

• fully integrated (4-noded) shell-elements with assumed strain formulation (elform=16)

• Discretisation

• with adaptivity (mesh size: 4mm <-> 2mm <->1mm) as reference solution

• without adaptivity: mesh-sizes: 2mm; 4mm; 8mm

2D-NURBS elements

• FORM=2 (rotation free formulation)

• INT=0 (reduced integration)

• Polynomial

• p2 (quadratic) p3 (cubic)

• p4 (quartic) p5 (quintic)

• Discretisation

• mesh-sizes: 4mm; 8mm; 16mm

• number of interpolation elements/ NURBS-elements: NISR=PR; NISS=PS

LS-DYNA ENVIRONMENT


Isogeometric benchmark problem – LSTC • Reference solution – Adaptivity

4mm 2mm 1mm

LS-DYNA ENVIRONMENT


Good correlation between traditional adaptivity based stamping and NURBS-P2-4mm

Standard-Adaptivity NURBS-P2-4mm

LS-DYNA ENVIRONMENT


Summary and further developments • NURBS based elements are stable

• Code optimization necessary to make it faster but already competitive.

• Perform a lot more studies in different fields

• Further implementation

• (selective) mass scaling

• thickness update of shells

• use NURBS for contact (instead of interpolation elements)

• make pre- and post-processing more user-friendly

• introduce 3D NURBS elements

• ........much more

LS-DYNA ENVIRONMENT

SPH Updates

LS-DYNA ENVIRONMENT

LS-DYNA SPH

*DEFINE_ADAPTIVE_SOLID_TO_SPH • Define solid parts whose elements will be transformed to SPH partricles (elements) when

the solid element fails.

• The created SPH elements inherit all the properties of the failed solid element:

• Mass

• Kinematic variables

• Constitutive properties.

• Number of SPH particles created per element is user controlled E.g. For hexahedral elements this can be 1, 8 or 27 particles.

• Newly generated particles can be either:

• Not coupled to adjacent solids (debris simulation)

• Coupled to adjacent solids

NQ = 2, Hex element is adapted to 8 SPH particles.

NQ = 2, Tet element is adapted to 4 SPH particles.

LS-DYNA ENVIRONMENT

LS-DYNA SPH

Hybrid elements (SPH/SOLID) • Used as transit layers between SPH elements and Solid elements.

• Solid elements constrain SPH nodal locations.

• SPH elements provide "penalty force“ against solid nodal motion.

• *DEFINE_ ADAPTIVE_SOLID_TO_SPH, ICPL=1 creates hybrid elements as transit layers between

SPH elements and Solid elements

SPH elements Solid elements Hybrid elements

LS-DYNA ENVIRONMENT

LS-DYNA SPH

*DEFINE_SPH_TO_SPH_COUPLING • Define a penalty based contact. This option is to be used for the node to node contacts

between SPH parts.

• Contact between two SPH particles from different parts is detected when the distance of two SPH particles is less than SRAD*(sum of smooth lengths from two particles)/2.0.

• SRAD – Scale factor defined on DEFINE_SPH_TO_SPH_COUPLING

LS-DYNA ENVIRONMENT

LS-DYNA SPH -

*DEFINE_ADAPTIVE_SOLID_TO_SPH - Taylor bar

LS-DYNA ENVIRONMENT

LS-DYNA SPH -

F

*DEFINE_ADAPTIVE_SOLID_TO_SPH - Sideways push

LS-DYNA ENVIRONMENT

LS-DYNA SPH -

*DEFINE_ADAPTIVE_SOLID_TO_SPH - Eroding impactor.

LS-DYNA ENVIRONMENT

LS-DYNA SPH – Thermal Coupling

SPH - Thermal Coupling • A new explicit thermal conduction solver is implemented for SPH analysis

• Following keywords are supported

• *INITIAL_TEMPERATURE_OPTION

• *BOUNDARY_TEMPERATURE_OPTION

• *BOUNDARY_FLUX_OPTION

• Thermal coupling with SPH is implemented

LS-DYNA ENVIRONMENT

LS-DYNA SPH - Thermal Coupling

vel

Conversion of mechanical work to heat

Tcwfworkeqheat ))((

LS-DYNA ENVIRONMENT

Implicit Updates

LS-DYNA ENVIRONMENT

LS-DYNA Implicit LS-DYNA

Implicit developments continue – • Main areas of development

• Convergence

• Speed of solution

• Memory used by solvers

• MPP improvements

• Use of GPUs

• Nvidia C2050 represents a factor of 8 faster computational engine than an 8 core processor.

• Hundreds of Single Instruction Multiple Data cores

• Faster memory.

LS-DYNA ENVIRONMENT


GPU Performance on LS-Dyna Implicit • AWE Benchmark 1 million nodes

• PC with a dual quad core Xeon 5560 processors and 2 Nvidia Tesla boards. The host has 96 Gbytes of memory while each GPU has 2 Gbytes of memory

No. of MPI

Ranks

Factor WCT

w/out GPU

Factor WCT

w/ GPU

Elapsed WCT

w/out GPU

Elapsed WCT

w/ GPU

1 10111 2885 25359 9163

2 9682 2251 23986 8387

LS-DYNA ENVIRONMENT


Linear Implicit with Adaptivity • Adaptive meshing allows stress concentrations to be automatically resolved in linear static

calculations.

• Implementation in LS-DYNA R6.

• If 4 levels of adaptive remeshing are specified, then 4 load steps are performed holding the load constant. Error norms are computed each step to determine which elements are refined.

• Super-convergent Patch Recovery, SPR, is now the default for error estimate

STEP 1

#nodes 706 #eles 625

STEP 2


STEP 3


STEP 4


LS-DYNA ENVIRONMENT

Misc Updates

LS-DYNA ENVIRONMENT

LS-DYNA *SET_xxxxx_INTERSECTION

*SET_xxxx_INTERSECTION • Define a set as the intersection, ∩, of a series of specified sets. The new set, SID, contains the

common elements of all named sets.

• Applies to:

• *SET_BEAM

• *SET_NODE

• *SET_SEGMENT

• *SET_SHELL

• *SET_SOLID

LS-DYNA ENVIRONMENT

LS-DYNA *DEFINE_TABLE_2D, *DEFINE_TABLE_3D

New keywords simplifying the definition of tables. • *DEFINE_TABLE_2D

• Unlike the *DEFINE_TABLE keyword, a curve ID is specified for each abscissa value defined in the table.

• The same curve ID can be referenced by multiple tables, and the curves may be defined anywhere in the input file.

• *DEFINE_TABLE_3D

• 3D table definitions are now available that follow the same approach

• A table ID is specified for each abscissa value defined for the 3D table

LS-DYNA ENVIRONMENT

LS-DYNA

*DEFINE_TABLE_3D

$ tbid

2000

$ temperature tbid

20. 100

500. 200

1000. 300

*DEFINE_TABLE_2D

$ tbid

100

$ strain_rate lcid

0.1 101

1.0 102

10.0 103

*DEFINE_CURVE

$ lcid

101

$ strain stress

0.0 162

1.0 446

For each temperature, we specify a table

For each strain rate, we specify a load curve of s vs e

*DEFINE_TABLE_2D, *DEFINE_TABLE_3D

LS-DYNA ENVIRONMENT

LS-DYNA *DEFINE_TABLE_2D, *DEFINE_TABLE_3D

Consider a thermal material model. For each temperature, T, we have a table of hardening curves of stress versus strain at 3 strain rates.

T=1000

0.0

0.1

0.4

1.0

0.1 98 190 244 268

1.0 109 212 273 300

10. 115 224 287 316

T=500

0.0

0.1

0.4

1.0

0.1 130 253 325 357

1.0 146 283 364 400

10. 153 298 383 421 T=20

0.0

0.1

0.4

1.0

0.1 s = 162 s = 316 s = 406 s = 446

1.0 182 354 455 500

10. 192 373 479 527

e

e

T=20, TID=100

s

T=1000, TID=300

T=500, TID=200

ee

ee

ee

LS-DYNA ENVIRONMENT

LS-DYNA Improvement to *SENSOR_DEFINE

SENSOR_DEFINE • SET option added to

• *SENSOR_DEFINE_NODE,

• *SENSOR_DEFINE_ELEMENT

• Positive set ID requires all elements in a set to meet the switch condition to change the switch status

• Negative set ID switch status will change if at least one of elements in the set meets the switch

condition

Example - changes the switch status if every node in node_set 200 has velocity larger than 120.

*SENSOR_DEFINE_NODE_SET

$ SNSID NODE1 NODE1 VID CRD CTYPE

100 200 VEL

*SENSOR_SWITCH

$ SWITID TYPE SENSID LOGIC VALUE

700 SENSOR 100 GT 120.

LS-DYNA ENVIRONMENT

LS-DYNA Improvement to *SENSOR_CONTROL

*SENSOR_CONTROL • A more flexible way to control material switch between rigid and deformable.

• TYPE=DEF2RIG

• Status set to “ON” triggers the switch and deformable material becomes rigid.

• Rigidized material can then return to deformable status when status becomes “OFF”.

• As many as 7 SWITs can be input, any of them will change the status triggered by its preceding

SWIT or the initial condition, INTSTT.

*SENSOR_CONTROL

$ CNTLID TYPE TYPEID TIMEOFF

100 DEF2RIG 10

$ INITSTT SWT1 SWT2 SWT3 SWT4 SWT5 SWT6 SWT7

ON SENSOR 100 GT 120.

LS-DYNA ENVIRONMENT

LS-DYNA *ELEMENT_BEAM_PULLEY

*ELEMENT_BEAM_PULLEY • New keyword to define pulley for beam elements.

• General framework for pulley mechanism: rope / cable / belt / chain runs over a wheel beam elements run over pulley node

• Adapted from slipring mechanism for belts

• Available for truss beam elements (*SECTION_BEAM, ELFORM=3)

• Available for *MAT_ELASTIC and *MAT_MUSCLE

LS-DYNA ENVIRONMENT

LS-DYNA *MAT_ADD_EROSION

*MAT_ADD_EROSION - New failure criteria added • EPSEFF – Effective in-plane strain for cohesive element

• LCFLD – Forming Limit Diagram curve for shell elements

• EPSTHIN – Thinning strain to failure for shell elements

• New GISSMO features added

• LCSDG – Failure as function of triaxiality and Lode parameter

• LCSRS – Failure as function of plastic strain rate

• SHRF, BIAXF – Reduction factors for regularization

LS-DYNA ENVIRONMENT

LS-DYNA *ELEMENT_SHELL_COMPOSITE

q i b + bi

THICKi, of MAT i

*ELEMENT_SHELL_COMPOSITE

• A way to define elements for a general composite shell part where the shells within the part can have an arbitrary number of layers

• The material ID, thickness, and material angle are specified for the thickness integration points for each shell in the part

• The number of composite layers and overall shell thickness can change from shell to shell

• The thickness of each shell is the summation of the integration point thicknesses. The total number of integration points is arbitrary

• Implementation works with all standard shell formulations

• Only one part ID is needed. In the past, a unique part ID was required for each different layup

• Now extended to thick shells *ELEMENT_TSHELL_COMPOSITE

LS-DYNA ENVIRONMENT

LS-DYNA *MAT_ADD_AIRBAG_POROSITY_LEAKAGE

*MAT_ADD_AIRBAG_POROSITY_LEAKAGE • Allows the modelling of porosity leakage through non-fabric material when such material is used as part

of control volume

• Can be applied to

• airbag_hybrid

• airbag_Wang_Nefske

• Application includes pyrotechnic device design, where non-fabric material is used to model a control volume and leakage through area-dependent leakage has to be considered.

Vent hole

Fabric-Independent

Porosity (Airbag) Fabric-Dependent Porosity(MAT34)

Porosity leakage from non-fabric

material

LS-DYNA ENVIRONMENT

LS-DYNA Airbags – Null shell problem

Performance issue using null shells to cover vent holes

• Problem

• Single layer to ensure the flatness around vents

• Those elements will stretch a lot from their original geometry

• Bucket sort region size will increase by L3 for correct searching

• Solution

• A new bucket sort algorithm is implemented in R6

vent hole

Time zone / cycle

New

Old

LS-DYNA ENVIRONMENT

LS-DYNA ALE Developments

ALE Recent developments • Modified *EOS_JWL to get correct cavitation effect

• Variable FSI friction based on relative interface velocity

• *ALE_REFINE

• Refine ALE hexahedral solid elements locally. Each element called parent is replaced

by 8 child elements with a volume equal to 1/8th the parent volume.

• If only the 1st card is defined, the refinement occurs during the initialization.

• The 2nd card defines a criterion CRITRF to automatically refine the elements during

the run.

• If the 3rd card is defined, the refinement can be removed if a criterion CRITRM is

reached: the child elements can be replaced by their parents

LS-DYNA ENVIRONMENT

LS-DYNA ALE Developments - *ALE_REFINE

ALE_REFINE Example • Every cycle dynamically refine ALE cells that:

• coupled to the structure

• mixed with air and water

• volume fractions > 0.0

LS-DYNA ENVIRONMENT

LS980

LS-DYNA ENVIRONMENT

LS-DYNA LS980 - Solvers

LS-Dyna – Version 980 • EM solver involves an eddy-current approximation to the electromagnetics equations and couples to

both the thermal and structural solvers.

• iCFD incompressible CFD solver handles low Mach number single and two-fluid flows; it also couples with both the structural and thermal solvers for FSI and conjugate heat transfer.

• CESE compressible CFD solver performs high-accuracy explicit space-time solutions to the Euler and Navier-Stokes equations, with coupling to a chemical reactions and a stochastic particle capability for sprays and other applications. It also solves for FSI coupling.

New keywords are documented in Volume 3

• *CESE

• *CHEMISTRY

• Used in conjunction with CESE solver

• *EM

• *ICFD

• *MESH

• Mesh creation. Only tetrahedral or triangular 2d elements can be generated

• *STOCHASTIC

• Used in conjunction with the CESE solver

LS-DYNA ENVIRONMENT

LS-DYNA LS980 – EM Solver

Different solvers in one model

Coupled mechanical/thermal/electromagnetic simulations

EMThermal

MechanicalEM

ttOften

tt

:

10

Mechanical

Explicit

(or Implicit)

Electromagnetism

Implicit

Thermal

Implicit

Thermal

Plastic work

Temperature

Joule Heating

Nodal Positions

Force

LS-DYNA ENVIRONMENT

LS-DYNA

coil

field shaper

shaft

tube

axial pressure plate

LS980 – EM Solver

Example – Electromagnetic forming of automotive power train component

LS-DYNA ENVIRONMENT


LS-DYNA ENVIRONMENT


Strain at the end of EM forming

Current Density Lorentz Force

Strain at the end of Join test

LS-DYNA ENVIRONMENT

LS-DYNA LS980 – ICFD Solver

Incompressible Fluids Solver • Finite Element Formulation for Navier-Stokes Equation

• Implicit CFD and FSI analysis strongly coupled to implicit and explicit solid mechanics

• Support for mesh movement and large deformations keeping the mesh body fitted at all times

• Error control and adaptivity

• Turbulence models

• RANS

• LES

• Free surface and multi-phase approximations

• Parallel processing

• High level mesh manipulation.

• Automatic volume meshing and run time re-meshing.

• Boundary Layer mesh

This solver is the first in LS-DYNA to make use of a new volume mesher that takes surface meshes bounding the fluid domain as input. In addition, during the time advancement of the incompressible flow, the solution is adaptively re-meshed as an automatic feature of the solver. Another important feature of the mesher is the ability to create boundary layer meshes. These anisotropic meshes become a crucial part of the model when shear stresses are to be calculated near fluid walls.

LS-DYNA ENVIRONMENT

LS-DYNA LS980 – ICFD Solver

Solver based mesher In complicated geometries meshing for CFD problems could be a time consuming process for any commercial software. In most cases the initial geometry has poor resolution.

1 Geometry

– External mesher 2 Mesh 3 Analysis

LS-DYNA

The solver can automatically reconstruct and re-mesh the surface geometry to build the volume mesh ready for analysis. At run time error estimators may be used to automatically adapt the mesh.

LS-DYNA ENVIRONMENT

LS-DYNA LS980 – ICFD Solver - FSI

ICFD Solver – FSI • Coupled to most solid models in LS-DYNA

• Strong coupling available for implicit mechanics

• More Robust but more expensive

• Weak coupling for explicit mechanics

• Less robust and less expensive.

• Suitable for simpler couplings such as aeroelasticity

Tip vertical displacement

Contours of fluid vorticity

LS-DYNA ENVIRONMENT

LS-DYNA LS980 – ICFD Solver - FSI

Tip vertical displacement

Streamlines Visualization • Green dots are the source for the streamlines. The recirculation areas on the flag are shown.

LS-DYNA ENVIRONMENT

LS-DYNA LS980 – ICFD Solver – Free Surface

Free Surface Simulation • The free surface is implemented using a Level Set.

• It allows the simulation of free surface flows using a single phase model.

• The Level Set allows large time steps with CFL=>1.

LS-DYNA ENVIRONMENT

LS-DYNA LS980 – ICFD Solver – Drag Prediction

Ahmed Body Problem - industry standard benchmark for drag prediction • Bluff body for validation of measurements and simulations in vehicle areodynamics

• Simple geometry

• Primary behaviour of vehicle aerodynamics retained

• Typical stream shapes

LS-DYNA ENVIRONMENT

LS-DYNA

12 degrees slant angle – Flow remains attached.

28 degrees slant angle – Boundary layer separation zone over slant.

35 degrees slant angle – Complete boundary layer seperation

Exp. drag Num. drag Error

0.230 0.232 +0.86%

0.336 0.319 -5.06%

0.257 0.256 -0.38%

sible CFD Solver

LS980 – ICFD Solver – Drag Prediction

Ahmed Body Problem

LS-DYNA ENVIRONMENT

LS-DYNA LS980 – CESE Solver

CESE - Compressible Fluid • Available for all compressible flows, especially for high speed flows with complex shock waves

• 3D default, there are 2D and 2D axisymmetric options

• Elements include hexahedra, wedges, and tetrahedral

• In addition to the normal CFD boundary conditions (prescribed, reflective, non-reflective, solid-wall, axisymmetric & periodic), we have added two moving solid wall BCs (slipping & rotating)

• Models for small scale & high speed cavitating flows

• Chemical reacting flows: zero dimensional constant combustors, one-step reaction model, and a detailed reaction model

• Thermobaric explosive flow with stochastic solid particles

LS-DYNA ENVIRONMENT

LS-DYNA LS980 – CESE Solver

Spray Particles Injected into a Supersonic flow (CESE)

LS-DYNA ENVIRONMENT

LS-DYNA FE-MODELS

A couple of notes on FE-MODELS

FAT WORLD-SID Release 2.0

Arup – Cellbond AEMDB Barrier Model

Arup – HPM (oscar) and HMD

LS-DYNA ENVIRONMENT

LS-DYNA 2012 International Conference

JUNE 03 - 05, 2012 at the Hyatt Regency Dearborn, Detroit, MI

12th Int’l LS-DYNA Users Conference www.ls-dynaconferences.com

www.ls-dynaconferences.com

http://www.ls-dynaconferences.com/



LS-DYNA ENVIRONMENT

LS-DYNA 2013 - 9th European Conference

Manchester Central Convention Centre Welcome Reception and Social Event:

Sunday 2nd June 2013 Conference:

Monday 3rd – Tuesday 4th June 2013 Registration open:

September 2012

LS-DYNA ENVIRONMENT

LS-DYNA Contact Information

UK:

Arup

The Arup Campus

Blythe Valley Park

Solihull, West Midlands

B90 8AE, UK

T +44 (0)121 213 3399

F +44 (0)121 213 3302

[email protected]

For more information please contact the following:

www.arup.com/dyna

China:

Arup

39/F-41/F Huai Hai Plaza

Huai Hai Road (M)

Shanghai

China 200031

T +86 21 6126 2875

F +86 21 6126 2882

[email protected]

India:

nHance Engineering Solutions Pvt. Ltd (Arup)

nHance Engineering Solutions Pvt. Ltd

Plot No. 39, Ananth Info Park

Opposite Oracle Campus

HiTec City-Phase II

Madhapur

Hyderabad - 500081

IndiaT +91 (0) 40 44369797 / 8

[email protected]

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