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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
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 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
$: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 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
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
*LOAD_NODE_POINT
$:nid/nsid dof lcid sf cid
93 3 1 +0.5 0
*CASE_END_2
*CASE_BEGIN_3
*LOAD_NODE_POINT
$:nid/nsid dof lcid sf cid
93 2 1 -500.0 0
*CASE_END_3
$
*CASE_BEGIN_4
*LOAD_NODE_POINT
$:nid/nsid dof lcid sf cid
93 2 1 500.0 0
*CASE_END_4
$
$
LS-DYNA ENVIRONMENT
LS-DYNA *CASE – example
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
LS-DYNA *FREQUENCY_DOMAIN
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
LS-DYNA *FREQUENCY_DOMAIN
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
LS-DYNA *FREQUENCY_DOMAIN
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
LS-DYNA *FREQUENCY_DOMAIN
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
LS-DYNA *Element_discrete_sphere
Porosity
MAT_20 0.409
MAT_220 0.409
Element Discrete 0.399
1488913384
1207
Analysis Time (secs)
LS-DYNA ENVIRONMENT
LS-DYNA *Element_discrete_sphere
Dry vs. Wet Spheres
Dry
Wet
Effects of viscosity on the mechanical response of a liquid bridge is considered.
LS-DYNA ENVIRONMENT
LS-DYNA *Element_discrete_sphere
LS-DYNA ENVIRONMENT
LS-DYNA *Element_discrete_sphere
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
LS-DYNA Isogeometric Analysis
NURBS-Patch and the definition of elements
LS-DYNA ENVIRONMENT
LS-DYNA Isogeometric Analysis
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
LS-DYNA Isogeometric Analysis
nisr=niss=2 nisr=niss=10
NURBS Surface Interpolation Nodes/Elements
LS-DYNA ENVIRONMENT
LS-DYNA Isogeometric Analysis
Isogeometric benchmark problem – LSTC • Study comparing
• Standard (non adaptive)
• Standard (adaptive)
• NURBS
LS-DYNA ENVIRONMENT
LS-DYNA Isogeometric Analysis
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
LS-DYNA Isogeometric Analysis
Isogeometric benchmark problem – LSTC • Reference solution – Adaptivity
4mm 2mm 1mm
LS-DYNA ENVIRONMENT
LS-DYNA Isogeometric Analysis
Good correlation between traditional adaptivity based stamping and NURBS-P2-4mm
Standard-Adaptivity NURBS-P2-4mm
LS-DYNA ENVIRONMENT
LS-DYNA Isogeometric Analysis
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
LS-DYNA Implicit LS-DYNA
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
LS-DYNA Implicit LS-DYNA
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
#nodes 1133 #eles 967
STEP 3
#nodes 1961 #eles 1675
STEP 4
#nodes 5203 #eles 4483
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 LS980 – EM Solver
LS-DYNA ENVIRONMENT
LS-DYNA LS980 – EM Solver
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
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
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
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