ls-dyna recent developments
TRANSCRIPT
Recent Developments
Brian WainscottOasys LS-DYNA UK Users’ Meeting
January 28, 2016Solihull
• Introduction
• LS-OPT
• Elements
• ALE
• Implicit
• CFD
• Electromagnetics
• Particle Methods
• Metal Forming
• Frequency Domain
• Meshfree Methods
Outline
Explicit/Implicit
Heat Transfer
ALE & Mesh Free i.e., EFG, SPH, Airbag Particle
User InterfaceElements, Materials, Loads
Acoustics, Frequency Response, Modal Methods
Discrete Element Methods
Incompressible Fluids
CESE Compressible Fluids
Electromagnetics
Future: Control systems
LS-DYNA – Current Capabilities
Includes coupled Multi-Physics, Multi-Scale , and Multi-Stage in one Scalable Code
Multi-physics and Multi-stageStructure + Fluid + EM + Heat Transfer
Implicit + Explicit ….
Multi-scaleFailure predictions, i.e., spot welds
Multi-formulationslinear + nonlinear + peridynamics + …
The Neon crash model is courtesy of FHWA/NHTSA National Crash Analysis Center.
Single Model for Multiple DisciplinesManufacturing, Durability, NVH, Crash, FSI
LS-DYNA – One Code , One Model
LS-OPT
LS-OPT
• Simulation-based Multidisciplinary Optimization.
• Seamlessly integrated with LS-DYNA
• Interfaces with a large number of pre/post-processors & 3rd party solvers.
• Support web page: www.lsoptsupport.com
• The main analysis and optimization features of LS-OPT:
• Design Improvement and Optimization (MDO/MOO)
• System Identification
• Reliability-Based Optimization/Robust Design Optimization
• Outlier Analysis
• Network-based job scheduling
• Enhancements for Version 5.1 include interfaces for new solvers , enhanced modeling and optimization methods and enhanced graphical post-processing features.
LS-OPT MDO: Vehicle Crash and Body Dynamics
6 Crash Modes + Body Dynamics Mode:
- approximately 3 million element models
Allen Sheldon, Ed Helwig (Honda R&D)
LS-OPT Shape Optimization of Lower Bumper Stiffener
Design Vars: 4 Morphing Shapes
Objective: Min. weight
Constraints:
Ultrasim Failure Values < 0.6
All Ped Pro requirements fulfilled
Original contour
Baseline
Optimum: 7% mass reduction
Andreas Wuest (BASF)
Elements
Thick Shell: Types 5 & 7
• Thick Shells are like Solid Elements
• 8 nodes per element
• Assumed strain within the element
• Use the solid material models
• Thick Shells are like Shell Elements
• Layers in the thickness direction
• Type 5: 1 integration point per layer, VERY FAST!
• Type 7: 4 integration points per layer
Bridging Solids and Shells
thickness
thicknessthickness
Thick Shell: Types 5 & 7
• Thick Shells are NOT like Solid Elements
• Poor aspect ratio in the thickness direction
• Single element without stacking multiple solid elements
• More integration points through the thickness for bending
• Thick Shells are NOT like Shell Elements
• They are “thick” with a non-zero transverse normal stress
Bridging Solids and Shells
Shell Thick Shell Solid
A Clamped Square Plate subjected to a sudden point load at the center
4x4x1 10x10x1
Poor Aspect Ratio: Length = 1.0, Thickness = 0.02, Explicit Analysis
A: T-Shell Type 5 B: T-Shell Type 7
Thick Shell for T-Joint
Shell 16 Thick Shell 5Solid -2(Reference Solution)
490 Nodes198 Elems
Thick Shell 7
490 Nodes198 Elems
225 Nodes192 Elems
39325 Nodes30720 Elems
Non-conforming meshes
• Single layer of T-Shells for each panel
• Support variable thickness
• Support *CONTACT_TIED_NODE_SURFACEto tie non-conforming meshes between
panels
Models with different elements give consistent results.
Thick Shell for Composites
• Each layer has its own material property:
• Thickness, material type, fiber direction.
• Symmetric or Asymmetric lamination
• A first order shear deformation theory assumes:
• Transverse shear stress for each layer
• High order transverse shear strain for each layer
Sandwich panel Symmetric layers Asymmetric layers
High order Shear Stress for laminated composites
Parabolic Shear stressfor homogeneous materials
A Sandwich Beam under a Distributed Load
Case 1: Sandwich Beam Case 2: Asymmetric Beam
A/C: Solid Element B/D: Thick Shell
Material 1 (Red): E1=73.4 GPa Material 2 (Blue): E2=0.286 GPa E1/E2=257
Reference Solution: 36 solid elements through the thickness
One T-Shell element in the thickness12 layers within *PART_COMPOSITE
Case 1: Sandwich Beam
Remesh during runtime
Dynamic mesh refinement - initial horizontal crack
torque torque
opposite side of the crack
Remesh during runtime
Dynamic mesh refinement - initial vertical crack
torque
initial vertical crack
Dynamic mesh refinement - initial horizontal crack
right
bending
Remesh during runtime
Left
ALE
S-ALE Overview
• Structured ALE mesh automatically generated
• User specifies mesh spacing information along three directions
• Smaller input deck; Easier modifications to the mesh; Less I/O time.
• Shorter calculation time
• Sorting, searching faster and more efficient;
• SMP, MPP, MPP-Hybrid supported
• Redesigned algorithm enabled SMP parallelization and hence MPP Hybrid.
• Enhanced MPP efficiency
• More accurate and less memory
•A rewritten leaner, cleaner code using less memory to accommodate larger problems.
Solver MAX Memory (words) Clock Time (s)
ALE 414M 312
S-ALE 158M 199
* 48 CPU MPP Single Precision for a underwater explosion problem of 2.4M elements
S-ALE Time Saving
• Time saving in a Bridgestone tire rolling in mud model
ALE S-ALE Reduction
Total Time 30941s 20120s 34.97%
FSI 15449s 5726s 63%
Advection 7595s 6642s 12.55%
134400 ALE solid elements; Simulation time 2000ms.Single precision MPP 48 cpus without special decomposition
Implicit
Implicit update
• Rotational Dynamics
• available since R8.0
• adds additional stiffness terms due to rotations including Gyroscopic and spin softening
• Enable the study of vibration of rotating parts (turbine blades, propellers in aircraft and rotating disks in hard disk drives etc.).
• Campbell Diagrams can be generated to represent system's eigen-frequencies as functions of rotating speeds.
Implicit update
• Brake squeal
• Is the result of friction-induced vibration.
• Has been a challenging issue due to its immense complexity
• Complex eigenvalue analysis and transient analysis are the two
simulation methods used to investigate the brake squeal problem.
• With our complex eigensolver, LS-DYNA provides a multi-step
solution, a combination of the complex eigenvalue analysis and
transient analysis
disk
Pads (top and bottom)
Damping Ratio is defined as -2*Re(λ) / |Im(λ)|, where λis the eigenvalue. When negative, the mode is unstable.
Reuse of Symbolic Factorization
• Very Large Models in MPP can have wall clock time dominated by the Symbolic Factorization (a serial bottleneck we are still trying to fix)• Customer was using 1024 MPI processes and 6 SMP threads for a 7M node
version of this fan blade model.
• Symbolic Factorization was taking 2600 seconds (WCT)
• Numeric Factorization was taking 150 seconds.
• As a short term fix we have implemented two enhancements. • The first enhancement is to monitor the matrix structure from matrix
reformation to matrix reformation. If the matrix structure is the same from the last numeric factorization to the current one we reuse the symbolic factorization.
• The second enhancement is an MPP only feature. We predict the contact pattern for penalty based (non-tied) contact to allow small changes in the matrix structure due to changes in the contactbetween time steps.
• Reuse reduced WCT for time step by over 90%
CFD
A CFD solver for incompressible flows (ICFD solver).
Fully implicit.
Automatic volume mesh generation including boundary layer mesh.
Turbulence models for RANS/LES.
SMP and highly scalable MPP versions available.
Free surface flows
Porous media flow
Coupled to the structural and thermal solver
ICFD Solver Introduction
ICFD for Drag Analysis
• This study applies ICFD to unsteady flow analysis in the pitching motion of a 1/4 scale car model.
• The model was based on a real production car and obtained by smoothing the body surface relative to that of the actual vehicle, and by removing elements such as the engine compartment, underside components, and the suspension.
• Of primary interest is the difference between the aerodynamic forces acting on adynamic car model versus a stationary model.
• The results are validated through comparisons with those obtained by high accuracy academic CFD codes with a computational grid of 48 million elements.
“Analysis of Unsteady Aerodynamics of a Car Model in Dynamic Pitching Motion Using LS-DYNA® R7”, Yusuke Nakaeetc., 13th International LS-DYNA Users Conference
ICFD for Drag Analysis
• Static cases 1~3
• Dynamic cases
CFD + Thermal analysis example
CAD geometry Surface mesh
Automatic Volume meshing CFD + Thermal analysis
Results of CFD + Thermal Analysis
Thermal analysis for engine and exhaust.
Pressure contour Turbulent flow around a car
ICFD+FSI analysis
Structural pressure and Stress
ICFD – Pressure forces on a body
Fuel tank sloshing
Sloshing tank divided by a highly flexible Neoprene material
ICFD for porous media
• generalize Navier-Stokes equations to allow the definition of sub-domains with different permeability/porosity.
• The flow of a Newtonian fluid through a rectangular channel with a thick porous layer is considered
ICFD + Thermal for porous media
ICFD for porous media
• It is known that the cooling-air flow passing through engine compartment, radiator interferes with external flow.
• This study performs CFD simulations of the car models with an engine compartment containing a radiator.
“Analysis of Unsteady Aerodynamics of a Car Model with Radiator in Dynamic Pitching Motion”, Y. Nakae, 10th European LS-DYNA Conference 2015
ICFD for porous media
“Analysis of Unsteady Aerodynamics of a Car Model with Radiator in Dynamic Pitching Motion”, Y. Nakae, 10th European LS-DYNA Conference 2015
Isotropic and anisotropic porous media models
Free surface flow impacting on an a porous matrix made of three materials: two anisotropic materials immersed in a isotropic material.
EM and conjugate heat transfer: An electric current connected to the coil generates heat which is transferred to the fluid. The heat induces a flow motion due to natural convection.
ICFD – Conjugate Heat Transfer + EM
Electromagnetics
Electromagnetic solver in LS-DYNA
• Applications include:
• Magnetic Pulse Forming
• Magnetic Pulse Welding
• Induction welding
• Battery crash modeling
• Induction heating
• Resistive heating
• Electromagnetic spot welding
• Coil design and optimization
• Contact: rail gun, short circuits
• Generation of ultra high magnetic fields
Magnetic Metal Forming (MMF)
Use one sided die
(Optional - none
metallic die)
Can be combined
with any other
forming technology
Achieve higher
formability than
traditional methods
Can produce
Sharp corners and
fine details
Greatly reduced
springback and good
stress distribution
Die
Sheet
Blankholder
PunchCoilwindings
Combined deep drawing + MMF
Courtesy of Y. Kiliclar, IUL, TU Dortmund
Magnetic Pulse Welding
MPW is a solid state cold welding
generated by high speed collision between two metals at room temperature
Sub millisecond
weld time
Dissimilar
metals
High performance
joining,thinner
parts
No heat
affected zone
Different
shapes
Simulations are used to determinethe collision parameters (3D) to insure a good weld.
Courtesy of G. Mazars, Bmax, France
Particle Methods
*AIRBAG_PARTICLE – *CONTROL_CPM
*CONTROL_CPM
FORM NP2 NCPMTS CPMERR SFFDC
SFFDC : Scale factor of force decay constant (Default=1.0) Allowable arrange 0.01 to 100. (dev 97346)
Particle impact force is gradually applied to airbag segment by a special smoothing
function with the following form.
𝐹apply = 1 − 𝑒−𝑑𝑡
𝑆𝐹𝐹𝐷𝐶∗𝜏 ∗ 𝐹current + 𝐹stored
Where τ is the force decay constant stored in LS-DYNA.
SFFDC= 0.5 1.0 5.0
• Automatically shift all time dependent curves used in
– *AIRBAG_PARTICLE
– *MAT_FABRIC
Allow user to disable the bag by Tdeath
Allow user to set RIGID to DEFORMABLE switch
*AIRBAG_PARTICLE – *SENSOR_CPM_AIRBAG
*SENSOR_CPM_AIRBAG
$ CPMID SWITID TBIRTH TDEATH TDR FDEFPS RBPID
*AIRBAG_PARTICLE – IAIR=-1
IAIR=1 IAIR=-1
External Vent
• At the beginning of the bag inflation, the bag pressure may drop below
ambient pressure due to jetting. When IAIR=-1, it will allow external
vents to draw in outside air.
It gives better speed opening rolled bags by tracking the gas front.
It stores the number of collisions from resident air and inflator particles
and uses this data to track the inflator gas front and rolled region.
Inflator particles do not transfer energy to resident air particles, to prevent
prematurely deploying the rolled region. The energy of the initial air
should be small compared with the incoming energy.
The tracking algorithm can be switched off and all features will become
the same as IAIR=2.
IAIR=4 is not a replacement of IAIR=2.
*AIRBAG_PARTICLE – IAIR=4
*AIRBAG_PARTICLE – IAIR=4
IAIR=2
IAIR=4
Instances in time (42.5ms)Courtesy of Autoliv
Chamber 8 and 9
*AIRBAG_PARTICLE – IAIR=4
IAIR=2
42.5ms: Pressure history of chamber 8 and 9Courtesy of Autoliv
IAIR=4
*PARTICLE_BLAST– Real Gas Law
Set-up for free face tests Set-up for numerical simulation
D. Johansson et al., Int. Mining and Mineral Engineering, 2011
Explosive
Air
Front View Top View
140 mm
280 mm
8,10,12mm
Particle blast simulation of blast fragmentation of a mortar cylinder
Diameter of hole (mm) PETN strength (g/m)
Case1 12 40
Case2 10 20
Case3 8 20
Case4 8 10
*PARTICLE_BLAST– Real Gas Law
Courtesy of Changping Yi , Luleå University of Technology
*PARTICLE_BLAST– Real Gas Law
Courtesy of Changping Yi , Luleå University of Technology
*PARTICLE_BLAST– Real Gas Law
2ms 20ms5ms
C. Yi et al., 11th International Symposium on Rock
Fragmentation by Blasting, 2015
Local enlargement
*PARTICLE_BLAST– Real Gas Law
Numerical Results Experimental Results
Xave(mm) Xmax(mm) Xave(mm) Xmax(mm)
Case1 8.37 48.36 8.30 40.4
Case2 18.08 54.59 15.13 48.3
Case3 17.75 46.36 14.94 52.4
Case4 28.50 56.70 25.49 78.1
C. Yi et al., 11th International Symposium on Rock Fragmentation by Blasting, 2015
1. Friction Stir Welding
2. SPH to SPH contact
SPH Enhancements
Double sided FSW 600 RPM, 1200 mm/min(plastic work and friction energy to heat)Courtesy of Kirk A. Fraser @ PredictiveEngineering
Temperature ContoursMaterial Mixing
Extended SPH thermal solver for SPH form 7 and 8
Friction Stir Welding
V
Multiple impacts with Keyword: SECTION_SPH_INTERACTION
Define the different type of interactions between SPH parts.
Metals withStandard interactions
Ceramic with node to node contacts
SPH Interaction
1. Discrete Element Sphere
2. Discrete Element Method with Bond
Discrete Element Method
*DEFINE_DE_TO_SURFACE_COUPLING
Node To Surface Coupling
INJECTION box as source of DES
Why a new N2S contact?• Consider rolling friction• Automatically treat liquid bridge for wet particles• Coupling considers traction force (use stationary segments to
model moving conveyor belt )
Throwing a pie in the face, Courtesy of Kazuya, Lancemore
*DEFINE_DE_TO_SURFACE_TIED
Tied Node to Surface Coupling
Wear prediction
Discrete Element Method (DEM)
Archard’s wear law:
A
vfWEARCh tn **
Form different shapes of particles using DEM
DEM Bond Type I Example
DE Bond Type
Simple links, truss or beam, etc…Peridynamics
Particle-particle interaction
Particle Gas
P1 P2BOND
1<->2
P3
P6
P5
P4DEM bond
DEM1) Node to Node
2) Node to Beam
3) Node to Segment
4) Node to Volume
Coupled Multi-Physics Solvers
Tank sloshing with fluid and vapor (node to node contact)Density ratio ~ 1000
SPH to SPH Contact
SPH and SPH Coupling
CPM and DES Contact
CPM and DES Coupling
Courtesy of Changping Yi , Luleå University of Technology
DES to Beam Contact
Node to Beam Coupling
DES to Segment Contact
Node to Surface Coupling
# of processors LS-DYNANational Lab DEM
Code
20 6158 6360
40 3733 4498
60 2669 3769
80 2152
Metalforming
Rigid Body Mesh Check/Fix
• Element Normal Check / fix
– Mesh generators are not always reliable in giving high quality tool mesh (very long, overlapped elements, with inconsistent element normals)
– Manual repair by user in pre-processor is time consuming and error-prone
– Simulation with bad elements has high possibility to get unrealistic results
• Physical offset of rigid tools
– In stamping simulation, it is common both upper and lower tools overlap each other in the home position
– Negative offset is used (MST is negative)
– With penetration, contact can be confused. Occasionally, unexpected results are obtained
• Keyword: *CONTROL_FORMING_AUTOCHECK
– automatically check and fix the rigid body mesh
– Automatically offset the rigid tool physically based on the MST values specified in contact definitions
Rigid Body Mesh Check/Fix
Rigid Body Mesh Check/Fix
• Example of automatic mesh repair
Section cut:
contact problem found
Section cut:
normal contact between the tools and
the blank
Adaptivity for Sandwich Structures
• Example of sandwich part structure
• Top and bottom layers use shell element
• Middle layer use solid element
• Elements in top layer share nodes with solid element in top surface
• Elements in bottom layer share nodes with solid element in bottom surface
Adaptivity for Sandwich Structures
Adaptive algorithmMesh refinement in the planeNo refinement in the thickness direction
Adaptivity for Sandwich Structures
• Example
Frequency Domain Analysis
Frequency Domain Analysis
• FRF
• SSD
• Random Vibration
• Response Spectrum Analysis
• BEM Acoustics
• FEM Acoustics
• SSD Fatigue
• Random Fatigue
• NVH of automotives and air planes
• Acoustic design and analysis
• Defense industry
• Fatigue of machines and engines
• Civil and hydraulic engineering
• Earthquake engineering
Applications
Velocity
Acoustic Impedance
Pressure
New boundary conditions for FEM acoustic features
Use acoustic Impedance boundary condition
to model the sound absorbing material (like
the interior surface of roof or floor)
Use pressure boundary condition to
model the window or other openings
cv
pz
n
Characteristic impedance
FEM Acoustics
FEM Acoustics – Pressure Boundary
0 pressure b.c. to model
the opened window
In this example, the opened window is
simulated using 0 pressure boundary
condition. The blue area in the d3acs
pressure plot clearly indicates the 0
pressure zones.
No. of Nodes: 114221
No. of elements: 643619
FEM Acoustics – Acoustic Eigenvalue Analysis
Mode LS-DYNA Other software
1 3.93144E-06 6.698696E-06
2 8.10808E+01 8.108078E+01
3 1.25457E+02 1.254568E+02
4 1.47780E+02 1.477799E+02
5 1.52190E+02 1.521901E+02
6 1.72872E+02 1.728723E+02
7 1.98448E+02 1.984481E+02
8 2.08590E+02 2.085895E+02
9 2.14581E+02 2.145808E+02
10 2.23230E+02 2.232297E+02A closed compartment model
Eigenvector for the 2nd mode
LS-DYNA
*FREQUENCY_DOMAIN_ACOUSTIC_FEM
_EIGENVALUE
aiaiia NiMK ,1][2
aiaaa FpMCjK ][2
New databases:
•EIGOUT_AC
•D3EIGV_AC
Other software
FEM Acoustics – Acoustic Eigenvalue Analysis
Mode LS-DYNA Other software
1 6.79551E+01 6.795506E+01
2 1.03346E+02 1.033460E+02
3 1.47853E+02 1.478530E+02
4 1.58211E+02 1.582106E+02
5 1.74781E+02 1.747807E+02
6 1.87460E+02 1.874595E+02
7 2.10906E+02 2.109057E+02
8 2.14993E+02 2.149934E+02
9 2.28861E+02 2.288609E+02
10 2.50667E+02 2.506669E+02
A compartment model with
windows open
Eigenvector for the 1st mode
LS-DYNA Other software
R
eAp
ikRi
zyxiki Aep
*FREQUENCY_DOMAIN_ACOUSTIC_INCIDENT_WAVE
Spherical wave Plane wave
Card 1 1 2 3 4 5 6 7 8
Variable TYP MAG XC YC ZC
Type I F F F F
Default 1 None None None None
MAG Magnitude of the incident sound wave
GT.0: constant magnitude,
LT.0: |MAG| is a curve ID, which defines the frequency dependent magnitude. See
*DEFINE_CURVE.
VARIABLE DESCRIPTION
BEM Acoustics – Incident Acoustic Wave
Use frequency dependent magnitude in acoustic incident wave
Acoustic fringe plot
*FREQUENCY_DOMAIN_ACOUSTIC_FRINGE_PLOT_{OPTION}
Options:
PART
PART_SET
NODE_SET
SPHERE
PLATE
Existing structure components
LS-DYNA generates mesh automatically
Results (D3ACS):
• Real part of acoustic pressure
• Imaginary part of acoustic pressure
• Absolute value of acoustic pressure
• Sound Pressure Level (dB)
Supported by LS-PrePost 4.2 and above
Purpose:
Define field points for acoustic pressure computation and use D3ACS binary database to visualize the pressure distribution.
Acoustic fringe plot
R = 5000 mm
DENSITY = 15
No. of new nodes: 1178
No. of new elements: 1176
*FREQUENCY_DOMAIN_ACOUSTIC_FRINGE_PLOT_{SPHERE}
Equivalent Radiated Power (ERP) calculation
nnFF VVcERP 2
1
Calculation of ERP is a simple and
fast way to characterize the structure
borne noise. It gives the user a good
look at how panels contribute to total
noise radiation. It is a valuable tool in
early phase product development.
The ERP density is defined as
S
abs dSERPERP
The ERP absolute is defined as
*FREQUENCY_DOMAIN_SSD_{ERP}
)/(log10 10 refabsdB ERPERPERP
The ERP in dB is defined as
ERP calculation results are saved in
• Binary database
d3erp
• ASCII xyplot files ERP_abs ERP_dB
ERP calculation example
For a simplified engine model, a
constant horizontal acceleration 0.02g
is given on the base, for the range of
frequency 10-1000 Hz.
ERP density (d3erp)
ERP calculation example
ERP density (d3erp)Nodal force applied at
engine attachment point
With ERP, one can
study the contribution
to the radiated noise
from each panel.
SSD Fatigue
New stress index for SSD fatigue analysis
*FREQUENCY_DOMAIN_SSD_FATIGUE
Card 3 1 2 3 4 5 6 7 8
Variable STRTYP NOUT NOTYP NOVA
Type I I I I
Default 1 1 1 1
STRTYP Stress index used in fatigue analysis:
EQ.0: Von Mises stress,
EQ.1: Maximum principal stress,
EQ.2: Maximum shear stress.
VARIABLE DESCRIPTION
STRTYP=0
(Von Mises)
Peak damage
ratio 1.705
STRTYP=1
(Max principal)
Peak damage
ratio 1.585
STRTYP=2
(Max shear)
Peak damage
ratio 1.518
New
Statistical Energy Analysis (ongoing development)
*FREQUENCY_DOMAIN_SEA_SUBSYSTEM*FREQUENCY_DOMAIN_SEA_CONNECTION*FREQUENCY_DOMAIN_SEA_INPUT_POWER
1 10 100 1.e3 1.e4 2.e4
Deterministic(FEM/BEM)
Statistical(SEA)
SEA is a statistical method for studying
vibration and acoustics in high frequency
ranges, without using elements or mesh.
In SEA a system is represented in terms
of a number of coupled subsystems and
a set of linear equations are derived that
describe the input, storage, transmission
and dissipation of energy within each
subsystem.
Frequency (Hz)
Subsystem i
(Ei, i)
Subsystem j
(Ej, j)
Pi
Pid
Pj
Pjd
Pij
Pji
SEA model of 2 subsystems
Statistical Energy Analysis example
Simplified passenger compartment
Loading is given on Floor Fender_right_front Fender_left_front Windshield
Meshfree Methods
• Adaptive FEM/EFG solid is available for Implicit thermo-mechanical coupled analysis.• Allows local refinement and has high accuracy. • Is suitable for forging and extrusion simulations with spring-back analysis.
Work piece
Top tool
Effective plastic strain contour
Adaptive FEM/EFG Solid Method
98
(b)(a) (c)
Comparison of pressure contours: (a) displacement-based meshfree Galerkin method (b) displacement-based meshfree Galerkin method with pressure smoothing and (c) presented method.
• Available for explicit and implicit analyses.• 5-noded Meshfree-enriched Finite element
method (MEFEM) is inf-sup stable.• Only available in LS-DYNA.
Courtesy of Yokohama Rubber Co.
MEFEM Method for Unit Cell Composite Analysis
Discrete Dislocation Dynamics (DDD) Method
• Mobility: mobbcc0
• One initial dislocation line:
• Glide plane:
• Burger vector:
• Shear modulus: 1
Poisson’s ratio: 0.305
• Dislocation core radius: 288.7
Annihilation distance: 144.3
• Applied stress field
• largest time step 1.0e7
• Mesh size between
110
111
3
2 1
10 2 1
1 1
111
1000,2000
• Developed for discrete dislocation analysis for applications IC industry.• Works for single crystal materials.• Only available in LS-DYNA.
Courtesy of Taiwan Semiconductor Manufacturing Company
Frank-Read Source
Shear Band
Temperature field
von Mises stress
Courtesy of Taiwan Semiconductor Manufacturing Company
• Developed for continuous dislocation analysis for applications IC industry.• Works for single crystal materials.• Will be available in LS-DYNA soon.
Single Crystal Plasticity Method
Effective Plastic Strain contour
Von Mises stress contour
Contact Force
A Low-speed Ball Penetrating through a Metal Plate
• Pure particle method.• Using existing FEM mesh.• No element/particle erosion or manual cut of the model.• Time steps do not drop.
Bottom view
Top view
EPS Contour
• Allows non-uniform FEM mesh and multiple SPG parts.
Upper plate Lower plate
Von Mises stress contour
Self-pierce Riveting (SPR) Analysis
Cutting Speed = 10 m/s
Explicit Dynamic Analysis
Aluminum
ρ0=2.7×10-6 kg/mm3
E=78.2GPa
v=0.3
σy=0.29(1+125ep)0.1
Strain-based failure criteria εfail = 0.5
Low-speed Oblique Metal Cutting Analysis
Time-Punch Force
Pressure Contour (Cross-section view)
∆t=7.69~8.16 ×10-8
Effective Stress Contour (Cross-section view)
Hole Punching in Metal
FDS model
Rigid
Constant v
Solid plates (SPG)
Von Mises stress contour
Effective Plastic Strain contour
Courtesy of Ford Motor Co.
Single Layered Flow-drilling Screw (FDS) Analysis
FDS model
Rigid
Constant v
Solid plates (SPG)
Von Mises stress contour
Effective Plastic Strain contour
Courtesy of Ford Motor Co.
Two-Layered Flow-drilling Screw (FDS) Analysis
Courtesy of Ford Motor Co.
• Allows multiple cracks.• Allows sharing nodes with
FEM
Metal Tearing Test