LS-DYNA

LS-DYNA is an advanced general-purpose multiphysics simulation software package that is actively developed by the Livermore Software Technology Corporation (LSTC). While the package continues to contain more and more possibilities for the calculation of many complex, real world problems, its origins and core-competency lie in highly nonlinear transient dynamic finite element analysis using explicit time integration. LS-DYNA is being used by Automobile, Aerospace, Military, Manufacturing, and Bioengineering companies.

Typical uses

Nonlinear means at least one (and sometimes all) of the following complications:
* Changing boundary conditions (such as contact between parts that changes over time)
* Large deformations (for example the crumpling of sheet metal parts)
* Nonlinear materials that do not exhibit ideally elastic behavior (for example thermoplastic polymers)

Transient dynamic means analyzing high speed, short duration events where inertial forces are important. Typical uses include:
* Automotive crash (deformation of chassis, airbag inflation, seatbelt tensioning, ...)
* Explosions (underwater mines, shaped charges, ...)
* Manufacturing (sheet metal stamping, ...)

History

* John O. Hallquist, working for Lawrence Livermore National Laboratory (LLNL), writes the FEA program DYNA3D which uses explicit time integration to study nonlinear dynamic problems. The manual is released for public distribution in August, 1976.
* As a former US Military project, the source code for DYNA3D is released into the public domain without restrictions in 1978.
* A new version of DYNA3D is released for the CRAY-1 supercomputer in 1979.
* During the next few years, several companies begin to develop and market commercial versions based on the public domain code (e.g. Pam-Crash).
* Interest in the free public domain version intensifies and user conferences start in Japan and Europe in 1982.
* David J. Benson joins the DYNA3D development team at LLNL in 1984. (Hallquist was the sole developer up to this point)
* By 1988 ~600 tapes of DYNA3D have been sent to requesters from LLNL, and Hallquist is consulting for ~60 companies and organizations on its use.
* In 1989 Hallquist leaves LLNL to start LSTC and continue developing his own version of the code, LS-DYNA. (The release of new versions of DYNA3D into the public domain are halted at this point)
* LSTC continually develops and expands the capabilities of LS-DYNA with the goal of creating a sort of universal tool for most simulation needs. (A "one code" strategy)

Characteristics

LS-DYNA consists of a single executable file and is entirely command line driven. Therefore all that is required to run LS-DYNA is a command shell, the executable, an input file, and enough free disk space to run the calculation. All input files are in simple ASCII format and thus can be prepared using any text editor. Input files can also be prepared with the aid of a graphical preprocessor. There are many third party software products available for prepocessing LS-DYNA input files. LSTC also develops its own preprocessor, [http://www.lstc.com/lspp LS-PrePost] , which is freely distributed and runs without a license. Licensees of LS-DYNA automatically have access to all of the program's capabilities, from simple linear static mechanical analysis up to advanced thermal and flow solving methods. Furthermore they have full use of LSTC's [http://www.lsoptsupport.com/ LS-OPT] software, a standalone design optimization and probabilistic analysis package with an interface to LS-DYNA.

Capabilities

LS-DYNA's potential applications are numerous and can be tailored to many fields. LS-DYNA is not limited to any particular type of simulation. In a given simulation, any of LS-DYNA's many features can be combined to model a wide variety of physical events. An example of a simulation that involves a unique combination of features is the NASA JPL Mars Pathfinder landing which simulated the space probe's use of airbags to aid in its landing.

LS-DYNA's analysis capabilities:
* Full 2D & 3D capabilities
* Nonlinear dynamics
* Rigid body dynamics
* Quasi-static simulations
* Normal modes
* Linear statics
* Thermal analysis
* Fluid analysis
** Eulerian capabilities
** ALE (Arbitrary Lagrangian-Eulerian)
** FSI (Fluid-Structure Interaction)
** Navier-Stokes fluids
** Compressible fluid solver, CESE (Conservation Element & Solution Element)
* FEM-rigid multi-body dynamics coupling (MADYMO, Cal3D)
* Underwater shock
* Failure analysis
* Crack propagation
* Real-time acoustics
* Implicit springback
* Multi-physics coupling
* Structural-thermal coupling
* Adaptive remeshing
* SPH (Smoothed particle hydrodynamics)
* EFG (Element Free Galerkin)
* Radiation transport
* EM (Electromagnetism)

Material Library

LS-DYNA's comprehensive library of material models:

* Metals
* Plastics
* Glass
* Foams
* Fabrics
* Elastomers
* Honeycombs
* Concrete & soils
* Viscous fluids
* User-defined materials

Element Library

Some of the element types available in LS-DYNA:

* Beams (standard, trusses, discrete, cables, and welds) (with over 10 beam element formulations)
* Discrete Elements (Springs and Dampers)
* Lumped Inertias
* Lumped Masses
* Accelerometers
* Sensors
* Seat Belts
** Pretensioners
** Retractors
** Sliprings
* Shells (3, 4, 6, and 8-node including 3D shells, membranes, 2D plane stress, plane strain, and axisymmetric solids) (with over 25 shell element formulations)
* Solids (4 and 10-node tetrahedrons, 6-node pentahedrons, and 8-node hexahedrons) (with over 20 solid element formulations)
* SPH Elements
* Thick Shells (8-node)

Contact Algorithms

LS-DYNA's contact algorithms:

* Flexible body contact
* Flexible body to rigid body contact
* Rigid body to rigid body contact
* Edge-to-edge contact
* Eroding contact
* Tied surfaces
* CAD surfaces
* Rigid walls
* Draw beads

Applications

Automotive crashworthiness & occupant safety

LS-DYNA is widely used by the automotive industry to analyze vehicle designs. LS-DYNA accurately predicts a car's behavior in a collision and the effects of the collision upon the car's occupants. With LS-DYNA, automotive companies and their suppliers can test car designs without having to tool or experimentally test a prototype, thus saving time and expense.

LS-DYNA's specialized automotive features:

* Seatbelts
* Sliprings
* Pretensioners
* Retractors
* Sensors
* Accelerometers
* Airbags
* Hybrid III dummy models
* Inflator models

Sheetmetal forming with LS-DYNA

One of LS-DYNA's most widely used applications is sheetmetal forming. LS-DYNA accurately predicts the stresses and deformations experienced by the metal, and determines if the metal will fail. LS-DYNA supports adaptive remeshing and will refine the mesh during the analysis, as necessary, to increase accuracy and save time.

Metal forming applications for LS-DYNA include:

* Metal stamping
* Hydroforming
* Forging
* Deep drawing
* Multi-stage processes

Aerospace industry applications

LS-DYNA is widely used by the aerospace industry to simulate bird strike, jet engine blade containment, and structural failure.

Aerospace applications for LS-DYNA include:

* Blade containment
* Bird strike (windshield, and engine blade)
* Failure analysis

Other applications

Other LS-DYNA applications include:

* Drop testing
* Can and shipping container design
* Electronic component design
* Glass forming
* Plastics, mold, and blow forming
* Biomedical
* Metal cutting
* Earthquake engineering
* Failure analysis
* Sports equipment (golf clubs, golf balls, baseball bats, helmets)
* Civil engineering (offshore platforms, pavement design)

References

Crashworthiness Engineering: Course Notes, Paul Du Bois

External links

* [http://www.lstc.com/ LSTC Company Website]
* [http://blog.d3view.com/ LS-DYNA Blog by Suri Bala]
* [http://www.dynalook.com/ Download of Papers from International and European Conferences]
* [http://www.dynaexamples.com/ Examples and Class Notes for Download]
* [http://www.topcrunch.org/ Information on Performance on different Hardware]