LS-DYNA

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Screenshot from LS-PrePost showing the results of an LS-DYNA simulation of a Geo Metro impacting a rigid wall at 120 kilometres per hour (75 mph).

LS-DYNA is an advanced general-purpose multiphysics simulation software package 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 (FEA) using explicit time integration. LS-DYNA is being used by the automobile, aerospace, construction, military, manufacturing, and bioengineering industries.

History[edit]

LS-DYNA originated from the 3D FEA program DYNA3D, developed by Dr. John O. Hallquist at Lawrence Livermore National Laboratory (LLNL) in 1976.[1] DYNA3D was created in order to simulate the impact of the Full Fusing Option (FUFO) or "Dial-a-yield" nuclear bomb for low altitude release (impact velocity of ~ 40 m/s). At the time, no 3D software was available for simulating impact, and 2D software was inadequate. Though the FUFO bomb was eventually canceled, development of DYNA3D continued.[2] DYNA3D used explicit time integration to study nonlinear dynamic problems, with the original applications being mostly stress analysis of structures undergoing various types of impacts. The program was initially very simple largely due to the lack of adequate computational resources at the time. A two-dimensional version of the same software was developed concurrently.[1] In 1978 the DYNA3D source code was released into the public domain without restrictions after a request from France.[2]

In 1979 a new version of DYNA3D was released which was programmed for optimal performance on the CRAY-1 supercomputers. This new release contained improved sliding interface treatment which was an order of magnitude faster than the previous contact treatment. This version also eliminated structural and higher order solid elements of the first version, while including element-wise integration of the integral difference method developed in 1974.[1]

The 1982 release included nine additional material models which allowed for new simulations, such as explosive-structure and soil-structure interactions. The release also permitted the analysis of structural response due to penetrating projectiles. Improvements in 1982 further boosted the execution speed by about 10 percent. Hallquist was the sole developer of DYNA3D until 1984, when he was joined by Dr. David J. Benson.[3] In 1986, many capabilities were added. The added features included beams, shells, rigid bodies, single surface contact, interface friction, discrete springs and dampers, optional hourglass treatments, optional exact volume integration, and VAX/VMS, IBM, UNIX, COS operating system compatibility. At this point, DYNA3D became the first code to have a general single surface contact algorithm.[1]

Metal forming simulation and composite analysis capabilities were added to DYNA3D in 1987. This version included changes to the shell elements, and dynamic relaxation. The final release of DYNA3D in 1988 included several more elements and capabilities.[1]

By 1988 LLNL had sent approximately 600 tapes containing simulation software. Hallquist had consulted for nearly 60 companies and organizations on the use of DYNA3D.[2] As a result, at the end of 1988 Livermore Software Technology Corporation (LSTC) was founded to continue the development of DYNA3D in a much more focused manner, resulting in LS-DYNA3D (later shortened to LS-DYNA). Releases and support for DYNA3D were thus halted. Since then, LSTC has greatly expanded the capabilities of LS-DYNA in an attempt to create a universal tool for most simulation needs.[1][4]

Typical uses[edit]

Nonlinear means at least one (and sometimes all) of the following complications:

Transient dynamic means analyzing high speed, short duration events where inertial forces are important. Typical uses include:

Characteristics[edit]

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 preprocessing LS-DYNA input files (e.g., TrueGrid). LSTC also develops its own preprocessor, 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 LS-OPT software, a standalone design optimization and probabilistic analysis package with an interface to LS-DYNA.

Capabilities[edit]

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:

Material Library[edit]

LS-DYNA's comprehensive library of material models:

Element Library[edit]

Some of the element types available in LS-DYNA:

Contact Algorithms[edit]

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[edit]

Automotive crashworthiness & occupant safety[edit]

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:

Sheetmetal forming with LS-DYNA[edit]

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[edit]

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[edit]

Other LS-DYNA applications include:

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

References[edit]

  1. ^ a b c d e f LSTC. "LS-DYNA Keyword User's Manual, Volume 1". Livermore Software Technology Corporation (LSTC). Retrieved 2009-03-25. 
  2. ^ a b c Dr. David J. Benson. "The History of LS-DYNA". University Of California, San Diego. Retrieved 2009-03-25. 
  3. ^ Seshu Nimmala. "A comparison of DYNA3D, NIKE3D and LS-DYNA". Oregon State University. Retrieved 2014-01-15. 
  4. ^ Mehrasa, Hossein; Liaghat, Gholamhossein; Javabvar, Dariush. "Experimental analysis and simulation of effective factors on explosive forming of spherical vessel using prefabricated four cones vessel structures". Central European Journal of Engineering 2 (4): 656–664. doi:10.2478/s13531-012-0036-y. 

External links[edit]