Shell, Solid and Beam Formulations for Explicit and Implicit

Control cards are often handy to overwrite local values. A good example would be if we need all parts to use a certain element formulation THEORY which is specified in *CONTROL_SHELL. As with any global control cards that manipulate local values, the global values specified in *CONTROL keywords are used ONLY if the local values…

February 22, 2010 | by

Modeling rigid bodies

LS-DYNA allows the modeling of rigid-bodies by assigning any part with the MAT_RIGID material law (MAT_020). This is by far the most easiest method available when compared with all finite element codes. When using MAT_RIGID, there are three distinct ways to model a rigid part and they are briefly explaine below. 1. Finite Element based…

January 13, 2010 | by

Significance of IGAP Parameter in *CONTACT in Implicit Analyses

In traditional explicit analysis, there is no convergence criteria that is checked for each time step. However, in Implicit calculations, incremental displacements are evaluated such that a displacement norm and the energy norm are within a pre-defined tolerance before convergence is assumed to be obtained. This is the so-called iterative scheme in Implicit Non-Linear Analyses…

September 1, 2009 | by

Boundary prescribed motion and Contact

When nodes are involved in both contact (penalty) and prescribed motion, contact failure is expected to occur. This is because the boundary conditions are always processed after all the contacts are handled that results in nodal accelerations being updated to enforce the boundary conditions. I will soon publish some examples to illustrate this phenomenon.

August 9, 2009 | by

Mass calculations for Discrete Beams

Discrete beams, like discrete springs, require valid mass at the nodes to compute the timestep. Unlike continuum based elements, the length of the discrete beams, are not used in the timestep calculations. Hence realistic density in the discrete beam material model must be used. There are two methods this can be achived. Density (RHO) in…

May 13, 2009 | by

LS-OPT 4.0 is now released.

The LS-OPT Version 4.0 beta release is now available at: LS-OPT 4.0 The Presentations folder has an overview and outlook of LS-OPT. The main feature is the next generation post-processor (Viewer). Note that LS-OPT/Topology will be available later in 2009 as a separate module.

May 13, 2009 | by

Discrete variables in LS-OPT

Starting version 3.0, LS-OPT supports the definition of discrete variables. Discrete type of design parameters are helpful when there is a need to find the optimum values from a “set” of values. A good example would be the choice of element formulation. The possible values for LS-DYNA for a quad can only be a subset…

February 9, 2009 | by