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

Tolerance used for Tying Slave Nodes in TIED contacts

TIED contacts help “bond” two surfaces of different mesh densities. When using the default constraint method, the projection distance of the slave node onto to the closest master segment must be zero and this is achieved by LS-DYNA by updating the slave node coordinates such that it lies on the master surface. This coordinate update…

October 15, 2008 | by