Several joints are available in LS-DYNA that can be defined between two rigid bodies or nodal rigid bodies. The difficult part of the joint definition from the pre-processing point of view is the creating of nodes that defines the joint axes and subsequent merging of them to the respective rigid bodies. To simlpy this problem, […]

Mass scaling for MAT_SPOTWELD elements

Deformable spotwelds modeled using beams or solids elements can invariably limit the global timestep due to its small dimensions. LS-DYNA provides two methods to scale the spotweld timestep. The first method is the well-known global mass-scaling using DT2MS in CONTROL_TIMSESTEP. When DT2MS is non-zero (usually a negative number), the density of the spotwelds are modified […]

In mesh independent deformable spotwelds (see here ), the actual spotwelds are represented using either beams or solids (single or cluster). The nodes of the beam or solid element representing the spotweld are then tied to the sheet metal using a tied interface (TIED_SHELL_EDGE_TO_SURFACE or TIED_NODES_TO_SURFACE). The forces experienced by the beam are the result […]

Deformable Spotwelds in LS-DYNA

Over the years, spotweld representation for crash and NVH applications have evolved from a crude to a detailed modeling resulting in reduced pre-processing effort while greatly enhancing the accuracy of numerical models. Here is link that gives a brief overview of spotwelding process in LS-DYNA. Please note that the document is over 2 years old […]

Limitations of Penalty Joint Treatment in LS-DYNA

LS-DYNA supports various joint definition types such as spherical, cylindrical, etc (please refer to the LS-DYNA User’s manual for a complete list). Irrespective of the joint definition type and the elements associated, translational constraints are applied to the joint nodes to model appropriate behavior. The constraints are applied using the default penalty formulation whose stiffness […]