LS-DYNA Beam Elements: Default and User Defined Cross Section Integration

Len Schwer Schwer Engineering & Consulting Services, USA LS-DYNA provides several beam element formulations, see the keyword description for *Section_Beam in the User’s Manual. Several of these beam element formulations support user supplied integration of the cross section, via the *Integration_Beam keyword. While most LS-DYNA users are familiar with the similar through-the-thickness integration algorithm for shell elements, which is made trivial by the rectangular cross section geometry assumed for shell elements, the numerical integration of even simple beam element cross sections requires more effort, and as will be demonstrated, more planning. In this article, a detailed explanation of the beam element cross section integration algorithm is presented. Simple suggestions for calculating, and checking, user provided integration rules are illustrated through several examples. The examples also provide suggestions for improving the LS-DYNA Standard Cross Section Types, available via the ICST parameter of the *Integration_Beam keyword.