This document is the concise guide to Nastran RBE2 and RBE3 Rigid elements. It describes some of their main uses, as well as the key differences between RBE2’s and RBE3’s.
Also explained are the common errors:
User Fatal Message 2101 (GP4) which occurs if your RBE elements has a constraint on a dependent node;
User Fatal Message 5289 (WRGMTS) which occurs if a node is dependent in multiple RBE elements, including circular nesting.
The document explains the practical effect of choosing RBE degrees of freedom (DoF).