Development and Implementation of Special Elements for Crash Analysis

A new solution technique is proposed for a class of problems involving deep plastic collapse and large shape distortion of thin shells which is based on the concept of special finite elements with built-in knowledge on local folding mechanisms. These elements are characterized by floating, rather than fixed, boundaries and continuity of slopes of the displacement field. Typically, eighteen special elements would accurately represent the complex deformation pattern of a single corner or fold line. The condition of slope continuity further reduces the number of free parameters to three (3)! The new procedure is illustrated by example of progressively crushing a rigid-plastic box column.