Application of DIC techniques to detect onset of necking and fracture in uniaxial and bulge tests

Abstract

This document provides information on and instructions for detecting the onset of necking in conventional uniaxial tension tests and biaxial bulge tests, using DIC technology and analysis methods developed at General Motors. The analysis enables reduction of the number and the costs of tests required in conventional FLD determinations using Marciniak and Nakajima tooling, while also avoiding the most serious process-dependent effects associated with the latter tests. It also provides a cost effective approach to develop forming limits for anisotropic sheet materials. In addition to providing this new experimental technique, the document will review the new procedures developed at General Motors for analysis of FLD tests and bulge tests to obtain reliable input for complete material card descriptions of advanced constitutive and forming limit models.