Fatigue design of pressed steel sheet

Abstract

The present work is devoted to the fatigue design of pressed steel sheet structures as used in e.g. auto bodies. In pressed parts areas exist with more or less sharp curvatures. Characteristics of the fatigue process for such parts are crack inititiation in a highly strained area due to the forming of the sheet and a loading mode that is predominantly bending of the thin sheet. The topic is addressed from two viewpoints. In the first instance, fatigue test procedures are discussed and results are presented for a common deep drawing steel and a high strength dual-phase sheet steel. Secondly, fatigue life estimation based on finite element simulation of both the forming and the following fatigue loading are presented. The results indicate an advantage of using higher strength steels for pressed parts. Furthermore, the local strain aproach is reliable for fatigue life estimations. However, the predictions are improved by considering also fatigue crack growth. © 1997 Elsevier Ltd. All rights reserved.