A Study on the Relationship between Fatigue Crack Opening Behavior and Reversed Plastic Zone Size

Abstract

A relationship between fatigue crack opening behavior and the reversed plastic zone size is studied. An elastic-plastic finite element analysis (FEA) is performed to examine the opening behavior of fatigue crack. The contact elements in this analysis are adopted in the mesh of the crack tip area. The smaller element size than reversed plastic zone size is used for evaluating the distribution of reversed plastic zone. In the author’s previous results, the FEA could predict the crack opening level, which the size of crack tip elements was in proportion to the theoretical reversed plastic zone size. It is found that the calculated reversed plastic zone size is related to the theoretical reversed plastic zone size and crack opening level. The calculated reversed plastic zone sizes are almost equal to the reversed plastic zone size considering crack opening level obtained by experimental results. It is possible to predict the crack opening level from the reversed plastic zone size calculated by the FEA. We find that the experimental crack opening levels correspond with the opening values of crack tip contact nodes on the calculated reversed plastic zone.