Low-Cycle-Fatigue Crack Closure Effect of Ship Cracked Plate Considering the Accumulative Plastic Damage

Abstract

In this paper, the relationship between crack closure level and the crack length is studied with experiment and numerical simulation under different low cycle fatigue (LCF) loads. The evolution mechanism of crack closure behavior is explored through the variations of the accumulative plastic strain and compressive stress near the crack-tip. The compressive residual stress is separated into two parts for comparative analysis, namely: the stress field ahead of the crack tip and the stress field of the wake region. The magnitude of the compressive stress field is obtained by the integration along the crack propagation direction of the normal stress. The results show that there is an excellent correlation between LCF crack closure level and the magnitude of the compressive stress in the plastic wake, which provides a new way to further study the complex mechanism of crack closure under LCF loads.