A numerical investigation on the influence of a single tensile overload on fatigue Mis-using the interaction integral method

摘要

Evaluation of fatigue life has a considerable importance for the integrity of structures subjected to cyclic loadings. The superposition of single tensile overload (OL) and constant amplitude loading leads to crack growth retardation or full crack arrest;;which results in an increase in fatigue life1'. Several mechanisms have been proposed to explain the cause of crack growth retardation after a single tensile OL is applied;;including plasticity-induced crack closure2';;compressive residual stress3' and crack tip blunting4'. Simunek et al 5) have recently performed an experimental fatigue crack propagation (FCP) testing on common construction mild steel (S355) as well as high strength steel (S960) using a single edge notch tension (SENT) specimen. They have determined surface crack initiation and propagation length. They have also conducted pure constant amplitude loading (CAL) tests as well as CAL tests including single tensile OL for both S355 and S960 steels. This study aims to investigate the influence of a single tensile OL on the fatigue life based on a combination of a real material behavior (i.e. elastic-plastic material) and fracture mechanics approach by means of FEM.