The Effects of Nonproportional Loading on the Elastic-Plastic Crack-Tip Fields

Abstract

In this paper, the loading path effects on the plane strain elastic-plastic crack-tip stress field are investigated computationally. Three different loading sequences include one proportional loading and two non-proportional loading paths are applied to the modified boundary layer (MBL) model under small-scale yielding conditions. For the same external displacement field applied at the outer boundary of the MBL model, the mode I K field and T-stress field combined as the different loading paths are applied to investigate the influence of the nonproportional loading. The results show that for either the compressive or tensional T-stress, the loading path which applied K field followed by T field generates the lower crack-tip constraint. There is only slightly difference between the proportional loading path and that with the T-stress field following by K field. The results show that it is very important to include the load sequence effects in fracture analysis when dealing with nonproportional loading conditions.

A new multiaxial fatigue life prediction model considering additional hardening effect

“…Due to the existence of two independent stress/strain components that vary periodically with time under multiaxial loading, it is difficult to determine the damage accurately. 4,5 Thus, it is of great significance to study the fatigue damage accumulation law of components under multiaxial loading. At present, some achievements have been made in the study of the cumulative damage theory of multiaxial fatigue, but the geometric structure and loading conditions of actual components are complicated and uncertain.…”