Effects of material properties and mismatch on unified constraint parameter

Abstract

In order to develop unified constraint-based fracture assessment method, it needs to investigate the effects of material properties and mismatches on the unified constraint parameter and develop the parameter solutions for cracked structures. In this work, the effects of material properties (yield strength and hardening exponent) and strength mismatch on the in-plane and out-of-plane unified constraint parameter Ad* of semi-elliptical surface cracks in homogeneous and welded plates have been investigated. The results show that the parameter Ad* does not essentially change with yield strength and hardening exponent of materials for cracks in homogeneous plates under bending and tension loads. The parameter Ad* of weld centerline cracks in welded plates under bending and tension loads is essentially independent on the strength mismatch. These advantages of Ad* are conducive to the development of its solutions for homogeneous and welded structures containing cracks. The effect of weld width on Ad* is related to loading mode, mismatch (undermatch or overmatch) and crack size. The mechanism of the influence of material properties, strength mismatch and weld width on Ad* has been explained by its definition and the crack-tip plastic strain distribution. The development and application of Ad* solutions for homogeneous and welded structures also have been discussed.