STUDY ON THE FAILURE ASSESSMENT OF SMALL DIAMETER PIPE WITH CIRCUMFERENTIAL CRACK UNDER MONOTONIC AND CYCLIC MULTI-AXIAL LOADING

摘要

Failure behaviors of small diameter pipe of austenitic stainless and carbon steels with circumferential crack under monotonic and cyclic multi-axial loading were observed and the criteria of failure under these conditions were investigated. For the failure under monotonic loadings, it was observed that the maximum load was attained when the net section von Mises equivalent stress almost reached to the flow stress of the material. For the cyclic loading, P_a/P_(max) or T_a/T_(max) seems to be a good parameter to estimate failure life irrespective of specimen thickness, initial crack size and loading pattern, especially for STPT410. Here, P_a and T_a are load and torque amplitude respectively, and P_(max) and T_(max) are the maximum load and torque under monotonic loading with the same loading pattern for cyclic loading.