Limit Load Analysis of Elbow with Local Wall Thinning under Combined Loads

摘要

Generally elbow is a stress concentration component and a weak part in piping system.The local wall thinning(LWT) is a kind of common volume defect in pressure pipe.The limit loads of elbows with LWT under pressure, bending moment, torque and their combined loads have been studied in detail by orthogonal experimental design with finite element method.The results of studies have shown that the influence of depth and circumferential length of LWT defect on the limit load is more obvious compared to that of axial length when an elbow is under pressure, bending moment or torque.The change of limit bending moment and torque with the depth of LWT defect and circumferential length is significant for an elbow under combined bending moment and torque.At last, by regression results of finite element analysis results, the safety assessment equations for elbow under combined in-plane closing bending moment and torque were proposed.