突合せ溶接継手における軸方向き裂のSCC進展シミュレーション

抄録

Integrity of cracked pipe is assessed by predicting crack growth. In the fitness-for-service (FSS) codes of Japan Society of Mechanical Engineers (JSME), the crack growth prediction is made based on the stress intensity factor at the deepest and surface points. A semi-elliptical crack is assumed not to become deeper than semi-circular. The deep crack is replaced with the semi-circular crack of the same depth. In this study, validity of the current JSME FFS code for predicting the crack growth at weld was discussed. Crack growth was simulated by finite element analysis together with an auto meshing technique. The residual stress distribution and retardation of the crack growth at the fusion line were considered in the simulation. It was demonstrates that the JSME FFS code brings about a conservative growth prediction even if the crack became deeper than semi-circular shape. It was also revealed that, when the growth in the surface direction was restricted, the growth in the depth direction could be predicted conservatively by the current crack growth procedure of JSME.