Study on ratcheting effect of pressurized straight pipe with local wall thinning using finite element analysis

Ratcheting deformation is studied on straight pipe made of Z2CND18.12 N stainless steel with local wall thinning subjected to constant internal pressure and reversed bending using finite element analysis. The local wall thinning is located at the center of straight pipe, whose geometry is rectangular cross-section. The effect of depth, axial length and circumferential length on the ratcheting behavior of straight pipe is studied in this paper. Three-dimensional elastic-plastic analyses with ANSYS employed Chen-Jiao-Kim (CJK) kinematic hardening model is carried out to evaluate structural ratcheting behaviors. Results indicate that ratcheting strain is along the center of straight pipe extending to the two ends. The ratcheting strain occurs mainly at hoop direction. Axial ratcheting strain is relatively small. The effects of the depth, axial length and circumferential length of local wall thinning on the ratcheting response are discussed by CJK model.