Ratcheting deformation is studied on straight pipe made of Z2CND18.12N 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 centre 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 in which Chen–Jiao–Kim (CJK) kinematic hardening model is carried out to evaluate structural ratcheting behaviors. Results indicate that ratcheting strain is along the centre 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.

An important issue in engineering application of the “design by analysis” approach in pressure vessel design is how to decompose an overall stress field obtained by finite element analysis into different stress categories defined in the ASME B&PV Codes III and VIII-2. In many pressure vessel structures, it is difficult to obtain $PL+Pb$ due to the lack of information about primary bending stress. In this paper, a simple approach to derive the primary bending stress from the finite element analysis was proposed with application examples and verifications. According to the relationship of the bending stress and applied loads or the relationship of the bending stress and displacement agreement, it is possible to identify loads causing primary bending stress for typical pressure vessel structures. By applying the load inducing primary bending stress alone and necessary superposition, the primary bending stress and corresponding stress intensity $PL+Pb$ can be determined for vessel design, especially for axisymmetric problems.