Numerical investigation on the ratcheting behavior of pressurized stainless steel pipes under cyclic in-plane bending

This study intends to characterize numerically the ratcheting behavior of stainless steel pipes subjected to cyclic bending and internal pressure. A cyclic plasticity constitutive model able to simulate the cyclic plastic behavior is first presented in the framework of rate-independent plasticity theory. Validity of the constitutive model is confirmed against the strain- and stress-controlled cyclic loading test data. The verified constitutive model is then applied to parametric studies in which the local (circumferential strain) and global (cross-section diameter change) ratcheting responses of pressurized straight stainless steel pipes under cyclic in-plane bending are scrutinized. The results demonstrate that the shape and degree of the ovalization which occurs during the multiaxial ratcheting are dependent not only on the geometry but also on the applied loads such as the internal pressure and the cyclic in-plane bending.