Ratcheting assessment of offshore pipelines subjected to cyclic axial loading: experimental and numerical investigation

Abstract

ABSTRACT In the current study, the effect of several parameters on the ratcheting response of tubes under cyclic axial loading is studied. Experimental and numerical approaches have been used to provide a comparison between the ratcheting behaviour of tubes under small amplitude wrinkles and subsequent persistent cycles of axial stress ranges. The ratcheting experiments in the tube specimens have also been numerically simulated with nonlinear isotropic/kinematic hardening model (combined hardening rule). It was found that, when appropriate hardening properties (from the material testing results) are considered, the numerical model was producing results reasonably close to those from the experiments. The model has then been used to study effects from some key parameters on the ratcheting response and the progressive plastic failure of tubes. Parameters such as the initial strain, the stress range and the mean stress for the cyclic load, the loading regime, and the material hardening properties have been examined.