Numerical implementation of bounding-surface model for simulating cyclic inelastic response of metal piping components

Abstract The present paper describes the numerical implementation of the bounding-surface cyclic-plasticity model in a finite element environment, suitable for simulating the structural behavior of metal components subjected to strong cyclic loading. The model is based on the Dafalias-Popov “bounding surface” concept, equipped with appropriate enhancements that allow for simulation of repeated, alternate inelastic deformation. The numerical implementation is performed using an elastic-predictor/plastic-corrector method. Special features of the model are examined, focusing on the influence of several material parameters on cyclic material response. The model is also employed for simulating laboratory physical experiments. First, stress-controlled and strain-controlled experiments are simulated, in strip specimens made of regular (mild) steel and high-strength steel. Upon appropriate calibration from these material tests, the model is employed in a finite element model for predicting the mechanical response of a large-scale physical experiment on a steel pipe elbow. The very good comparison between the experimental and the numerical results demonstrates the suitability of the numerical model for large-scale structural computations and its capability of predicting the mechanical response of structural metal components under severe repeated loading, with emphasis on the simulation of ratcheting.