Study on residual strength and life prediction of corroded tubing based on thermal-mechanical coupling XFEM

Abstract

Based on the experimental results of the stress-strain constitutive relationship, thermal expansion coefficient and thermal conductivity for P110S tubing material, a three-dimensional thermal-mechanical coupling mechanical model of P110S tubing with uniform, local and pitting corrosion is established by using nonlinear finite element method with due consideration on the physical nonlinearity of the corroded tubing and the geometric nonlinearity caused by large deformation comprehensively in this paper. The model is verified using full-scale burst test data. Based on the verified model, the burst mechanical behavior and burst strength of corroded tubing under thermal-mechanical coupling were simulated by adopting the XFEM method and burst failure criterion based on damage mechanics evolution, by which the investigation on burst mechanical behavior of P110S tubing wih pitting corrosion is paid the most attention. Based on the sensitivity analysis results of residual strength of corroded tubing and the corrosion test results, a prediction model of the residual strength for P110S corroded tubing is established by using the 1stOpt software and universal global optimization (UGO) algorithm, by which the evaluation method of service life for P110S corroded tubing is proposed.