Homogenization yield criterion and its application to pipeline failure analysis

Abstract:

To obtain an accurate and reliable prediction formula of burst pressure for pipelines, a new yield criterion was proposed to analyze the plastic failure of pipelines. By calculating the integral mean value of the apothem with variable angle, a yield criterion in the form of principal stress components was established, which is called homogenization yield criterion. The locus of the criterion on the π-plane is located in the interior of the Mises circle, and the geometric shape is a dodecagon with equal sides and unequal angles. By comparing with the experimental data of metal yielding, it showed that the rewritten formula by the Lode parameters for this criterion was a connected piecewise line, which was in good agreement with the experimental data. Based on this criterion, the stress and strain fields of a pipeline were analyzed, and an analytical solution of burst pressure for the pipeline was obtained in consideration of the strain-hardening effect of the material. Then, the main parameters that influence the burst pressure were discussed. The experimental data was compared with the burst pressure obtained based on the Tresca, Mises, and TSS yield criteria. Results showed that the prediction results of burst pressure were dependent on different yield criteria, and the results based on the proposed criterion had higher approximation to the experimental data. In addition, it was found that the geometry size of the pipeline and the strain-hardening exponent were the main factors that determine the burst pressure, and the pipeline with thicker wall or smaller diameter could bear more pressure. The results of this paper are significant to the design and evaluation of oil and gas pipelines.