Computation of plastic collapse capacity of 2D ring with random pitting corrosion defect

Abstract

This paper is aimed at assessing the effects of local random pitting corrosions on the collapse pressure of a 2D ring under external pressure. A Python program was used in combination with the FE code ABAQUS to solve the FE model. Firstly, a series of non-linear FE analysis of rings were carried out to study the influence of such random pitting factors, as diameter-to-depth ratio, distribution form, and pitting number. This indicated that the mass loss and maximum pitting depth were the main factors that govern the collapse pressure of 2D ring. A high-order buckling mode was found with higher collapsed pressure under specific combination of random pitting corrosion factors, which turned out to be the snap-through of archer beam. Finally, a closed form formula able to predict the collapse pressure of a 2D ring with 2-wave form out-of-roundness and random pitting defects was established by nonlinear regression analysis of FE results with consideration of mass loss, maximum pitting depth, diameter-to- thickness ratio (D/t) as well as out-of-roundness (△).