Finite element prediction of the ultimate collapse strength of casings

Abstract

Accurately predicting the ultimate collapse strength is very important for casing design. For an infinitely long thick-walled casing under external pressure, a finite element method (FEM) model has been proposed to obtain a better understanding of the ultimate collapse strength of a casing. A very careful comparison with a series of experimental data has been conducted to verify the accuracy and reliability of the proposed FEM model. In addition, the predicted post-collapse behaviour compares well with the experimental test data. The validation proves that, if the material behaviour and imperfection variables are known, the ultimate collapse strength can be predicted to a satisfactory degree of accuracy. The major factors that affect the ultimate collapse strength of a casing have been fully investigated using the proposed FEM model.