A theoretical analysis on the failure of unpressurized and pressurized pipelines

Abstract

A theoretical quasi-static analysis is proposed to predict the response and the onset of failure for pipelines. The maximum strain criterion, the effect of strain rate and an empirical formula for estimating the length of a plastic hinge are employed in the analysis. This theoretical study allows the local or denting deformation to continue during the global deformation phase. A good agreement has been achieved between the theoretical predictions and the corresponding experimental results for the threshold value of the impact energy and the maximum permanent transverse deflection for both unpressurized and pressurized pipelines. It transpires that both the maximum strain criterion and the empirical formula for the hinge length are applicable in the theoretical analysis. With a simple computer program, the theory can be used to predict the failure of pipelines. Discussions are made for the influence of internal pressure on the shape of the indentation and the threshold value of the impact energy.