Steel elbow response under strong cyclic loading

Abstract

The present study examines the behavior of steel pipeline elbows subjected to strong cyclic loading conditions. A set of experiments is conducted where in-plane cyclic bending with constant amplitude is applied on the elbow specimens by controlling the elbow enddisplacements, resulting in failure within the low-cycle-fatigue range. The experimental work is supported by finite element analysis using detailed numerical models that take into account geometrical and material nonlinearities. Cyclic plasticity related phenomena are accounted for with the use of advanced plasticity models focusing on the localized concentration of deformations at the critical positions where cracking is likely to take place. Finally, the experimental/FE results are compared with analytical elastic/plastic solution. The experimental results are used to develop a low-cycle-fatigue curve in the framework of the strain-based fatigue design concept. Copyright © 2012 by the International Society of Offshore and Polar Engineers (ISOPE).