Validation of a 3-Dimensional Finite Element Analysis Model of Deep Water Steel Tube Umbilical in Combined Tension and Cyclic Bending

This paper focuses upon validation of the 3-D FEA model for cyclic bending under tension load case. An important aspect of accurately modelling the behaviour is the complex stick, partial slip and full slip behaviour of the internal components. Particular attention is paid to the resisting moment resulting from internal friction, known as the friction moment. The effect of increasing tension on the friction moment is studied. The kinematics of sliding are compared to analytical models developed for helically wound structures, such as flexible pipes, and show a very good correlation that confirms the accuracy of the model. Also, the mean axial strain of the steel tubes due to the friction induced by this sliding is highlighted. The hysteretic curves of the axial strain in steel tubes subjected to cyclic bending under tension are derived and validated against full scale experimental data.