Fatigue Analysis of Deep-Water Risers under Vortex-Induced Vibration Considering Parametric Excitations

This paper presents vortex-induced vibration (VIV) and fatigue analysis of deep-water risers in shear flow considering parametric excitations due to the heave of floating platform. As a first step, the governing equation of transverse motion of the riser is established; the dynamic response of the riser is calculated numerically by the finite difference method based on Van der Pol wake-oscillator model. Then the fatigue damage of the riser is obtained by applying Miner cumulative damage theory and S-N curve. The results show that the VIV response of the riser, especially in the flow with low speed, is much larger due to the parametric excitation. The bending stress and the fatigue damage at the bottom of the riser are significantly increased under parametric excitations.