A vortex-induced vibration model for the fatigue analysis of a marine drilling riser

Abstract

ABSTRACTThe objective is to propose a quick and accurate vortex-induced vibration (VIV) model to predict the fatigue life of marine drilling risers. The nonlinear wake oscillator model was applied to represent the lift force, which is described by a fourth-order partial differential equation set. Next, we adopted the generalised integral transform technique (GITT) to transform it into second-order ordinary differential equation system, which was solved by the Runge-Kutta method. Validation of the numerical model was implemented and a good agreement was achieved. Next, an S-N curve was adopted to conduct fatigue prediction. The results demonstrate that under the conditions set forth in this paper, an increase in the current and outer diameter could reduce fatigue life, except when the outer diameter reaches a certain value, at which point the tendency is reversed. Moreover, when the top tension coefficient reaches a certain value, the fatigue life tendency is also reversed.