Fatigue damage analysis of the deepwater riser from VIV using pseudo-excitation method

• The fatigue damage of a deepwater riser from in-line and cross-flow VIV is studied using PEM.
• The DVM is used to calculate the vibration of 2D cylindrical strip in uniform flow.
• The FVM is employed for evaluating the structure dynamics.
• The in-line VIV is suggested to be considered in the design stage of riser.
• PEM is proved to be efficient and accurate to estimate the fatigue damage of a deepwater riser.

The fatigue damage of a long deepwater riser undergoing in-line and cross-flow vortex-induced vibration (VIV) in deepwater is numerically studied using pseudo-excitation method (PEM) in present paper. For evaluating the fluid–structure interaction problem of vortex-induced vibration of deepwater riser at high Reynolds number, the strip theory is employed in this paper, and the discrete vortex method (DVM) is used to calculate the VIV of each strip to obtain the load spectrum as the pseudo-excitation, while the finite volume method (FVM) is employed to evaluate the structure dynamics of a deepwater riser. The VIV is considered as a stationary random process. The response of riser to vortex induced excitation is calculated using pseudo-excitation method. The DVM model and pseudo-excitation method are both validated by comparing their numerical results with experiments. The fatigue damage of one deepwater riser is evaluated based on the Palmgren–Miner Rule.