Robust Passive Vibration Control of Monopile Offshore Wind Turbines Using a Single-Sided Vibro-Impact Nonlinear Energy Sink Under Wind–Wave–Seismic Loading

Monopile offshore wind turbines are vulnerable to excessive vibration under coupled wind, wave, and seismic loading because of their slender and flexible structural characteristics. This study investigates a single-sided vibro-impact nonlinear energy sink (SSVI NES) installed inside the nacelle of a 5 MW monopile offshore wind turbine. A reduced-order ten-degree-of-freedom dynamic model is established using the Euler–Lagrange formulation, and turbulent wind, irregular wave, and seismic inputs are generated using TurbSim, the Kaimal and JONSWAP spectra, the Morison equation, and 15 PEER ground motions. The proposed controller is compared with an optimized tuned mass damper (TMD) under nominal and frequency-detuned conditions. The results show that the SSVI NES achieves vibration reduction comparable to that of the optimized TMD under the design condition while requiring a smaller absorber stroke. More importantly, it retains its control effectiveness more stably under frequency detuning, indicating improved robustness against structural-frequency variations. These findings suggest that the SSVI NES is a promising passive solution for enhancing the operational safety and multi-hazard resilience of monopile offshore wind turbines.