Dynamic response of an offshore wind turbine subject to ice loading in glacial tills

• Main Authors: Zou, Pengxu, Bricker, Jeremy, Fujisaki-Manome, Ayumi
• Format: Other/Unknown Material
• Language: unknown
• Published: Authorea, Inc. 2024
• Subjects: Ice Sheet
• Online Access: http://dx.doi.org/10.22541/au.170663811.10845601/v1

The impact of drifting ice load on offshore wind turbines (OWT) in ice-covered sea areas is a critical issue affecting their serviceability and safety. To gain a better understanding of the ice-induced vibrations (IIVs) and ice-structure-soil interactions (ISSIs) of OWTs, this study employs the cohesive element method (CEM) coupled with the finite element method (FEM) to simulate level ice sheet behavior. The study defines a stress and separation relationship for brittle and quasi-brittle materials and adopts an elasto-plastic constitutive law for bulk ice mass elements. Additionally, a Smoothed Particle Hydrodynamics (SPH) method that simulates level ice cover by mesh-free particles is also employed for comparison. Since soil-structure interaction (SSI) significantly impacts the dynamic response of OWTs under ice loading, the Mohr–Coulomb (M-C) model is selected for glacial soils. As a result, a three-dimensional numerical coupled ISSI model for dynamic response analysis of an OWT is developed and a case study of the ISSI of an OWT proposed in Lake Erie is presented. Moreover, a sensitivity analysis of the impacts of ice and wind loadings (e.g., ice thickness, ice drifting speed, wind speed, and ice-wind misalignment angle) on the dynamic response of the OWT is conducted. The results indicate that the coupled CEM-FEM approach is capable of analyzing ice-OWT interactions more effectively than the SPH method. Furthermore, the vibration frequencies of the OWT under combined ice-wind loads can coincide with the OWT’s inherent natural frequencies, causing severe response. The ice loading can have a more significant impact on the OWT’s foundation compared to wind loading. This study provides insights into and references for the ice-induced vibrations and ice-structure-soil interactions of offshore wind turbines in ice-covered coastal areas.