The study on structure design of fender of offshore wind turbine based on fractal feature during collision with ship

The number of construction offshore wind turbines (OWTs) is gradually increasing with high clean energy demand and low technology costs. During their service life, a large number of ships will inevitably collide with OWTs, which results in collapse load acting on the OWT foundation. This paper proposes a novel fender for the OWT exposed to extreme collision using the fractal structure, as the first step toward protecting the safety of the OWT structure. The proposed the fractal structure is based by the cartesian circle, which defined by tangent circle theorem, applied to ring protection design. The paper investigates the anti-collision performance of fractal structure fender on the simulated response of the tripod OWT installed in the coastal waters by comparing tradition and fractal structure. Furthermore, the difference of external diameter and different orders are discussed under the collision actions, which are implemented in the LS-DYNA. The results show that with the increase of the order of fractal pores, structure of the first-order fractal pores is good for the fender to absorb enough collision energy and the anti-collision performance of fender increases by the greater mass.