Study On Mechanical Properties Of Composite Rotating Anti-collision Device

As a renewable energy,offshore wind energy is the most large-scale commercial development of clean energy and has developed rapidly.With the construction of offshore wind turbine(OWT),collision accidents between ships and offshore wind power structures occur frequently in bad weather.Once an accident happens,it will not only cause property losses and casualties,but also cause environmental pollution such as oil leakage and marine ecological damage.Therefore,an effective anti-collision is designed and proposed,which has important engineering significance.In this paper,a composite rotating anti-collision device is designed based on the single pile foundation of OWT.In this paper,numerical simulation is used to study the dynamic performance of the device under different connection forms and initial rotation.The main work of this paper is as follows:(1)A multi-layer composite rotating anti-collision device made of fiberglass reinforced plastic(GFRP)and polyurethane foam(PUR)is proposed.The device can rotate by receiving water waves through wings during the coming of ships,so as to achieve better guiding effect and reduce the damage effect of ships on piles.(2)The ABAQUS software is used to carry out numerical simulation analysis of the rotatable and non-rotatable anti-collision device during the frontal and side collision of the ship.The crashworthiness of the anti-collision device is investigated from energy conversion,stress,strain,impact force,and movement process.The results show: At the end of the collision,the total kinetic energy of the system under rotatable conditions is greater,the total internal energy is smaller,and the ratio of total frictional energy to kinetic energy conversion is greater.Taking the initial offset of 2.0m as an example.At the end of the collision,the total kinetic energy under the rotatable condition is 1.57 times bigger than the total kinetic energy under the non-rotatable condition.And the total internal energy under the rotatable condition is 0.83 times small than that of the non-rotatable condition.Friction energy consumption under the rotatable condition is 3.01 times bigger than that of non-rotating conditions.During the collision,the collision force between the ship and the anti-collision device under rotatable conditions is smaller,and the maximum stress value of the single pile foundation of the offshore wind turbine under rotatable conditions is smaller.Taking the initial offset of 2.0m as an example,the maximum stress value of a single pile foundation of an offshore wind turbine under rotatable conditions is 0.89 times that of non-rotating conditions,and the maximum impact force under rotatable conditions is 0.89 times that of non-rotating conditions.Under rotatable conditions,the bow deflection distance before and after collision is larger,so it has a good guiding effect.Therefore,the anti-collision performance of the rotatable anti-collision device is superior.(3)The influence of the rotation speed of the composite anti-collision device on the anti-collision performance is further discussed.The study found that: with the increase in the rotation speed of the anti-collision device,the peak value of the internal energy and collision force of the single pile foundation gradually decreased and the damage range was smaller.The Z-axis offset distance of the ship increased.For example,when the initial rotation speed is 2.0rad/s,the peak internal energy of the single pile foundation of the offshore wind turbine during the entire collision process is reduced by 5.8%,the peak force of the collision of the ship against the collision avoidance device is reduced by 49 k N,and the ship's Z-direction offset distance is increased by 8.09% compared with the condition without initial speed.Therefore,compared with the anti-collision device without rotating speed,the rotating anti-collision device has better guidance and superior collision resistance.