Lectotype Optimization And Fatigue Analysis For Offshore Wind Turbine Foundation Structure

Offshore wind energy is one of the most attractive sources of renewable energy.During the last decade,offshore wind turbines were extensive application throughout Europe,but the economics of offshore wind turbines especially foundations are currently challenges,so the development of quite economical foundation structure becomes the important topic in the offshore wind turbine research.Selecting a reasonable foundation type is the first important step in the optimization design of offshore wind turbine foundations.Considered the fuzzy characteristic of many affect factors and based on the multi-objective fuzzy optimum theory,a fuzzy optimum lectotype and evaluation method of offshore wind turbine foundations is proposed in this paper.The principle, model and the application steps of this method are given.In order to decrease the subjectivity of some evaluation factors,the non-structural fuzzy decision method and the prior relation method are also introduced to determine membership function and the weigh factors.Through the application of the above method in an offshore wind turbine foundation project,it can be known that the proposed method in this paper is feasible and useful.Take the structure gross weight as the objective function,take intensity,rigidity,stability and geometry restraint as constraints,by the use of ANSYS parametric design language (APDL),establishing the three-dimensional finite element analysis model of foundations for offshore wind turbines and the multi-design rules and multi-constrained conditions of the optimization design model,and on the base of this analysis,the optimization design aims to minimize materials is carried out.On the base of the optimization design,the simplified fatigue analysis approach and the spectrum analysis method are used for the fatigue analysis to the offshore wind turbine tripod foundation structures and estimates its life.The computed result indicated that the using of simplified fatigue analysis approach can be able to meet the demands of the allowable peak hot spot stress;Under the design wave in the article,the platform's approximate life is 53 years. The results prove that the methods and technical solutions presented in this thesis are practicable and sianificative.Based on the obtained simulation results,it appears that this new method can provide an advantageous reference for users encased in structural designand security evaluation of an offshore platform.