Research On Structural Strength Characteristics Of Floating Offshore Wind Turbine Blades

On purpose of achieving the goal of "carbon peak and neutrality" in 2060,it is of crucial importance for China to harvest renewable and clean energy from ocean.Offshore wind energy is one of the most promising renewable and clean energy sources with both advantages and challenges.With the increasing power and complexity of wind turbines,the supportting platform of marine wind turbines has also been updating from fixed type to floating structure.The floating offshore wind turbine blades are subject to variable loading during their service life due to harsh marine environment and multi-degree freedom motions of floating platform,which makes it difficult to assess their structural strengths.Therefore,it is of great significance to study the structural strength characteristics of floating offshore wind turbine blades for ensuring the safety of wind turbines operation.In this thesis project,the structural strength of floating offshore wind turbine blades is studied based on finite element method and numerical analysis method.The structural strength of spar-type floating offshroe wind turbine blades under complexed load conditions is analyzed,and the influence of impact of ship on floating platform is considered.The structural strength characteristics of blades under maximum instantaneous acceleration are studied in depth.The main contents of this paper are as follows:1.Introduce the finite element method used in structural strength analysis of offshore floating wind turbine blades and the overall dynamic analysis technology of floating offshore wind turbine blades,analysis various loads on the blades and give the calculation methods for versatile loads.2.Taking the 5MW floating offshore wind turbine blade published by NREL as the reference blade.The composite material finite element model of the blade is established according to its aerodynamic and material characteristics,and the influence of the composite layer thickness on the stress distribution of the blade is evaluated.3.FAST software developed by NREL is used to carry out the overall dynamic analysis of the floating offshore wind turbine in order to obtain the aerodynamic load distribution of the blades.5MW floating offshore wind turbine on Spar platform is used as the calculation object in the overall dynamic simulation.The wind speed,aerodynamic load distribution of the blades,bending moment distribution of the blade roots and maximum tip deformation under different design loads are analyzed.4.Loading calculation of blade finite element model is carried out by using ABAQUS software,and structural stress of blade under typical load is analyzed.The correctness of finite element calculation model is determined by comparing the tip displacement of blade calculated by finite element model with that obtained in the numercial analysis by FAST.5.The structural strength characteristics of wind turbine blades in the collision schenarios between ship and floating offshore wind turbine support platform are studied.By applying maximum instantaneous acceleration to the blade roots in the finite element model,the structural strength characteristics of the blade structure in this scene are obtained,and the deformation and stress of the blades under combined hydrostatic conditions and wind and wave conditions are further analyzed.This paper mainly studies the structural strength characteristics of 5MW offshore floating wind turbine blades under complex marine loads,and the research outcomes are expected to show some good reference values for future design development and structural strength check of floating offshore wind turbine blades.