Research On The Progressive Damage Mechanisn Of Wind Turbine Blade Composites Structure Based On Multiscale Analysis

Composite materials are widely applied in aviation,aerospace,navigation,transportation,wind power and other fields for the advantages of high specific strength,large modulus,good fatigue resistance,corrosion resistance and design ability.They are especially suitable for structural design with the limitation of lower weight and higher strength.Due to the complicated micro-structure and the high heterogeneity of composites,the mechanical properties of the material and the damage evolution of the structure have a great correlation with the microstructure.Compared with the traditional metal material,the composites have more various damage models like fiber/matrix break,debonding and etc.The failure evolution is complicated,therewith,The multiscale analysis is proposed to study on the physical fields on macro and micro scale of composites,as well as the damage evolution.In order to solve the problem about studying on the properties and damage evolution on composites material,the beginning of study is to establish the quantitative relationship between the microstructure and macro-mechanical properties,therewith,the damage variable is introduced into the microstructure.This model is applied to studying on damage evolution in components material and crack evolution in structure.The specific research is listed above:At first,this thesis proposed a multiscale modeling method.The High-fidelity Generalized Method of Cells(HFGMC)is applied to study on micromechanical of composites with period microstructure,the theory is verified with finite element micromechanical theory.The scanning microscope technique is applied to obtain the repeated cell which represents the micromechanical of composites.The repeated cell domain is dived into several subcell domains with HFGMC.Then,the homogenization theory is used to solve the average response of the repeater cell.The micromechanical model is established,combined with a laminate classic theory for modeling lamina level and finite element theory for modeling laminates level,the multiscale model of composites is established.Then,this paper proposed a progressive damage model which is applied to research on the damage evolution and crack of laminates.Based on the HFGMC theory,this paper develope a micromechanical model with damage evolution by applying the failure criterion and damage evolution model into subcells.The nonlinear behavior of resin is also studied based on the Schapery theory.This model is applied to calculate the initial strength and final strength of single lamina.The implement of the multiscale damage analysis for composites structure by further development of ANSYS/LS-DYNA.The ANSYS/LSDYNA is used to establish the finite element model of macrostructure,the LS-DYNA provide the interface to compile the user-defined material model subroutine.Based on the method,this thesis study on the micro and macrophysical fields of composites laminate under transverse tensile,revealing the damage and crack evolution.For verifying the theory,the strain gages are applied to measure the strains of the surface.The wind turbine blades are the most important component of the wind power equipment.The turbine blades are supplemented by the severe environment,which is prone to cause the crack or even break,causing the serious accident.Therefore,the safety of wind turbine blades has become a hot research.In this thesis,fiber Bragg grating sensors are applied to the monitor the strains of wind turbine blade composite materials.The validity of the progressive damage model is verified by comparing the prediction results with the experimental results.The microdamage evolution of the composites structure is predicted with numerical method.This work has important theoretical value and engineering significance for the long-life safety operation of the blade composite material structure.