Dynamic Analysis For Ply Structure Of Wind Turbine Composite Blade

Wind turbine blades, as the core component of the wind turbine, cost accout for20%~30%of all wind turbines. The application of composite materials in wind turbine isultimately applied on the blades. Uni-Directional reinforced of Glass and Carbon have theadvantages of low density and hight reliability of structure etc, which perform better thanthe steel currently used for wind turbine blades. So they have been more popular in theapplication of blades of medium-and large-scale wind turbines. Many domestic andforeign scholars are working on how to balance aerodynamic performance and structureperformance better on the blades. Thus, based on the rapid speed modeling of the windturbine blade, considering lay-up angle of fibeir of the composite laminates, this study isresearched and analyzed the influence on structure dynamic characteristic. This thesisdetailed as follows:(1) Based on BEM theory, considering the loss of blade tip and hub at the same time,this paper calculates axial inducible factors and circumferential inducible factors of eachsection of the blade element. They are the keys for the wind turbine to design blade withbetter aerodynamic shape. The original coordinates of airfoils can be easily transformed tospace coordinates by MATLAB. And then, According to APDL programming method, thepaper establishes finite element model rapidly.(2) Based on Classical Lamination Theory, the paper analyzed the relationshipbetween the elastic modulus of composite laminates and the lay-up angle of fibeir of thecomposite laminates, and deduced the Equivalent Property Method, which providetheoretical support and basis for the subsequent dynamic analysis.(3) According to different composite lay-up thickness and lay-up sequence of windturbine blade, this paper offers Lay-up Patterns of the different regions, Shear Web andSpar Cap. In this paper, by the stress stiffening effect for the blade, the dynamic models ofblade were analyzed and compared in two kinds of material property assignment ways, andanalyzed the relationships between different lay-up angles and rotational speeds andnatural frequencies of blade in detail. The results contrasted related literatures and themanufacturers, and were roughly the same standard of blade nature frequency, compared tothe former, first-order frequencies differ by3.8%, while compared to the latter, first-orderfrequency is6.87%, and draw a conclusion that it was right about the of the design andanalysis of blade. Campbell diagram was drawed, and which checked resonance conditionfor preliminary design blade intuitively, the results show the blade is safe and reliable. (4) By Fluid-solid interaction (FSI), we can get a transient wind pressure distributionof the blade accurately. The pressure distribution obtained from the flow analysis wasapplied to carry out static analysis. The result of static analysis was set as an initial loadingcondition and buckling analysis was conducted. The modal frequency of the blade isnarrowed by4.67%, the result proves that the fluid is ability to decrease the stress anddeformation by the stress stiffening effect for the blade.