Co-authors​ :

 Ahn SUNG JIN (KOREA, REPUBLIC OF), Park HYUNBUM (KOREA, REPUBLIC OF) 

One of the damage to composite materials, the void, is a damage that often occurs in Resin Transfer Molding (RTM). The wind turbine blades is manufactured using RTM method. In this study, it is to predict how the void, which is a damage that occurs during the manufacturing process of the blade, affects the performance of the manufactured composite blade. The area of the void was predicted through micro and mesoscale analysis. The reduced physical properties were predicted by randomly arranging voids in the virtual specimen and conducting simulation using the homogenized physical properties. The composite material specimen is quasi-isotropic and laminated in [45/0/-45/90]2S and analyzed two experiments, ATSM D3039 and ASTM D6641, through the commercial program Digimat. The study classified and analyzed two cases, and gradually increased them, depending on the speed at which the fiber is impregnated. In addition, according to the rate at which the fiber is impregnated, it was classified and analyzed into intervoid formed between laminate at a slow speed and intravoid formed on the fiber at a high speed. In the study according to the void size, the tensile strength showed a greater change than the compressive strength, and when the void fraction was 5%, the compressive strength was analyzed to show a decrease of more than 40% compared to the case without pores. The stiffness is very insignificant compared to the strength, but it tends to decrease as the pore size increases, and the tensile stiffness is more sensitive than the compressive stiffness. A study on the change in physical properties according to the void fraction was conducted by fixing the void size at 200 μm. In the case of inter void, the maximum feasible porosity is 2%, and in the case of intra void, it is up to 7%. As a result of the analysis, in both cases of intra void and inter void, the tensile strength and compressive strength decreased as the void fraction increased. The tendency of strength loss was similar in tensile and compression, and in the case of stiffness, it was confirmed that the tensile stiffness was greatly affected by both the intra case and the inter voice case. In this study, the knock down factor was found and utilized by analyzing the results to reduce the error of the physical properties predicted by the program. Through this, the goal of this study is to analyze the deterioration of physical properties due to manufacturing defects in wind blades produced in the future and predict the resulting lifespan and operational capacity.