Estimation Method of Transverse Strength of Uni-Directional Composites Considering the Random Arrangement of Filaments
Yuzo FUJITA and Tetsusei KURASHIKI
Abstract:A procedure to estimate transverse strength of unidirectional composite is proposed in this study. Most of the micro structure of fiber reinforced plastic is unidirectional composite. The estimation of the transverse strength of unidirectional composite is very important because damages in FRP originate from the transverse crack. As the method to estimate the strength of unidirectional composite, theoretical methods and experimental methods have been applied. However, the transverse strength is influenced by several factors such as the volume fraction of fiber, interfacial strength, and residual thermal stresses. In order to estimate the transverse strength considering the factors, we propose an FE method in this study. Firstly, FE model of unidirectional composite considering the random arrangement of filaments are generated. Interfacial elements are installed between filaments and resin to simulate the interfacial behavior. The damage conditions such as damage criterion and strength of resin and interface are determined by comparing the static transverse tensile test of single-filament embedded specimen and FEM. The transverse strength is estimated by FE analysis based on damage mechanics considering the effects of residual thermal stresses. Several FE models with volume fraction of fiber of 40%, 50% and 60% have been generated respectively and the strengths have been estimated. As the results, the strength decreased when the volume fraction of fiber increases without considering residual thermal stresses. On the other hand, it is clear that the strength is dependent on the random arrangement of filament strongly with considering the residual stress. Key Words:Fiber reinforced plastic, Damage mechanics, Unidirectional composite, Random arrangement, FEM