Finite Element Analysis of the ILSS of Graphite Fiber/Epoxy Composites -Effects of High Energy Radiation and Boundary Conditions-

유한 요소법을 이용한 Graphite Fiber/Epoxy 복합재료의 ILSS 해석 -고에너지 방사선과 경계조건의 영향-

In an effort to understand the interiaminar shear strength(ILSS) of composite materials, the stress concentration factor of laminas along the length of model composites has been calculated by Losing the finite element method(FEM) . The model composite is notched on both sides and it is unsupported as well as supported by a fixture. The results from the finite element analysis show that the stress distribution is not changed by the loading mode. The stress concentration factor is shown to be independent of the magnitude of applied stress. The maximum shear stress occurs at the inner side of the notch tip where the fracture is expected to be initiated from. The stress concentration increases with the radiation dose up to 10,000 Mrads for both the unsupported case and the supported one. However, the stress concentration is much higher in the unsuppoed rase than in the supported case. The rate of increase in the stress concentration factor with radiation is consideably higher in the unsupported case than in the supported case. An equation developed from Kaelble's theory and the calculations by FEM suggests that the interfacial bond strength should be increased by radiation. The equation explains why the ILSS for the unsupported case is lower than that for the supported case and why its curve has a maximum. The predicted maximum point is not exact but not far apart from the experimental value.