FRACTURE-TOUGHNESS OF UNIDIRECTIONAL SHORT-FIBER REINFORCED EPOXY COMPOSITES

Consideration is given to achieving a feasible basis on which linear elastic fracture mechanics may be employed to measure toughness of short-fiber-reinforced composite materials. While the critical stress intensity factors may not entirely represent the fracture conditions on the boundary of the process zone at the crack tip, the modified Griffith criterion can be practically employed to assess the brittle fracture and splitting of these materials. Experiments performed on uniaxially oriented, short-glass-fiber/epoxy indicated that toughness is only slightly affected by fiber volume fraction or aspect ratio within the limits tested. When a crack is initiated perpendicular to the fibers, the strain energy release rate is nearly an order of magnitude higher than when a crack is initiated parallel to the fibers. © 1990.