Mode I Fracture Toughness of Unidirectional Composites

Tiris paper investigates Mode I fracture touglmess of carbon fiber, carbon laminate, and combined carbon fiber-fiber glass. Total of twelve tensile tests (four sample of each) are performed to measuremode I fracture touglmess. Two of these samples are one inch wide with a 0.02 inch (0.5 mm) crack on one side of each strip, and the other two are two inches wide with a 0.04 inch (1.0 mm) crack on one side of each strip. Hence, the ratio between the crack length and width of the member are equal. The mode of failure is appeared approximately along the fiber layers. Three additional tests are preformedon the same materials, except the fibers are confined along the wide of the samples; however, the final results are almost the same.