Effects of Specimen Configuration on Tensile Fracture Mechanism of Unidirectional CFRP

Monotonic tensile tests were carried out on unidirectional CFRP to clarify the effects of specimen configuration on fracture mode and tensile strength. Three types of specimen configuration, a standard specimen according to JIS, necked-on-width specimen and necked-on-thickness specimen having various thicknesses of the necked region, were used. The following results were obtained. (i) A transition in fracture mode from tensile failure at the necked region (fracture mode type A) to interlaminar shear failure spreading to the outside of the necked region before final fracture (fracture mode type B) was observed in the necked-on thickness specimen as the thickness ratio of necked and un-necked regions increased. Fracture mode type A occurred when the ratio was low because the tensile failure load was lower than the shear failure load, and high thickness ratio resulted in fracture mode type B due to increasing tensile failure load over that of the shear. (ii) The specimen which fractured with shear failure exhibited lower tensile strength than the specimen which fractured in the tensile mode at the necked region.