ROLE OF MATRIX RESIN ON FRACTURE STRENGTHS OF UNIDIRECTIONAL CFRP

As a common feature of composite materials, prominent anisotropy in mechanical properties is observed in unidirectional carbon fiber reinforced plastic (CFRP), which has higher fracture strength and stiffness along the carbon fiber strengthening component. Since it is well known that a resin matrix exhibits characteristic time and temperature dependence on mechanical behavior, that is, viscoelastic behavior, the CFRP is expected to exhibit similar behavior. Based on the above mentioned hypothesis, the fracture strength of unidirectional CFRP was investigated for various directions and modes of loading over wide ranges of temperature and strain rate, in conjunction with similar investigations on the epoxy resin matrix. Furthermore, the role of the matrix resin on fracture strengths of uinidirectional CFRP is discussed on the basis of SEM observations of the fracture surface.