FRACTOGRAPHY OF FRACTURE IN CFRP UNDER COMPRESSIVE LOAD

The mechanical properties of the fiber/resin interphase affect both th e macroscopic mechanical properties of the composite material and thos e of the fiber and resin. Interfacial properties are therefore very im portant for mechanical design. Carbon-fiber-reinforced plastics (CFRP) commonly have a laminated structure, and the fracture mechanism in CF RP is a complex problem. Fractography is well known to be a useful tec hnique for elucidation of the fracture process. In this paper, axial c ompressive tests were carried out on unidirectional laminated CFRP. Th e car bon fibers used in this report were of the PAN-based high-streng th type and the pitch-based high-modulus type, and were subjected to v arious degrees of surface treatment. In this paper the degree of elect rical charge is revealed. The effect of surface treatment on the fract ure process in these CFRP was examined by scanning electron microscope . As a conclusion, flexural fracture of the reinforcements is mainly c aused by delamination of the fiber/resin interphase, and improvement o f the interphase by surface treatment could control the flexural fract ure of reinforcements. (C) 1997 Published by Elsevier Science Limited.