Viscoelastic effects on the interlaminar fracture behaviour of thermoplastic matrix composites .2. Rate and temperature dependence in unidirectional peek/carbon-fibre laminate

The interlaminar fracture roughness of a unidirectional poly(ether ether ketone)/carbon-fibre laminate and the toughness of the plain resin have been studied over a wide range of temperatures and crack speeds by double cantilever beam (DCB) and double torsion (DT) testing, respectively. Temperature shift factors obtained in tension and plane-strain compression on unnotched samples of the plain resin have been used to reduce the fracture data to a single reference temperature, and master curves of strain-energy release rate, G(Ic), versus crack speed, ii have been derived. The results indicate that the toughness of both materials is strongly rate sensitive, especially in the range of low crack speeds and/or high temperatures, and no significant difference in the toughness values between unreinforced resin and composite was found. The results have been discussed in comparison with those reported in the literature on the same material and with data presented in a previous paper on a poly(ether imide)/carbon-fibre composite. (C) 1996 Elsevier Science Limited