The object of this note is to present the results of an investigation conducted to determine the interlaminar shear strength of a carbon fibre composite material under high rates of loading. Because of the fact that significant viscoelastic and creep effects can occur in the shear loading of composite materials, it was anticipated that rate effects might be important in interlaminar shear tests.The interlaminar shear test has been used on many types of composite. References 1 and 2 treat the effect of specimen geometry and non-uniformity of shear stress, whilst References 3 and 4 show the effects of fibre volume fraction, void content, span-to-depth ratio and roller diameter on apparent interlaminar shear strength. It is shown that all these variables can be significant in testing a given material.The standard interlaminar shear (ILS) test takes about 30-60 seconds to produce interlaminar shear cracks. During the impact of birds onto composite fan blades in a turbofan engine, interlaminar shear cracks may occur in a fraction of a millisecond. The occurrence of such cracks does not necessarily imply incipient failure, especially in suitably reinforced blades. Nevertheless, it is necessary to know what bird size will lead to initiation of damage and the interlaminar shear strength must thus be determined under more realistic impact conditions.
MATERIALThe material used was Hyfill carbon fibre (28 X 106 Lb/in2 modulus) in HR4C epoxy resin [6]. Three plates, two unidirectional and one 0-90° crossplied, were produced from unidirectional pre-impregnated fibre with dimensions 8.5 X 4.0 X 0.3 inches. Each plate contained thirty plies and was moulded for 60 minutes at 165°C followed by 16 hours postcuring at 180°C. Estimated fibre content was 60%. Specimens with dimensions 2.0 X 0.3 X 0.3 inches were cut from each plate. 1 Registered trademark for carbon reinforced resin.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.