Abstract

Carbon fibre composite materials with high temperature bismaleimide resin systems as the matrix component are currently being used on structures for both military and civilian aircraft. A major concern with these materials is the effect of long-term exposure to service environments on their physical and mechanical properties. A carbon fibre reinforced bismaleimide composite was evaluated to determine the effect of fibre type and exposure to a high temperature environment on its interlaminar-shear strength and impact performance. Interlaminar shear and Charpy notched impact specimens were prepared, aged for certain periods of time at three different temperatures in air-circulating ovens and tested. The results reflected the degradation of matrix and the fibre-matrix interface with ageing, accordingly the interlaminar-shear strength deteriorated progressively and the failure mode of the impact specimens changed from a brittle failure in the unaged state to a progressive delamination in the aged state. Change in the impact failure modes influenced the energy dissipation characteristics of the specimens.