Abstract
The mechanical degradation of several [0,90,0] fibre reinforced cross ply composite materials has been investigated under both wet and dry conditions. The tensile characteristics of the material have been determined in air, and their resistance to corrosion by various acidic and basic solutions assessed. Particular attention has been focussed on the geometry of the laminate, the nature of the fibre/matrix interface, and the post-cure temperature. A computer programme has been developed which predicts the occurrence and location of the first crack in the transverse ply, and subsequent cracking sequences. The inherent thermal strains were found to have a detrimental influence on the durability of the laminates under both dry tensile and corrosive environments. This effect could be enhanced by either an increase in post-cure temperature, an increase in the transverse ply thickness, or a local concentration of glass fibres. A significant improvement in both dry and wet performance was observed when laminates were prepared with discrete transverse tows of fibre. A number of different types of fibre reinforcement have been incorporated into the laminate coupons to determine the role of the fibre/matrix interface. The coating on the fibre was found to regulate the corrosion process indicating that the debonding occurs at the fibre coating/matrix interface. Some evidence suggested that good fibre/matrix adhesion could improve the dry tensile performance. The effect of several corrosive environments on the stress corrosion of single E-glass filaments has been evaluated and compared with the corrosion resistance of the laminates which they reinforce. The nucleation of damage in laminates did not correlate with single filament failure times which implied that damage nucleation in the laminates was more dependent upon the solubility of the glass degradation products.