EFFECTS OF STACKING SEQUENCES ON MECHANICALLY FASTENED JOINT STRENGTHIN QUASI-ISOTROPIC CARBON-EPOXY LAMINATES

The desire to develop adequate strength, particularly at bolt hole, te nds to restrict the choice of fiber patterns to those that do not devi ate very far from a quasi-isotropic pattern. The weakest parts of a co mposite structure are the joint parts; therefore, the effective stacki ng sequences on joint strength while maintaining the isotropic nature have to be cleared. In this study, the effect of stacking sequences on quasi-isotropic T300/2500 joint strength was examined. Two joint geom etries that exhibited bearing failure and net-tension failure under pi n-bearing loads were chosen. Six types of laminate configurations were examined in quasi-isotropic patterns. According to observation failur e mode and acoustic emission (AE) measurement, the evidence of the eff ect of stacking sequences was made clear. The highest bearing and net- tension strength obtained from the quasi-isotropic laminates tested al l had 0 degrees plies on the outer surfaces, 90 degrees plies next to the 0 degrees plies, and +/-45 degrees plies interspersed in the middl e of the laminate [0 degrees(2)/90 degrees(2)(+45 degrees/-45 degrees) (2)]s.