Transverse cracking and delamination in composite materials

Abstract

An experimental investigation has been conducted on damage behaviour related with matrix cracking under static and fatigue loading using two stacking sequences of the (0/90_n/±45)_s and (0/±45/90_n)_s laminates for n = 1, 3, and 6. The latter stacking sequence produces tensile interlaminar normal stress along free edges of a tensile coupon, whereas the other stacking sequence produces compression at the same edges. Emphasis in this study was on the interaction between transverse cracks and delamination, and effect of layer thickness on crack density and propagation. Transverse crack and delamination were periodically measured by interrupting testing until final failure. Experimental results indicate that the crack density and propagation are influenced by layer thickness, and delamination appears to be mainly governed by either, or a combination of, tensile interlaminar normal stress and size of transverse crack. The applied force at incipient delamination can be predicted by an existing theory with a certain limitation.