EFFECT OF TRANSVERSE MATRIX CRACKS ON THE FREQUENCIES OF UNSYMMETRICAL, CROSS-PLY LAMINATES

The effect of matrix cracks on the eigenfrequencies of unsymmetrical, cross-ply laminates is investigated. The cracks are modelled as aligned slit cracks across the ply thickness and transverse to the laminate plane. The distribution of cracks is assumed statistically homogeneous for a given average crack density. The results are given for antisymmetrically and unsymmetrically laminated plates. The effect of reduction in the laminate stiffness is studied by plotting the ratio of the fundamental and higher order frequencies of cracked and uncracked laminates against the aspect ratio, crack density and relative layer thicknesses. It is observed that the amount of reduction in the vibration frequencies is substantially less than the reduction in the affected elastic moduli of the material.