Transverse Compressive Behaviour of Carbon-Epoxy Laminates and Its Influence onContact Laws

摘要

The transverse compressive behavior of two kinds of laminates with differentstackings, unidirectional and crossply, was investigated in order to obtain their elastic constants and compressive fracture properties. The data were intended to determine the deviation from Hertz's contact law. Furthermore, the contact between a spherical steel indentor and a plane surface of carbon reinforced plastic laminate was studied for the two different trackings with two different radii of the indentor, R = 5 and R = 7.5 mm. A simple theoretical model for Young's modulus in the z direction and Poisson's ratio in the x, z and y, z directions for cross ply laminate is also developed. The transversal Young's modulus of crossply laminate is shown to be much higher than that of a single ply, due to the constraint imposed by the adjacent layers in the laminate. The values predicted by the contact law were compared to the experimental data and generally found to agree well as long as the applied loads are not too great. However, in the cases of a crossply specimen, the power of the contact law seems to be lower than that of the experimentally obtained curves. This can be compensated not only by changing the exponent of the original law but also by adding terms of higher order. The correlation between failure pressures in uniaxial compression and fractures in indentation is poor.