The effect of fibre volume fraction on the onset of fracture in laminar materials with an array of coplanar interface cracks

The onset of fracture process in a layered composite with coplanar interface cracks under compression along layers is studied within the scope of 3-D theory of stability using the model of piecewise-homogeneous medium. Each layer consists of a matrix reinforced by continuous parallel fibres and is modelled by a compressible, linear elastic, transversely isotropic material. The eigenvalue problem with respect to the controlled parameters, namely, the crack length, the crack spacing and the 0°-plies layer volume fraction is solved for the shear and the extensional modes utilizing the finite element analysis by commercially available FE code. The results are obtained for 0°-plies volume fraction V_0° = 0.1 ... 0.9 for the typical dispositions of cracks. The effect of the crack length, the crack spacing and the 0°-plies volume fraction on the critical microbuckling strain in the composite was determined.