A NUMERICAL STUDY OF THE COMPRESSION AND SHEAR FAILURE OF WOVEN CARBON-CARBON LAMINATES

A finite element analysis was performed to determine the influence of microstructural inhomogeneities on the compressive and shear strength of 2-D carbon-carbon laminates. In particular, the effects of amplitud e and distribution of the fiber bundle crimps, and lengths and distrib ution of the interply and transverse bundle cracks are determined. The results of the numerical study are successfully compared with experim ental observations made in an earlier study under compression and shea r loading. Under a warp-aligned compression load, the local material p arameter which controls the overall instability in the form of multipl e interply delaminations is the critical energy release rate for growt h of pre-existing interply cracks, except for when the maximum length of these cracks is less than 0.6 mm when the failure is through bundle kink-induced shear faulting. For all pre-existing crack lengths, the same parameter was responsible for initiating a planar shear fault fol lowing the crimp boundaries under an interlaminar shear loading. Accor dingly, the numerical cell-model considered here conforms to the above mechanism by allowing the participation of the energy release rate as the failure parameter.