TRANSVERSE CRACKING AND DELAMINATION INTERACTION IN THE FAILURE PROCESS OF COMPOSITE LAMINATES

The transverse crack (TC) failure and delamination of a composite laminate with an outer 90 degree layer is studied. The stress field near each TC enforces a saturation value for their density and limits the stiffness reduction of the 90 degree layer for the TC failure mechanism. The failure pattern near a TC, observed by experiments, is found to be similar to a contour map of equal maximum stresses near the tip. A global statistical analysis for the TC accumulation and delamination growth is introduced and the results are compared to experimental data. From the stress field near a delamination crack it is concluded that the delamination process followed by the TCs may be due to dynamic effects. Regular fracture mechanics tools for the prediction of the failure process are limited, since the peeling stress singularity region is too small to be included in the homogeneous continuum mechanics range.