EFFECT OF INTERLAYER MODULUS ON FRACTURE MODE RATIO FOR INTERLEAVED COMPOSITE LAMINATES

Results are presented from a study to assess the effect of the interla yer modulus on the energy release rate and fracture mode ratio in inte rleaved composite laminates. Two different geometries and material sys tems are studied. It is found that the fracture mode ratio is a very s trong function of the interlayer modulus, and that varying the interla yer modulus can Significantly change the percentage of opening mode wh ich occurs for a given remote loading. The significance of these resul ts is addressed with respect to choice of an interleaving system, as w ell as with respect to methodologies to eliminate computational diffic ulties associated with the oscillatory stress singularity in non-inter leaved composites.