A RANDOM CRITICAL-CORE THEORY OF MICRODAMAGE IN INTERPLY HYBRID COMPOSITES .2. ULTIMATE FAILURE

This paper discusses the ultimate-failure behaviour of interply hybrid composites consisting of one layer of low-elongation fibre/epoxy sand wiched between two or more layers of high-elongation fibre/epoxy under uniaxial tension. A modified shear-lag model was first proposed for s olving the stress redistributions resulting from both failure of some layers and breakage of fibres in the high-elongation layers. The rando m critical-core probability model was then adapted for the statistical analysis of the ultimate-failure process in hybrids, and the ineffect ive length required in this study was obtained by using a simple limit analysis. The predictions of the ultimate-failure strain of hybrids w ere compared with the existing experimental results, and reasonable ag reement was obtained.