Application of Onset Theory to Onset of Transverse Cracking in Fabric Composites

Abstract

A paper presented at ICCM-19 included a methodology for application of Onset Theory to the prediction of microcracking in the transverse plies of orthogonal [0/90] fabric laminates. This paper applies the methodology to predict damage locations and laminate strains for failure of plain weave fabric specimens manufactured from two material systems – HTS40/RTM6 and T300/CYCOM970. The laminate strains are first dehomogenised to define local strains in the tow architecture of the fabric. This is achieved using meso-mechanical unit cell analysis in which the resin and tows are modelled as continua. For a selection of predefined critical locations in the tow bundles, the strains are further dehomogenised using an identical procedure as the one defined for the uni-directional specimens in the previous applications. The influence of matrix plasticity and temperature dependent mechanical and thermal properties of the RTM6 resin are applied in the dehomogenisation procedure. The Onset theory predictions for damage locations were compared to those obtained from microscopic surveys of partially failed plain weave fabric specimens.