FAILURE OF FIBER COMPOSITES - A LATTICE GREEN-FUNCTION MODEL

A new powerful numerical technique for investigating the failure of fi ber reinforced composites is presented. The technique utilizes 3D latt ice Green's functions to calculate load transfer from broken to unbrok en fibers, and also includes the important effects of fiber/matrix sli ding. The inherent flexibility of the technique in adjusting the spati al extent of load transfer allows for the study of many aspects of rea l composite failure processes which have been unobtainable to date. Us ing this technique, composite reliability, the influence of manufactur ing defects on performance, and the overall optimization of composite performance can all be investigated in detail. Initial results using t his approach show that load transfer and the existence of spatially-st aggered fiber breaks play an important role in determining strength an d toughness of composites. Furthermore, the critical configurations of fiber breaks that initiate catastrophic failure are complicated 3D ob jects and any single spatial plane is composed mainly of sliding fiber s rather than broken fibers, with a few strong fibers intact within th e critical defect.