THE ROLE OF FIBER MORPHOLOGY ON THE CREEP-BEHAVIOR OF DISCONTINUOUS-FIBER-REINFORCED COMPOSITES

The role of the geometrical parameters of the fibers and effects of fiber distribution in the matrix on the creep deformation behavior of 20% discontinuous-fiber-reinforced composite were numerically investigated, including the debonding and fiber pull-out mechanisms. During the analyses, it is assumed that the matrix deforms with a power-law creep relationship and the fibers are rigid. The debonding behavior at the inter-face was simulated in terms of a cohesive zone model which describes the decohesion by both normal and tangential separation. The results indicate that, for a given fiber geometry and distribution parameters in the matrix, an increase in the interfacial strength or an increase in the work of separation per unit area of interface reduces the creep rates. For even very weak interface characteristics, it is possible to achieve lower creep rates and delayed interface failure by suitable selection of the geometrical parameters of fibers and by controlling the distribution of fibers in the matrix. The role of applied stress direction and formation of a more ductile phase between the fibers and the matrix in the overall creep behavior were also elucidated.