Breakage of Beaded Fibers in a Polymer Matrix

Abstract

Intermittent beading is a promising design strategy that enables simultaneous improvement of strength and toughness of fiber-reinforced composites. Despite the potential for amplification in mechanical properties, the failure mechanisms of beaded fiber composites are not fully understood. In this study, calculations are carried out for the breakage of beaded fibers in the polymer matrix composites. The plastic deformation of the polymer matrix and debonding of the bead–matrix, fiber–bead, and fiber–matrix interfaces are accounted for in the numerical analyses. It is found that the location of fiber break is governed by the toughness of the fiber–bead interface and fiber strength. The low toughness of fiber–bead interface promotes the emergence of break inside bead, and high fiber strength is capable of activating break outside bead. The break at the edge of bead prevails in most cases. We have further revealed that the fiber–matrix interface with high strength and enhanced toughness can give rise to large amount of fiber breaks, while low degree of fiber cracking emerges in the case of strong fiber–bead interface. For the bead–matrix interface, the intermediate interfacial strength generates a high degree of fiber breaks and low interfacial toughness suppresses fiber cracking, leading to small amount of fiber breaks. In addition, the dependence of plastic dissipation in the polymer matrix on fiber breakage is elucidated.