Abstract
In this paper, discussion is focused on the mechanical modelling of fiber bridging which affects the resistance of opening-mode crack extension parallel to fibers in unidirectional fiber-reinforced composites. Firstly, the formation process of a bridging fiber is considered and a model of this single fiber bridging is made to characterize precisely the behavior of bridging fibers under crack opening. By using this model, the forces acting on crack surfaces through a bridging fiber are estimated and the relationship between crack opening displacement and equivalent cohesive stress due to large number of bridging fibers is obtained. An attempt is made to derive equations which describe the crack extension with the cohesive stress acting on crack surfaces. By solving numerically these equations, the crack extension behavior is simulated. The simulated result shows agreement with the experimental result of a unidirectional glass fiber-reinforced epoxy composite.
It is concluded that the fiber bridging discussed here accounts for the opening-mode crack extension behavior parallel to fibers in the unidirectional fiber-reinforced composites.
