Toughening behavior of unidirectional fiber reinforced composites containing a crack-like flaw: Matrix crack without fiber break

The Mode-I stress intensity factors of unidirectional fiber reinforced composites are studied based on the framework of linear elastic fracture mechanics. As one of the dominant damage mechanisms, a matrix crack in the absence of fiber break is considered here. The bridging of crack faces is assumed a principal toughening mechanism in the unidirectional fibrous composites. Based on a frictional shear–slip relationship, the effect of fiber-bridging mechanism is reflected as the toughening mechanism of unidirectional fibrous composites. On computational scheme, Newton’s method is adopted to solve the governing simultaneous equations for the fiber-bridging stresses and the crack mouth opening displacements. By making use of the proposed computational framework, a series of parametric studies is carried out to examine the effects of key material parameters upon the toughening of fibrous composites in a systematic manner.