Advanced beam model for fiber-bridging in unidirectional composite double-cantilever beam specimens

This work investigates the interlaminar fracture and fiber-bridging in double-cantilever beam specimens from the theoretical and experimental points of view. Crack initiation and propagation tests were performed on unidirectional E-glass/polyester double-cantilever beam specimens. The well-known classical beam theory-based solution agrees excellently with the experimental results in the case of crack initiation tests. In contrast, the classical model seems to be inadequate for the evaluation of the propagation test data. The apparent contradiction was attributed to the fiber-bridging phenomenon. Thus, a novel beam model was developed, which accounts for the effect of fiber-bridging. Based on the solution of beam theory, the number of the bridging fibers and the bridging force can be approximated. The former reaches a peak value and decreases notably, while the force tends to a plateau value as the crack grows.