Mixed mode dynamic crack-fiber bundle interaction using caustics

Caustic method was extended to study the interaction between the mixed mode dynamic matrix crack and the fiber bundle in fiber reinforced composites. First, the dynamic caustic experiments were conducted using transparent specimens with different thicknesses of fiber bundles under dynamic three point bending load. Then, the evolutions of dynamic shadow spots at the crack tip shielded by different thicknesses of fiber bundles were obtained. Moreover, the dynamic stress intensity factors were extracted from the shadow spots. Finally, the crack propagation and bifurcation behaviors were analyzed. It was shown that the stress intensity factors and crack propagation velocities were shielded by the fiber bundles, and the shielding effect increased with the increase of fiber bundle thickness.