Investigation of dynamic mode I matrix crack-fiber bundle interaction in composites using caustics

In this work, the dynamic mode I matrix crack-fiber bundle interaction was studied using caustics. First, the strain fields at the dynamic mode I matrix crack tip ahead of the fiber bundles were deduced using transformation toughening theory. Subsequently, the caustic equation at mode I dynamic matrix crack tip ahead of the fiber bundles was established to investigate the influences of the fiber bundle and the crack propagating velocity on the initial curves and caustic curves at the dynamic matrix crack tip. Finally, a series of dynamic caustic spots surrounding the propagating crack tip were recorded using optical caustic experiment, and dynamic stress intensity factor were extracted from the shadow spots.