DYNAMIC STRESS-CONCENTRATION EFFECTS ON STRESS WAVES IN COMPOSITE MODELS WITH DIFFERENT FIBER-END GEOMETRIES

The stress-concentration effect of fiber-end geometries on the propagating stress waves in composite models was investigated by the dynamic photoelastic method. Aluminum fibers with rectangular, semicircular, v- and wedge-shape ends simulating such materials as reinforced concrete and fiber-bundle-reinforced composites were cast in epoxy resin to form the models. Impact was applied by the bullet of a rifle. The effects of the reinforced rod or fiber-bundle ends on the dynamic birefringent patterns were analyzed by comparing the fringe patterns at the same locations in a plain model of identical contour under the same loading conditions.