Experimental investigation of low-velocity impact characteristics of sandwich composites

Abstract

This study presents the results of an experimental investigation concerning the low-velocity impact response of sandwich composites. Impact tests were conducted to characterize the type and extent of the damage observed in a variety of sandwich configurations with graphite/epoxy face sheets and foam or honeycomb cores. Correlation of the residual indentation and cross-sectional views of the impacted specimens provide a criterion for the extent of the damage. In the foam-core samples, significant damage was found to be present for residual indentations over 0.13 mm. Although the high-density foam-core and thicker face sheet increased the amount of energy required to generate damage, the damage was still similar for similar levels of residual indentation. For the honeycomb samples, 0.25 mm of residual indentation indicated significant levels of internal damage. However, the surfaces of both the honeycomb and foam samples revealed very little damage at these levels of impact energy. As the impact energy was increased, the samples experienced one of two types of damage: a tear or crack from the center of the laminate to the edge, or significant damage consisting of a dent localized in the region of impact.