Energy Absorption in Composite Structures

The specific energy absorbed during the axial collapse of a variety of graphite, Kevlar and glass fiber composite tubes was determined. Although structural collapse occurred by a fracture failure mode, the specific energy absorption was higher than that of high strength metal tubes which col lapsed by buckling, over a wide range of tube geometries (t/D ratios), provided that the correct trigger mechanism was used to initiate the failure. Little change in the specific energy absorption was observed over a wide range of compression rates or with temperature changes below 20°C; above 20°C the effect of temperature varied with the resin employed. Collapse occurred initially by interlamellar shear followed by fiber fracture. The results were correlated on the basis of the specific interlamellar shear stress which permitted the energy absorption values for a variety of materials to be compared.