Energy absorption of truncated Kevlar epoxy cones under off-axis loads

Abstract

A total of 27 Kevlar/epoxy truncated cones was manufactured and crushed under off-axis loads. Side loads were introduced by cutting the cones at angles relative to their central axes. The failure modes were observed, and the specific sustained crushing stresses were determined and compared against graphite/epoxy cones of the same lay-up and similar geometry. The Kevlar/epoxy cones exhibited significantly different failure modes than the graphite/epoxy cones. Specifically, the cones did not experience brittle fracture, and thus maintained structural integrity after crushing. The Kevlar/epoxy cones were less sensitive to the angle of the applied load than similar graphite/epoxy cones; however, the energy absorbed per unit mass is significantly lower. The role of specimen taper and load inclination is different than that for graphite/epoxy cones. In particular, 10° tapered cones overall had the best performance even under uniaxial loading conditions.