Crushing Characteristics of Composite Tubes with "Near-Elliptical" Cross Sections

Abstract

An experimental investigation was conducted to determine whether the energy-absorption capability of near-elliptical cross-section composite tubular specimens is a function of included angle. Each half of the near-elliptical cross-section tube is a seg ment of a circle. The included angle is the angle created by radial lines extending from the center of the circular segment to the ends of the circular segment. Graphite- and Kevlar- reinforced epoxy material was used to fabricate specimens. Tube ply orientation was [±45] N where the number of ±45 pairs was 2, 4, 6, and 12. Tube internal diameters were 2.54, 3.81, and 7.62 cm, and included angles were 180, 160, 135, 115, and 90 degrees. Based upon the test results from these tubes, energy-absorption capability increased between 10 and 30 percent as included angle decreased between 180 and 90 degrees for the materials evaluated. Energy-absorption capability was a decreasing nonlinear function of the ratio of tube internal diameter to wall thickness.