THE EFFECTS OF CRUSHING SPEED ON THE ENERGY-ABSORPTION CAPABILITY OF COMPOSITE TUBES

The energy-absorption capability as a function of crushing speed was determined for Thornel 300-Fiberite 934 (Gr-E) and Kevlar-49-Fiberite 934 (K-E) composite material. Circular cross section tube specimens were crushed at speeds ranging from 0.01 m/sec to 12 m/sec. Ply orientations of the tube specimens were [0/ +/- THETA]2 and [+/- THETA]2 where THETA = 15, 45, and 75 degrees. Based upon the results of these tests the energy-absorption capability of Gr-E and K-E was determined to be a function of crushing speed. The magnitude of the effects of crushing speed on energy-absorption capability was determined to be a function of the mechanisms that control the crushing process. The effects of crushing speed on the energy-absorption capability is related to whether the mechanical response of the crushing mechanism that controls the crushing process is a function of strain rate. Energy-absorption capability of Gr-E and K-E tubes ranged between 0 and 35 percent and 20 and 45 percent, respectively depending upon ply orientation. The crushing modes based upon exterior appearance of the crushed tubes were unchanged as a result of changing crushing speed for either material. However, the interlaminar crushing behavior of the Gr-E specimens changed with crushing speed.