Effects of Crush Failure Mode on Energy Absorption in Carbon/Epoxy Tubes

摘要

An investigation into the effect of cross sectional shape, trigger type, and crush speed is presented for IM7/8552 carbon/epoxy tubes. Three ply layups were designed so that their failure modes compared to the three broad classifications (fragmentation, splaying, and brittle fracture) observed in carbon fiber composite tube specimens during axial crushing. Composite tubes fabricated with each of these ply layups were tested with circular and square cross sections, bevel and tulip triggers, and at quasi-static and dynamic crush speeds. Results showed that circular cross sections were more efficient than square cross sections when comparing similar test variables. Tulip triggers were found to increase energy absorption, although only for certain failure modes and only at quasi-static crush speeds. Strain rate effects varied widely across cross sectional shape, layup, and trigger type. The differences in energy absorption values when comparing testing variables were attributed to changes in the failure mechanisms that occurred during crushing.