Geometric and Loading Rate Effects on the Energy Absorption of Triaxially Braided Carbon Vinyl Ester Tubes

摘要

Triaxially braided carbon vinyl ester composite tubes of a range of fibre orientations, (0°/±30°, 0°/±45° and 0°/±60), and tube wall thickness (2mm, 3mm and 4mm) have been investigated under axial loading conditions. Testing has been carried out quasi-statically and also, dynamically at 5 and 7.2m/s using an instrumented dropped weight testing machine. In addition, in order to further characterise and understand the energy absorbing mechanisms, in-plane testing has been performed on flat plaque test specimens using custom designed test fixtures. The axial tows were seen to dominate the energy absorption effects and the angles of the bias tows were seen to have a relatively small effect. Tubes of greater wall thickness were found to exhibit higher specific energy absorption levels as a result of a more well-constrained crush zone morphology. Specific energy absorption was found to decrease slightly with test speed due to increased matrix damage seen at the impact rates. In-plane coupon tests showed that tensile and compressive strengths and elastic moduli were increased at the dynamic loading rates. The in-plane characteristics were seen to correlate well with peak stresses and initial stiffnesses seen in the tubes.