Effect of fiber orientation on the energy absorption capability of carbon fiber PEEK composite tubes

Previous research works identified the effects of cooling rate, testing speed and tube geometry on the energy absorption behavior of carbon fiber reinforced polyether-ether-ketone (carbon/PEEK) composite tubes. One of the objectives of this work is to optimize the energy absorption capability of these tubes by changing the fiber orientation. Composite tubes with fiber orientations 0 degrees, +/-5 degrees, +/-10 degrees, +/-15 degrees, +/-20 degrees, +/-25 degrees and +/-30 degrees with respect to the axis of the tube have been investigated. The energy absorption capability as well as the crush zone morphology were dependent on the fiber orientation. Efforts have been made to relate the variations of specific energy to the changes in the crush zone morphology. Tubes with +/-15 degrees fiber orientation displayed a specific energy of 225 kJ/kg, the highest ever reported in the literature. The fracture mechanisms that resulted in the superior energy absorption performance of these tubes have been identified.