An analysis of the impact response of a composite beam

The impact response of a series of IM6 6376 carbon fibre composite beams was examined using a fully-instrumented drop-weight impact rig. A piezo-electric load cell and a newly-developed laser-light displacement transducer were used to determine the load-deflection histories of a number of centrally-loaded multi-directional composite beams. The impact response of the targets was then compared with the predictions offered by the solution to the dynamic equation of motion of an isotropic beam. The suitability of the model was further assessed by undertaking a limited number of tests on glass fibre-reinforced and Kevlar fibre-reinforced epoxy beams. A comparison between the experimental and predicted data indicated that agreement was good over the wide range of impact loading conditions examined. Distinct dynamic effects were noted when the length of the composite beam was significantly greater than the support span, suggesting that care has to be taken when using simple coupons to represent the impact response of more representative components. The properties of the GFRP and KFRP composites were found to be rate dependent with the dynamic flexural stiffness being up to 60% greater than the static value. It was shown that the response of these composites could also be modelled if this increase in stiffness properties was taken into account.