Impact-fatigue behaviour of unidirectional carbon fibre reinforced polyetherimide (PEI) composites

Impact fatigue properties of unidirectional carbon fibre-reinforced polyetherimide (PEI) composites was evaluated by subjecting standard izod impact samples to low velocity impact loading at energy levels ranging 0.16-1.08 J by using Ceast Model Resil 25, a pendulum type instrumented impact test system. The effect of the previous low velocity impacts on the impact properties of the laminates was investigated. On the other hand materials were subjected to repeated low velocity impact tests up to fracture. Results of repeated impact study are reported in terms of peak load, absorbed energy and number of impacts. Fractographic analysis revealed the fracture by primary debonding, with fibre breakage and pullout in the tensile zone, but a shear fracture of fibre bundles in the compressive zone of the specimen.