Evaluation of residual strength in fiber reinforced composites subjected to impact using acoustic emission test

This paper investigates the relation between acoustic emission events and the corresponding behavior of the specimens after damage under tensile loading. Tensile strengths of carbon/glass fiber epoxy composites subjected to impact damage were evaluated experimentally. The variations of amplitude, energy, and dominant frequencies of the AE events were studied to investigate the post-impact behavior of specimens. Different layers (6, 12-ply) and fiber materials were assessed, and their effects were considered. Waveform patterns and frequency domain analyses were also utilized to evaluate the damage severity. This practical method can be used as an advanced and straightforward approach to estimate either the value of the damage or residual strength subsequent to impact in laminated composites. It was proved that the impact damage led to dropping residual strength, especially in carbon/epoxy specimens, since they are sensitive to impact.