Damage accumulation behavior of non-crimp fabric-reinforced epoxy composite under static and cyclic tensile loading

Abstract

A non-crimp fabric with a stacking sequence of [0°,+45°,90°,−45°] embedded in epoxy resin matrix was analyzed. Samples for mechanical test were obtained from laminates at different orientations depending on the textile architecture direction at 0°, 45°, and 90° in order to study the relationship between damage initiation and propagation with fabric geometry. Tension mode tests (static and cyclic) were carried out to evaluate the evolution of damage using as a main tool, the acoustic emission technique that allows monitoring the mechanical behavior of the materials during the test in ‘real time’. Results show that there is a remarkable mechanical influence of the reinforcement textile in the composite and that damage generation and progression (mechanisms of fracture) is highly dependent of the direction in which the stress is applied in relation with the architecture of the fabric. In static tensile mode, samples at 0° exhibited better mechanical parameters than samples at 90°, while at 45° orientation was lesser. The effect of textile geometry was demonstrated to have an influence in such mechanisms. In cyclic tensile mode, Kaiser effect is observed at low stresses, while the experimental results showed that the Felicity effect became clearer along with the increasing of stress level.