Experimental investigation on the effect of glass fiber orientation on impact damage resistance under cyclic indentation loading using AE monitoring

This paper investigates the effect of glass fibre orientation on the impact damage evolution and post-impact residual strength of glass/epoxy laminates, using mechanical and acoustic emission (AE) analysis. The glass fibre reinforced polymer (GFRP) composite laminates with stacking sequence such as 0°, 90°, [±45°] and [0°/90°] were tested. The indentation-induced damage behaviour was examined in GFRP composite laminates by conducting drop weight impact and quasi-static indentation (QSI) tests to induce barely visible impact damage (BVID). Both tests provided essentially the same results for damage modes, dent depth, back surface crack size and load-deflection history. Mechanical parameters such as peak force, incident energy, absorbed energy, rebound energy and linear stiffness were used for the quantification of the indentation response. The AE parameters, such as amplitude, rise time, counts and energy were considered for monitoring damage progression during QSI loading. Also, other parameters linked to AE monitoring, such as the rise angle (RA), Felicity ratio (FR) and sentry function (SF) were measured for evaluating damage progression in each cycle of indentation. These results showed the [±45°] laminates having higher indentation damage resistance compared to other fibre orientation, whereas residual compressive strength was high for 0° laminates.