Effect of thickness on indentation response and tensile loading behaviour of glass/epoxy laminates under acoustic emission monitoring

Abstract

ABSTRACT This research work investigates the effect of thickness on the quasi-static indentation and tensile loading behaviour of glass/epoxy laminates. Cross-ply [0°/90°]3S laminates fabricated at different process pressures (40 kg/cm2, 50 kg/cm2 and 60 kg/cm2) were subjected to quasi-static indentation loading. Furthermore, the residual load-bearing capacity was estimated by performing tensile after indentation (TAI) test. The damage development and corresponding failure mechanisms associated during loading were characterised by acoustic emission monitoring. The results show that the damage onset load, residual dent and damage area were dependent on the thickness of the laminates. Type II samples (processed at 50 kg/cm2) exhibited higher damage onset load and contact stiffness by an average of 20% and 25% than type I and type III laminates. Higher peak force, reduced damage area and permanent dent were attributed to greater elastic response. In contrast, Type I samples (processed at 40 kg/cm2) with thick resin-rich zone exhibited severe delamination through transverse shear cracking. This observation was also evident from the intense AE signals related to debonding/delamination modes, which correlates well with the damage area.