Effect of thickness on the damage tolerance of glass/epoxy laminates subject to repeated impacts

To evaluate the influence of layer and laminate thickness on the repeated impact response of E-glass/epoxy laminates, two types of cross-ply stacking sequences ([0/90]3n and [03/903]n), with two different thicknesses (4 mm and 8 mm), were analyzed. The investigation, led by running quasi-static perforation tests and repeated impact tests, outlined the better performance of [03/903]n laminates. Experimental results were analyzed through a macroscopic damage variable (damage index DI) and by microscopic observation and digitalized profiles of impacted specimens. The higher damage tolerance of [03/903]n laminates was found to depend on the capability of spreading the damage over a more extended area and of tolerating a higher permanent deflection. For both laminate types, the end of the steady damage accumulation phase was observed to correspond to through-thickness transverse cracking.