Compressive Strength Retention of Impact-Damaged Laminates Containing Particulate Fillers

The effect of six particulate fillers on the compressive strength of undamaged and damaged glass-epoxy laminates was studied. The intention was to determine whether, and how, the mechanical properties of the filled organic matrix could be correlated with the impact damage tolerance (expressed as compressive strength retention after impact) of fitted epoxy-glass laminates. Impact damage was induced by an instrumented falling weight device. The laminates contained solid glass beads, hollow glass microspheres, quartz, calcium carbonate, alumina trihydrate (ATH) and mica. The test results showed that all the fillers, apart from hollow glass microspheres, increased the tensile and flexural moduli of the fitted epoxy, and this in turn was accompanied by an improvement in the compressive strength of some of the undamaged lominates, but there was no positive correlation between the flexural modulus of the fitted matrix and the impact damage tolerance as reflected in compressive strength retention. In contrast there was a good correlation with matrix strength; i.e. a significant decrease in the compressive strength retention of impact-damaged laminates as the matrix flexural strengths were reduced by adding fillers. The pre-impact interlaminar shear strength of the laminates also correlated well with the compressive strength retention after impact.