Dynamic strength properties of nano-composites:correcting dispersion effects

Dynamic material characterization is a fundamental issue in structural analysis and the main apparatus used to perform dynamic material tests is the so called Split Hopkinson Pressure Bar, SHPB. This device is based on the propagation of elastic waves in long bars. Due to lateral inertia, the waves traveling in the bars change their shape, which causes some errors on the evaluation of the stress-strain-strain rate in the tested sample. In this article one examines the influence of the correction of such effect on experimental data measured when testing a composite material. The material is a S2-glass/epoxy with nanoclays that were impregnated in the matrix for strength enhancement. Experimental data are discussed in the light of the dispersion correction, showing that such a procedure is an important aspect for a correct representation of the composite strength properties.