High Strain-Rate Behavior of Plain-Weave S-2 Glass/Vinyl Ester Composites

Abstract

Thick-section composites made from plain-weave S-2 glass fabric (24 oz./sq. yard) and vinyl ester (411-C50) resin have been tested over a wide range of strain-rates (200-1600 s -1) using a compression split Hopkinson pressure bar (SHPB) with a momentum trapping device. Experiments were performed in two material directions: thickness and fill. Three different types of specimens having rectangular cross sections were tested with thickness ranging from 3.8 mm to 12.7 mm. The strain-rate effects on maximum stresses and maximum non-linear strains have been characterized. The dominant failure modes of the material have been determined through optical and scanning electron microscopy (OM and SEM). It has been identified that the dynamic ultimate stress and failure strain is higher than the corresponding quasi-static values. The ultimate stress is found rate insensitive for both thickness and fill direction loading. The non-linear failure strain is also found to be rate insensitive in the case of thickness direction loading; however, the failure strain increases with strain-rate in the case of fill direction loading. The dominant dynamic failure modes in thickness direction loading are compressive matrix cracking, fiber breakage, and lateral flow of fiber bundles. In the fill direction loading, the dynamic failure modes are kink band formation, delamination, transverse matrix cracking, and longitudinal splitting.