Paper number 872

STRAIN RATE EFFECTS ON THE STRENGTH OF SOME GLASS-FIBRE REINFORCED POLYMER COMPOSITES

M.Z. Shah Khan, M. Taylor, C.R. Townsend and I. Grabovac

DSTO Aeronautical and Maritime Research Laboratory
PO BOX 4331, Melbourne, Victoria, 3001, Australia

Summary

The sensitivity to increasing compressive strain rates was measured in terms of the maximum strength of glass-fibre reinforced composites (GRP). Strain rates from quasi-static level (0.005s-1) to intermediate level (10s-1) were achieved on a servo hydraulic test machine, and high strain rates (in excess of 1000s-1) were achieved using a Hopkinson bar. The strength of the woven GRP composite, when tested in the in-plane direction, depended on the mechanism of deformation and failure. Strength levels were higher when deformation occurred uniformly over the specimen geometry while delamination type failure resulted in lower strength levels. The strain rate effects in the normal direction (through-thickness loading) showed the strength increased by 20% between strain rates of 0.1s-1 and 11.0s-1 and this was followed by a 20% decrease at high strain rates. The maximum strength of the short fibre composites were found to be sensitive to increasing compressive strain rate. The maximum strength was also found to be affected by the difference in resin systems. The composite with polyester resin was significantly stronger higher strength at all strain rates than the composite with vinylester resin. Post failure examination showed greater wetting and adhesion between glass fibres and polyester resin than between the same glass fibres and vinylester resin.

Keywords

naval composites, mechanical properties, strain rates, fracture behaviour.