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The dynamic response of glass fibre-vinylester composite beams is measured by impacting the beams at mid-span with metal foam projectiles. The beams exist in composite monolithic form, and in sandwich configuration with composite facesheets and a core made from PVC foam or end-grain balsa wood. High-speed photography is used to measure the transient transverse deflection of the beams and to record the dynamic modes of deformation and failure. For both monolithic and sandwich configurations, a flexural wave travels from the impact site towards the supports. Ultimate failure of the monolithic and sandwich beams is by tensile tearing of the faces. The sandwich beams also exhibit cracking of the core, and facesheet delamination. The dynamic strength of the beams is quantified by the maximum transient transverse deflection at mid-span of the beams as a function of projectile momentum. It is demonstrated that sandwich beams can outperform monolithic beams of equal mass. The trade-off between core strength and core thickness is such that a low density PVC foam core outperforms a higher density PVC foam core. End-grain balsa wood has a superior stiffness and strength to that of PVC foam in compression and in shear. Consequently, sandwich beams with a balsa core outperform beams with a PVC foam core for projectiles of low momentum. The order reverses at high values of projectile momentum: the sandwich beams with a balsa wood core fail prematurely in longitudinal shear by splitting along the grain.

Quasi-static and dynamic experiments are conducted to characterise the mechanical response of a syntactic foam comprising hollow glass microballoons in a polyurethane matrix. Stress versus strain histories are measured in uniaxial tension and compression as well as in pure shear, at strain rates ranging from quasi-static in-situ tests are conducted to visualise the deformation mechanisms in tension and compression. The material displays a pronounced sensitivity to the imposed strain rate and relatively high tensile and shear ductility at both low and high strain rates. A tension/compression asymmetry is displayed in quasi-static tests but is lost at high rates of strain.