5. Conclusions
The strain rate effect of the luffa sponge material was investigated in this paper by conducting experiments at different strain rates on cylindrical specimens of the luffa sponge with a wide range of density. The mechanical properties of the luffa sponge material at various strain rates were obtained at the macroscopic level. The following conclusions can be drawn from our investigations.
(1) Compressive strength, plateau stress and specific energy absorption of luffa sponge material are all sensitive to the rate of loading;
(2) Empirical formulae are obtained for compressive strength, densification strain and specific energy absorption at various strain rates at the macroscopic level;
(3) The dynamic enhancement for compressive strength is more prominent than that for the plateau stress. The underlying mechanism can be explained by the type II structure response of luffa fibres;
(4) The energy absorption capacity per unit mass at high strain rates of luffa sponge is higher than that of many commonly used metallic foams;
(5) Luffa sponge has the potential to be used as an alternative sustainable material for various engineering applications such as packaging, acoustic and vibration isolation, and impact energy absorption.