Behaviour of luffa sponge material under dynamic loading

Luffa sponge is a light-weight natural material which 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. The strain rate effect is an important material property for such applications. In the present study, compressive tests at different strain rates on luffa sponge material were conducted over a wide density range from 24 to 64 kg m−3. A photographic technique was applied to measure the sectional area which has an irregular shape. The stress-strain curves of luffa sponge material at various strain rates were calculated based on this measurement. When the dynamic data are compared with those of quasi-static experiments, it is found that the compressive strength, plateau stress and specific energy absorption of the luffa sponge material are all sensitive to the rate of loading. It is also found that the dynamic enhancement for the compressive strength was more prominent than that for the plateau stress. The underlying mechanism was discussed and clarified. Empirical formulae were proposed for the macroscopic strength, densification strain and specific energy absorption at various strain rates. A comparison study shows that the luffa sponge has better energy absorption capacity per unit mass than other cellular materials with similar plateau stress at various strain rates.