Experiments on shock-absorbing capacity of granular matter under impact load

Granular matter is a complex energy dissipation system. The friction and the viscous contacts among particles can dissipate effectively the system energy caused by external impact load. The force chain structure in granular system can extend the local impact in spatial dimension and expand the instantaneous impact in temporal dimension, thus to obtain the effective shock-absorbing effect. To investigate the absorbing capacity of granular matter under an impact load, in the present study, we develop an experimental system, in which a rock ball impacts granular matter in a cylinder under gravity, and the impact force on the cylinder bottom is measured with three load cells. The influences of particle size, material propery, thickness of granular matter on shock-absorbing capacity are discussed. The results show that irregular particles have more shock absorbing capacity, while the large-size particles have a slightly higher shock absorbing capability than the small-size particles. The thickness of granular matter, H, is a key parameter to affect the shock-absorbing. Critical thickness, H-c, is obtained in the experiments. The shock-absorbing capacity of granular matter is enhanced with H increasing when H < H-c, while H has little influence on shock-absorbing when H > H-c. The resutls above are obtained with constant impact energy. Critical thickness H-c should be a function of impact energy and will be determined in the next study. With the experiments on shock-absorbing capacity of granular matter, it can reveal basic mechanical behaviors of granular materials and be applied in mechanical vibration absorptions.