Shock-pulse transmission on driving metal tubes into the ground

Abstract

Analysis of the energy distribution in the transmission of a shock pulse to a metal tube through an intermediate element shows that the efficiency coefficient kef, the ratio of the energy in the head of the transmitted pulse to the impact energy, depends on parameters such as the mass and rigidity of the intermediate elements, the magnitude of the added mass, and the tube rigidity. If a circular plate is used as the intermediate element, then kef increases with increase in plate thickness until it is 0.2 of the tube diameter. Further increase in the plate thickness leads to increase in energy dissipation uncompensated by reduction in the striker recoil coefficient. The presence of an added mass reduces kef, on account of increase in both the energy dissipation and the recoil of the striker. Increasing the tube rigidity — for example, by increasing its cross-sectional area — reduces the efficiency of shockpulse transmission as a result of increase in the striker recoil coefficient and increase in the proportion of energy in the oscillating tail of the elastic pulse. It remains to thank E. N. Sher for useful discussions of the experimental results.