衝突の衝撃荷重に及ぼす多重反射応力波の影響 （アンビルを介しての棒と球の間接衝突）

Abstract

The free end of an anvil which is in contact with a sphere undergoes the normal collinear impact by traveling bar. If the length of the anvil is small, several wave reflections may occur in the anvil. In this paper, the impact load of sphere caused by the reflected waves was theoretically analyzed by a wave equation and the Hertz's contact theory.Since it is difficult to theoretically evaluate the reflection coefficient of wave at the discontinuous section where the anvil and the sphere are in contact, it was experimentally determined by observing the reflected wave passing through the anvil by a strain gage method. The particle velocity due to reflected wave was related to the load which the anvil transmits into the sphere. When the reflected wave arrives at the end of anvil before the load of sphere arisen by the former wave reaches the maximum value, impact load should be evaluated by using the particle velocity added to the first. On the other hand, when the reflected wave comes after the maximum value of load, the next particle velocity only affects the load transmitted into the sphere. When the circular cylinder with hemisphere end was used in place of the sphere in the experiment, the impact behavior depends only on the curvature of hemisphere and not on the shape of other part, because the ratio of length to diameter of the cylinder was not so large. As the number of repetitions of reflected wave increased, the maximum value of impact load grew up, but the acting period of force decreased. The analytical results of impact load were in agreement with the experiments.