Relation Between the Shape of Impact End and Generated Impact Force

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In designs for machine parts or structures to stand an impact loading, it is fundamentally important to know the outlines of the dynamic deformation at the contact part and of the impact force generated at that part. In a collision of machine parts or structures with each other or a collision of a flying object against a structure, the impact ranges usually from a few meters per second to tens of meter per second. Even if the impact speed is a few meters per second, an inelastic deformation or a crush may sometimes be produced at the contact part. This, therefore, makes the impact-end condition very complicated.Tanimura(1983) has devised a new, simple method which allows the impact force generated at the contact part to be measured directly. The technique u ilized a special sensing plate which was designed to deliver the equivalent effect to a sensing wall, as if small strain gages were embedded in the solid. Using the method, the dynamic plastic behavior and the impact force generated at a contact part were studied through the experiments in which various sizes of aluminum bars, whose ends were of a variety of shapes of truncated cones, collided against the sensing plate at various speed up to 11 m/s.Theoretical expressions have also been derived by which the impact force generated at the contact part can be predicted fairly well, for the both cases when a bar colliding is comparatively short and so the effect of wave propagation in the bar can be ignored, and when a bar colliding is comparatively long and the wave propagation effect can not be ignored. By comparing the theoretical curves with the measured impact force-time records, the effectiveness of the derived theoretical expressions has been confirmed.