A sensing-plate method for measuring force and duration of impact in elastic-plastic impact of bodies

A new method for measuring an impulsive force generated at the impact end in collision and the duration of impact is developed. The measurement method is based on a simple structure, here called the special sensing plate, which produces the same effect as strain gages embedded in a solid. The sensing-plate method is confirmed by calibration tests to be effective for measuring not only the impulsive force generated at the impact end of a body but also the duration of the force. The measurement is almost entirely free from disturbance caused by interference from reflected waves. Plastic impact experiments are also performed for pure aluminum bars with several different lengths by impacting them on a sensing circular plate. Impact specimens are shot out from a high-pressure air gun. The time variation of stress at the impact end of the specimen bars colliding with the sensing plate and the duration of impact are measured at various impact velocities. The strain-rate dependent theory of plastic wave propagation is applied to obtain a theoretical prediction of those results. The theoretical predictions have shown to agree well with the observed results. Paper was presented at the 1988 SEM Spring Conference on Experimental Mechanics held in Portland, OR on June 5–10.