Impact force estimation and sound quality evaluation in the random impact on a thin-walled structure

Abstract

The noise generated by random impacts on the thin-walled structure which has a rectangular convex is estimated. The identification of impact force is important for the estimation of impact noise. Many researches on impact force dealt with only single and vertical impact and did not deal with the randomness for impactor’s material, shape, mass, impact velocity, position and angle. In this research, the method to estimate the time history of impact force from the impact conditions is proposed. The relationship between the impact conditions and the time history of impact force is investigated by the striking experiments using a rigid pendulum with a force sensor attached at the tip of pendulum. According to the result, it is found that the time history of impact force depends on only impactor’s mass and impact velocity while other conditions are not affected. Then, the time history is approximated with the extreme function and use the empirical formula for the relationship between the impactor’s mass, the impact velocity, and the coefficient in the extreme function. For an example of thin-walled structures, the noise generated by random impacts on the thin plate having a rectangular convex is estimated using the approximate vibration analysis and the estimated impact force. The estimated noise agrees almost well with the measured noise. Moreover, the sound quality is evaluated by sharpness and the relationship between sound quality of random impact noise and design specifications like convex position and shape.