Estimation of the impact noise from coated plates

Abstract

While driving a car on a road, noise from the collision of gravels rolled up by the tires makes a driver uncomfortable. The underside of the car may be coated with a damping layer on the steel plate to reduce noise. To estimate the effect of the damping layer on noise, the time history of the impact force is experimentally measured with an impact apparatus with a rigid pendulum and a force sensor which hits a coated rectangular plate. The impact force is then formulated as an approximate function with parameters of impactor’s mass and velocity. By using the approximate function of impact force, the vibration and sound pressure radiating from coated plate are estimated based on the Rayleigh-Ritz method where the coated plate is assumed as a pure plate with mechanical properties synthesized with those of damping layer and steel base plate. The estimated sound pressure agrees very well with the measured one. The effects of material and thickness of coated plates on the impact noise are revealed with the estimation.