FUNDAMENTAL RESEARCH ON IMPACT RESPONSE AND IMPACT SOUND GENERATION OF BRIDGE SLABS

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(a) IMPACT RESPONSE AND GENERATION OF IMPACT SOUND OF PLATES DUE TO COLLING BODYThis report presents the impact response of rectangular Mindlin plates subjected to colliding of a steel ball by using the eigenfunction expansion method and the Hertz's law of contact. The effects of impact force, contact time and material properties on the generation mechanism of impact response and the characteristics of propagation of flexural waves have been investigated. It is seen that the initial impact response of steel plates and wooden plates subjected to a colliding steel ball shows some different mechanism on the wave propagation. Beside the difference of mechanism of impact response generation, the sound pressure calculated by the present method on the assumption of plane wave shows good agreement of the acoustically experimental result.(b) RADIATION MECHANISM AND TIMBRE OF IMPACT SOUND OF PLATES DUE TO COLLING BODYImpact response and radiation of impact sound generated from bridge slabs and its joints under the action of moving vehicles have been one of the environmental noise problems. In view of troublesome nature of impact sound, several authors reported a series of studies on impact noise. However, attention was given to the radiation of residual sound after the impact of a body and a plate. In this report, the radiation mechanism and timbre of impact sound generated from plates subjected to colliding spherical bodies by the acoustic experiment are investigated. The effects of geometric and material properties of plates and spherical bodies on frequency spectrogram of sound pressure have been clarified, and the correlation between frequencies of vibrating plates and impact sound caused from plates due to colliding spherical bodies are also investigated.