Droplet 평판충돌에 의한 차량루프부의 소음방사 메커니즘

Abstract

Rainfall noises are caused by collision between droplets and surface of panels. The noises have unique characteristics and provide a certain perception of sound. The rainfall noise on roofs of vehicles, however, can be felt to be uncomfortable because the vehicles have a limited internal space. In this study, experiments were conducted to find out mechanism of rainfall noises. Analytical models were proposed to predict characteristics of the noises. A droplet shape on impact with surface of panels was taken using a high-speed camera. In addition, waveforms of noises and vibrations and forces of the panel were measured at the same time. Characteristics of the waveforms changed according to time were compared to the results of high-speed recording. As a result, a correlation with the characteristics of noises and droplet shape after collision were identified through individual droplet tests. A wave analysis model was proposed to find out causes of the correlation between the shape and the noise. The noise characteristics of the vehicle caused by impacts of the droplets were predicted through the proposed model.