Vibration and scattering monitoring of Japanese roofing tile by accelerometer

A series of wind tunnel tests were conducted on the vibration and scattering behavior of full-size models of tiles widely used as roofing materials on Japanese wooden dwellings. This study has investigated the nature and source of such movement with the aim of providing better insight into the mechanism. The roofing tiles were set up on a pitched roof in the downstream flow from a wind tunnel. Vibration of the tiles was measured by using the Laser Doppler Vibrometry and an accelerometer, while the practical natural frequencies of the roofing tiles were analyzed by the impulse force hammer test method. Vibration and scattering motions were observed by a high-speed video camera. The result of these measurements indicates that a basic mechanism can be developed that will lead to flow-induced vibration of the roofing tiles. This system is similar to that of fluttering instability, which appears as self-excited oscillation in the structure´s natural mode at a certain critical flow speed. The values of the oscillation frequencies relate to the values of natural frequencies of the vibration.