LDV-based vibration measurement of a stiffened plate covered by a rubber coating with multi-layered periodic porous in air

To control underwater acoustic radiation of ships and protect against detection, coatings are attached to the vibrating wet surface of the hulls. Coatings with different pores or scatterers enclosed will attenuate vibration and suppress sound radiation with different mechanisms. However, there are very few experimental studies concerning vibration measurement of a coated structure in water, mainly due to the water environment. A compromised way to reveal the attenuation mechanism is to measure the vibration in an anechoic chamber. A stiffened plate covered by a rubber coating with multi-layered periodic porous is measured by a LDV scanning system in this study, which is aimed to minimize added mass effect of contact measurement. Comparative measurements on bare stiffened plate and stiffened plate covered with solid rubber are also carried out. Vibration transmission from the stiffened plate to the coatings as well as vibration modes on the radiating surface for the three tested objects is obtained. The vibration and sound attenuation mechanism of the proposed rubber coating is unveiled.