Experimental Study of Fluid Structure Interaction of Carbon Composites under Low Velocity Impact

摘要

The effect of fluid force on the natural frequencies and damping ratios of vibrating structures in contact with fluid is known as the Fluid Structure Interaction (FSI) problem. It can be interpreted as an added mass to the vibrating structure in the analysis of the dynamic response. Because the density of water is much greater than air, the added mass effect becomes even more critical in understanding the dynamic response of composites in water surroundings. In this study, experimental testing was carried out to investigate FSI of composite laminates immersed in fluid and subjected to low- velocity impact. Square composite laminates of carbon fiber weave and vinyl ester resin of size 305 mm and 2.38 mm nominal thickness were subjected to low velocity impact loading, using a specially developed vertical drop-weight testing machine. The composite samples were fitted with gages to provide real- time information on strain levels generated during impact. Impact tests were performed on four side clamped laminates in air-backed, water-backed, and dry surroundings, and at various impact energies for investigation. The findings of this study will provide a better understanding for the use of composite materials in underwater structural applications where impact loading is expected.