Fluid Structure Interaction Effects on Composites Under Low Velocity Impact.

摘要

In this study composite materials were tested in different fluid environments to determine the role of Fluid Structure Interaction with these composites under a lower velocity impact. The purpose of this research is to develop a better understanding of possible marine applications of composite materials. This was done using a low velocity impact machine and two composite types. The first composite is made from a multi-ply symmetrical plain weave 6 oz. E-glass skin. The test area of the composites is 12 in by 12 in (30.5 cm by 30.5 cm) with clamped boundary conditions. The testing was done using a drop weight system to impact the center of the test area. A Plexiglas box in conjunction with the impact machine was used to keep the top of the composite sample dry while it was submerged in approximately 15 inches (38.10 cm) of water. The second composite type was constructed using the same methods, but was made from a Carbon Fiber Reinforced Polymer (CFRP) instead of the E-glass skin. These samples were pre-cracked and tested using the same impact machine in 15 inches (38.10 cm) of water. The overall size of these samples was 42 cm long and 3 cm wide forming a long thin rectangular shape. The test area of these samples was a 20 cm long section of the sample with the outsides being clamped to achieve the desired boundary conditions. Two variations of these samples were tested. The first was reinforced with Multi-Walled Carbon Nanotubes (MWCNTs) and the second had no reinforcements at the interface layer in front of the pre-cracks. Output from both tests was recorded using strain gauges and a force impact sensor. The results show that an added mass from the water plays a large role in the Fluid Structure Interaction with composites due to the similar densities of water and the composites.