Numerical modal analysis of composite structures coupled with water

Dynamic characteristics of polymer composite beam and plate structures were studied when the structures were coupled with water. The effect of Fluid–Structure Interaction (FSI) on natural frequencies, mode shapes, and dynamic responses was examined for polymer composite structures using multiphysics-based computational techniques. Composite structures were modeled using the Finite Element Method. The fluid was modeled as an acoustic medium using the Cellular Automata and finite element techniques. Those techniques were coupled so that both fluid and structure could interact bi-directionally. In order to make the coupling easier, the beam and plate finite elements have only displacement degrees of freedom but no rotational degrees of freedom. Then, the numerical modal analysis technique was applied to the composite structures with and without FSI, respectively, so that the effect of FSI can be examined by comparing the two results. The study showed that the effect of FSI is significant on dynamic properties of polymer composite structures. Some previous experimental observations were confirmed using the numerical modal analysis.