Eigenproblems from Finite Element Analysis of Fluid-structure Interactions

We present two methods for calculating resonant frequencies and mode shapes for fluid-structure vibration problems. We model the fluid-structure interaction problem using the #-V-P, finite element technique. This eigenproblem is more complicated than for ordinary structural analyses, as the formulation produces a quadratic eigenproblem (similar to those for gyroscopic systems). We derive properties for this quadratic eigenproblem from an equivalent linear problem. From these properties we develop eigenvalue solution techniques based on the determinant search and subspace iteration procedures.