Application of Iteration Perturbation Method to Coupling Eigenvalue Problems

Abstract

The flow-induced vibrations often cause severe troubles in nuclear reactor components, and hence mechanical engineers must make coupling eigenvalue analyses taking into account some interactions between structures and fluids. In this type of problems, natural frequencies and their associated modes should be calculated with sufficient accuracy, and for such purposes finite element method is usually a convenient tool. However, since conventional methods increase computer costs, more efficient algorithms are necessary for practical design analyses. In this paper we will propose an interation perturbation method to treat such eigenvalue problems. Since proposed method only need eigenpairs for uncoupled problem of structure, necessary ammount of computations reduces, and we can utilize usual finite element solvers installed in many program codes. To see effectiveness of our method in coupling problems, some numerical results are given for free vibrations of a beam submerged in water chamber.