Frequency modification using Newton's method and inverse iteration eigenvector updating

An iterative procedure is proposed for determining structural changes necessary for modifying natural frequencies of a structure in a prescribed manner. The procedure uses a Newton's method approach to determine a structural change that satisfies the equation of motion of the modified structure. The Newton equation is the same as that derived from sensitivity analysis and from linear perturbation methods. Iterative application of this equation can be used to predict accurately the structural change for either large or small frequency modifications. Inverse iteration is used to update the structural eigenvector between Newton iterations. The application of this procedure to a finite element analysis is described. Natural frequency modification of a finite element structural model is shown to converge rapidly to accurate results. (Author)