A generalized eigenvalue problem with an elliptic fourth-order operator in a domain with a piecewise-smooth boundary is approximated by a finite element scheme. An efficient iterative method is suggested for evaluating the smallest eigenvalues of the constructed generalized algebraic eigenvalue problem, and an estimate is found for the complexity of the iterative method. The results are illustrated by using as examples three main types of problems arising in the theory of elastic plates. This paper is connected with the author's previous publications [6][7][8][9][10][11][12][13][14] and is devoted to effective numerical procedures of finding the smallest eigenvalue λ ί of eigenvalue problems with linear elliptic fourth-order operators in a bounded domain Ω on the plane with a piecewise-smooth boundary Γ. Such problems can be written in the operator form Lw = AMw, 0<λ ί <λ 2 <·-(0.1) with bounded symmetric linear operators L and M in Hubert space H, where L and M are self-adjoint and positive definite; L~1M is a compact operator. The Hubert space//can be of the form//! χ H 2 χ ··· χ // p ,where// r isasubspaceof the Sobolev space W\(£l) if 1 < r ^ k^ ^ p, and a subspace of W\(ty ifk 1 k( see [3,4,24]). The elements of H are denoted by w = {w { ,..., w p }. Let the eigenspace corresponding to λ ί consist of functions w such that Wr eW m(r) + y (Q), y>0 , l^r^p (0.2) where w r is the rth component of any eigenfunction w corresponding to m(r) = 2 if I k 1 . The main result of the paper is the construction, under proper conditions on the types of the boundary value problems, of some variants of the finite element method (FEM) and iterative methods (IM) for finding the smallest eigenvalues of the arising algebraic problems such that an approximation of λ± with 0(e 2 )-accuracy may be obtained at the computational cost of W(s) arithmetic operations, where W(s) = 0(s-2/ ?\lns\ l \ 1=12. (0.3)A generalization is possible if the condition Μ > 0 is not satisfied and λ 1 is either the smallest positive or the largest negative eigenvalue. For such problems, the estimates (0.3) are still valid. The admissible boundary conditions can be of a rather general nature. If, for example, either the equation Δ 2 νν> = λ\ν or Δ 2 νν = -ΑΔνν is considered, then the boundary conditions can be any of three main types known in the theory of elastic plates that correspond to the cases of clamped, simply supported, and free plates. Brought to you by | University of Arizona Authenticated Download Date | 7/5/15 3:09 PM Brought to you by | University of Arizona Authenticated Download Date | 7/5/15 3:09 PM