A NEW METHOD FOR COMPUTING THE UPPER AND LOWER BOUNDS ON FREQUENCIES OF STRUCTURES WITH INTERVAL PARAMETERS

In this paper, we will investigate the method for computing the upper and lower bounds on frequencies of structures with bounded uncertain ( or interval) parameters. The stiffness matrix and the mass matrix of s tructures, whose elements have the initial errors, are unknown except for the fact that they belong to given bounded matrix sets. The set of possible matrices can be described by the interval matrix. By means o f the stationary condition of Rayleigh Qutient and the minimax theorem of eigenvalues, the generalized eigenvalue problem of structures with bounded uncertain parameters can be transformed into two different ge neralized eigenvalue problems. The numerical results indicate that the proposed method is effective.