Bounds of complex eigenvalues of structures with interval parameters

Based on the interval finite element method, a new method is presented in this paper to determine the bounds of complex eigenvalues for damping structures with interval parameters. The calculations are done on an element basis, hence, the calculations are greatly simplified. As an application of the method, a numerical example of a spring–mass system with damping is given. In order to illustrate the accuracy of the present method, the results obtained are compared with those obtained by Ref. [14] (Qiu ZP. Interval analysis for static response and eigenvalue problem structures with uncertain parameters. PhD thesis, Jilin University of Technology, 1994. p. 91–100 [in Chinese]). The calculated results show that the proposed method in this paper is effective in evaluating bounds of complex eigenvalues for damping systems with interval parameters.