Gao W., Kessissoglou N.

A new method called the interval factor method for the natural frequency and mode shape analysis of truss structures with bounded uncertain parameters is presented in this paper. By using the interval factor method, the bounded uncertain structural physical parameters and geometric dimensions can be considered as interval variables, and a structural parameter can be expressed as its mean value multiplied by its interval factor. The structural stiffness and mass matrices can then be respectively divided into the product of two parts corresponding to the interval factors and the deterministic matrix. The computational expressions for the lower bound, upper bound, mean value and interval change ratio of the natural frequency and mode shape are derived from Rayleigh quotient by means of the interval operations. The influences of the uncertainties of the structural parameters on the natural frequency and mode shape are demonstrated by using truss structures. The main advantage of interval factor method is the effect of uncertainty of any individual structural parameters on the structural dynamic characteristics can be examined easily.