Research On Interval Method And Its Application On Analysis Of Antenna Structure

A large number of errors and uncertainties exist in the actual structures. In the process of structural analysis and design for engineering, uncertainties can not be ignored simply. At present, there are three main methods for uncertain modeling, such as probability method, fuzzy method and interval method. With acquiring the upper and lower limit of structural parameter, interval method can be used, which is an effective method which probability density and membership function is not obtained. Static response analysis and the dynamic characteristic analysis of complex structure are made by using of interval method. The main research works can be described as follows:Interval factor method is applied to analyze antenna structure. Uncertainties of the interval variables are represented by interval factors and interval variables are described as mean values multiplied by interval factors. The finite element analysis of the 8m-diameter antenna structure with interval parameters under different interval load is studied. According to the structural interval displacement and stress response, the structural displacement and the element stress were obtained under different load. The effects of any one of uncertain structural parameters or load on the displacement and stress are examined by some interval models.Interval factor method is applied to analyze dynamic characteristics of antenna structure. Under the condition that the structural parameters are interval variables simultaneously, the structural stiffness matrix and mass matrix are constructed by using interval factor method. From the Rayleigh expression of structural vibration, the computation expressions of interval variables of structural eigen values are obtained on the basis of principle of interval arithmetic. The method presented in this paper is verified. By the method, the effect of uncertainty of any individual antenna structural parameters on the structural dynamic characteristics can be reflected.Structural analysis of random and interval hybrid model is made by using of interval factor method and random factor method. Random quantities and interval quantities in the model are described by interval factors and random factors multiplied their mean values. Calculation of interval and random parts is carried on respectively: According to the structural interval displacement and stress response, the structural displacement and the element stress were obtained under the load; According to the random factor method, the computational expressions of the mean value and mean variance of the structural displacement response and stress response are deduced by algebra method. The mean value and mean variance of the structural displacement response and stress response with the interval character are obtained by the hybrid calculation of interval and random parts. The effects of interval or random parameters on the displacement and stress can be examined.