| Many investigations show that randomicity of structures?parameter will bring large value of stochastic dynamic response of structures. Randomicity of structures?mechanics parameter may be dominant factors. Therefore, introduction of randomicity into system model of structure and using random system model are more reasonable than that of determinate system model.The work in this dissertation mainly consists of two parts. In the first part, the dynamic response of nonlinear structures with uncertain physical parameters is studied by means of subsection linearization method and equivalent random systems method, separately. In the second part, a method for analyzing the response of viscoelastic structures with uncertain physical parameters is proposed, with FEM in space domain and discrete method in time domain. The main results of this study are lists as follows:1.The statistical characteristic of frequency response functions of single and two degrees of freedom structures with uncertain physical parameters are obtained by using Monte-Carlo method, and some results are presented. For the single degree of freedom systems, the randomicity of mass and stiffness can considerably weaken the peak value of frequency response functions. While for the two degrees of freedom structures, the randomicity of parameters will increase the peak value of frequency response functions largely. The numerical value simulation of two degrees of freedom structures shows that the small randomicity of mass and stiffness will bring the frequency response functions large perturbation. This fact can not be indicated by the method of sensitivity of the determine model, and must also be considered in measurement.2.Dynamic response of nonlinear structures with uncertain physical parameters is studied by subsection linearization method. The numerical results show that the responses of the proposed approach are much close to the Monte Carlo solutions and that the time of calculation of subsection linearizaton method is much less than that of the Monte Carlo. The results of random structures and determinate structures show that when the ranmomicity of parameters is considered, response of displacement and velocity will occur large changes. In the same condition, there is great difference between response of nonlinear structure and that of linear structure. Thereby, during studying random structures, it is necessary to analyze the nonlinear chrarcteristics.3.It should be pointed out that the subsection linearization method is only suitable for the single degree of freedom system with random mass. When the stiffness and damp are both stochastic, on account of coming down to seek equivalent stiffness, equivalent damp, mean square deviation of equivalent stiffness and mean square deviation of equivalent damp, that method is not applicable. In nature, it is appropriate for the case that the randomicity and nonlinearization of parameters are not coupling. When the randomicity and nonlinearization of parameters are coupled, mass, stiffhess, and damp are stochastic, equivalent random systems method is adopted. In this paper, the formulates are deduced, the arithmetic is presented, and numerical iterative programs of nonlinear structures are compiled. The numerical results show that the responses of the proposed approach are much close to the Monte Carlo solutions and that the time of calculation of equivalent random systems method is much less than that of the Monte Carlo. The equivalent random systems method that is clear in principle, simple in plan, and high in precision of example, will be developed in the2disposal of dynamic response of structures with uncertain physical parameters.4.Developments of study on stochastic finite element method (SFEM) are introduced. For the linear elastic problem, the SEEM is to mature. But the work that analyses viscoelastic random structures is almost not covered heretofore. In this paper, by order expansion stochastic finite element method, a calculation model used in analyzing th...
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