用鲍维尔法估计物理参数

THE ESTIMATION OF PHYSICIAL PARAMETER BY POWELL METHOD

本文介绍一个用鲍维尔方法对目标函数进行优化,得到线性结构的质量、刚度和阻尼矩阵元素的物理参数估计方法,给出了一个仿真实验的实例,并考虑了测量误差对估计参数的影响。

The estimation of physical parameter means that the elements of structural mass,damping and stiffness matrix can be obtained from the input and output data,The Mathematical model which is used to compute structural response may be modified by usnig estimated physical paramaters.The output error method is used to get objective function in this paper,the structural response can be calculated by Newmark or Wilson method for a given set of parameter and mesured input excitation. The Powell approach is adapted for optimization.The global minimun value may be found by random search method. An example of a two DOF system subjected to a EL-Centro earthquake is shown in this paper.The results show that the objective function has savaral local minimun values.some sets of physical parameters correspond to a set of nearly same modal parameters.The damping factor coverage quickly.The phy- sical parameters of linear structures can be satisfactorily given by this method. The effect of noise on estimated parameters is also cosidered in this paper.