Parameter Identification Based On Experimental Modal Analysis For Uncertain Structures

In the identification of modal parameters of engineering structures,there are various uncertain factors in the attribute data,dimension measurement,boundary conditions and cognitive judgment of structural materials,which lead to a large deviation between the actual dynamic characteristics of structures and the nominal design values and seriously affect the accuracy of the identification of modal parameters.Most researchers at present focus on the theoretical and experimental methods of modal parameter identification of deterministic structures,but the identification of model parameters in an uncertain environment is still in its infancy.This paper presents a method for identifying structural physical parameters in an uncertain environment.This method is based on the modal data identified by experimental modal parameters.Uncertainties in the structure which reflect the dispersion of material properties used and the aging process of existing structural materials are described using interval parameters.Taking Taylor expansion of the eigenvalue function at the nominal point of the material property,we can obtain interval algebraic equations for structural modal parameters and material attribute parameters.Inversion of material properties parameters can be obtained based on linear programming theory.The derivative of the used eigenvalue function is obtained using the difference method.Numerical examples show the structural parameters can be effectively inverted based on the modal parameter data when the nominal value of the material is known and have enough accuracy within a certain material dispersion range.