Identification Of Structural Distributed Dynamic Load Based On Strain Modal Method

Identification of dynamic load applied on mechanical structures has been a valuable problem in the field of scientific research and engineering application.After years of in-depth study,the identification of the concentrated load has been well solved,while the identification of distributed dynamic load with more engineering application vaule is still a problem to be solved.The introduction of orthogonal polynomial theory provides a reliable theoretical basis for the identification of distributed load.In this method,the continuous distributed load is represented by polynomial interpolation,which transforms the identification of distributed load into the problem of the identification of the basis function coefficients.At the same time,the development of strain mode theory established the relationship between structural strain response and input load.Combining the strain modal theory and the identification of complex distributed load based on generalized orthogonal polynomial theory,this paper proposed the techology of identification of structural distributed dynamic load based on strain modal method.This method established the model of distributed load identification by using the structural strain response and the strain transfer function as the known parameters.Using this method,we only need to obtain the strain response of the finite measuring points on the structure,so that we can calculate the interpolation function coefficient according to the the strain frequency response function of structure and orthogonal polynomial theory,and then get the function expression of distributed load with the form of basis function superposition.In this paper,the displacement modal method and the strain modal method are both used to analyze the load distribution.Through numerical simulation,this paper verifies the distributed load identification method of simple suportted beam model,rigid beam model as well as simply supported rectangular plate model,and then analyzes the numerical stability and error introduction problem of load identification.The simulation examples show that the techology of identification of structural distributed dynamic load based on strain modal method proposed by this paper has high identification accuracy,and has obvious advantages in numerical stability and error control aspects than the traditional displacement load identification method.