Finite Element Model Updating Of Structures Based On Time Domain Data

Finite element model updating is one of important research content in structure health monitoring system, the accurate finite element models for the prediction of structural dynamic characteristics and design of structures show significant meaning. Due to the complexity of structures and indefinite factors in the process of analysis such as the simplification of models,the error of material parameters, boundary conditions and so on, which all can cause errors between dynamic characteristics of finite element models(FEM) and dynamic characteristics of practical structures, and the calculated results are not very close to the experiment measured date. It leads to more difficult if we apply finite element calculated results to assess structure condition and predict the residual life of structure. In this paper, the method of structural FEM updating based on time domain responses is proposed. The functional relationship between residual errors and structural parameters and the response surface models of time domain are achieved by comparing the time domain responses of experiment and FEM. Based on response surface models, the parameters of structural FEM are updated by optimal calculation. The detail research contents of paper are as follows:(1)The principle of FEM updating based on structural time domain responses, the research status and basis steps are introduced. Regarding a simple supported beam(SSB) as case, the damage of a SSB on basis of the elastic modulus variation is identified, and the model is updated using the method based on time domain. The time domain responses of updated FEM are closely consistent with the time domain responses of factual model. The effectiveness is validated.(2)The FEM of SSB based on the test data by hammering test of a SSB is updated. The acceleration responses of updated FEM are closely consistent with measured acceleration responses. Results reveal that the FEM by updating can as benchmark model analyze the mechanical characteristics of practical structure accurately.(3) The FEM of a five-story frame structure was updated in adding white noise in the test model analysis data and without noise of two different working-modes. Results show that the FEM after updated of two different working-modes can calculate the time domain responses of experimental model, the optimization results which without white noise join in the test model analysis data are better than white noise add in the test model analysis data optimization results. The method of FEM updating based on time domain responses can use to update the FEM of practical structures with high update accuracy.The results show that the method of FEM updating based on structural time domain responses can reduce the iterative times and improve model optimal efficiency. The updated FEM can precisely reflect the mechanical performance of practical structures, and which can regard as the benchmark model for following structural performance evaluation.