Model Updating Of The Single Beam Crane Based On Operational Modal Analysis

With the development of industry,beam crane has become irreplaceable equipment in modern production.It plays an important role in all fields of economic construction.However,the active beam cranes are mostly produced in 80 s and 90 s of the last century.Under dynamic load such as cyclic loading and forced vibration,fatigue damage and joint loosening will take place,the failure due to long-term structural damage accumulation will lead to disastrous consequences and great loss of property.In order to design the structure accurately and improve the performance and stability of the crane,it is necessary to study the dynamic characteristics of the crane.The operational mode is the dynamic characteristic after the structure bears the working load,which is closely related to the damage of the structure.In this paper,a single beam crane is taken as the research object.Based on the operational modal analysis,the modal parameters are obtained to complete the model updating.The main research work of this paper is as follows:(1)The model updating theory,the finite element modeling method and the computational modal extraction method are studied.The half power spectrum theory and Poly-reference Least Square Complex Frequency domain method(pLSCF)in modal analysis are studied,and a simulation example is compared with other identification methods,which proves that it has good recognition effect.(2)The structural components of the single beam crane in the laboratory are simplified,using the thin layer element insteads the bolt connection and the geometric model is established.The calculated modal analysis is carried out and the first twelve order natural frequencies and modes are obtained.Then the optimal layout of the sensor is explored to determine the number of sensors and the location of the sensor in the operational test.Finally,based on the mode analysis,the excitation position is selected on the main beam of the single beam crane,and the feasibility of the selected excitation position is proved by the harmonic response analysis.(3)The dynamic characteristic test and operation modal analysis of the single beam crane are carried out.The way of excitation and the supporting way of crane are analyzed.The sensor is selected and arranged,and then the data acquisition of single beam crane under the running state is carried out.Then MATLAB is used to establish a measurement model of the crane,preprocess imported test data and check the signal,establish the association of the measurement model and experimental data.Using the pLSCF algorithm based on half power spectrum to identify mode and obtain the steady state diagram,then list its natural frequency and vibration mode.(4)Based on the acquired natural frequency and vibration mode,the model of single beam crane is updated.Through the correlation analysis of the vibration mode,the results of the test and the finite element calculation are corresponded.Secondly,the final updating parameters are determined by the sensitivity analysis,and the experimental design is completed by the central composite test design method.Then the response surface between the input and output is established by using the quadratic polynomial functions,and the fitting precision and prediction ability of the response surface are evaluated.Then multiobjective genetic algorithm is used to determine the updating results of the modified parameters.Finally,test points are selected on a single beam crane,and the frequency response curve is obtained by hammering method.At the same time,the updated model is used to simulate,and the accuracy of the updated model is verified by analyzing the error of the frequency corresponding to the peak frequency of the frequency response curve.