Finite Element Model Updating Based On Sensitivity And Response Surface And Software Development

The structural error and parameter error of the finite element model lead to the inaccuracy of the model.It is necessary to improve the accuracy of the finite element model through the model updating technology,so that the modified finite element model can provide reliable basis for dynamic modification,response prediction and so on.At present,the model updating technology based on sensitivity method and response surface method are comparatively ripe.In this paper,the software implementation of the finite element model correction technology is the starting point,and the two modified methods were studied.The specific research contents are as follows:First,the theory and the realization steps of the finite element model correction method based on sensitivity were introduced.In the mode matching of correlation analysis,the mode shape of finite element model were reduced based on the position coordinates of the test point and the model shape of the test.In view of the limitation of the finite element software on the solution of sensitivity,the difference sensitivity was selected and its feasibility was determined by comparison with the analytical sensitivity.According to the finite element method and the analytical method of sensitivity analysis,the analytical method of sensitivity analysis based on the characteristics of the element was derived.The effect of insensitive variables on the correction effect was studied by the perturbation method.It was found that it has little influence on the convergence of the modified target.Then,the correction process and the basic theory of the model correction method based on the response surface are studied.The accuracy of the response surface model was verified by the experimental sample points and the random points data.Two methods were used to correct the bolt plate model.Two methods were used to correct the bolt plate model.Compared with the correction effect,it was found that the correction method based on response surface can reduce the call to the finite element software in the correction process,and the correction speed is faster.However,the response surface model also produces some errors,and the precision of correction result is slightly lower than the sensitivity method.The model updating software was developed based on ANSYS and MATLAB with two updating methods.According to the modal analysis ability of ANSYS,the powerful data analysis and computing power of MATLAB,developed the interface of ANSYS input data files(CDB),output data files(RST)and test data files(UFF),and the software of model updating technology was realized.Finally,the torsional vibration analysis was carried out on the centralized mass system model of a type of six column reciprocating compressor.It was found that the first order natural frequency of the shafting was close to the speed of five times,and there is a danger of torsional resonance that may cause the failure of the shaft system.The flywheel was modified by the model correction method based on sensitivity,which avoided the torsional resonance and optimizeed the performance of the shafting.