Research On Key Problems Of Finite Element Model Updating Of Mill Transmission System

The structure of large mill transmission system is complex,in which there are many uncertain factors.However,in the field of structural dynamic analysis,the finite element simulation technology is mainly carried out in the deterministic framework.Little consideration is given to the influence of uncertain factors in the transmission system on the dynamic characteristics of the transmission system finite element model,which makes the model unable to correctly reflect the dynamic characteristics of the system,so that the simulation results cannot have good industrial applications.Moreover,most of the current model updating methods are based on modal parameters and frequency response functions,while the model updating methods based on time domain response are rare.It is of great significance for the development and application of the finite element method to study and analyze the uncertain factors in the transmission system and to explore the model updating method based on the time domain response.In this paper,the transmission system of a large mill is taken as the research object.The uncertain factors in the transmission system are analyzed and identified by means of combining test and theoretical modeling.Finally,the finite element model which can correctly reflect the displacement response of the transmission system is established.The details are as follows:(1)Based on the similarity theory,a transmission system test-bed suitable for laboratory conditions is designed and built.Taking one gear transmission system of the test bed as the research object,it is divided into different sub-structures based on the idea of layering.The uncertain factors in each sub-structure are analyzed,and the finite element models of each sub-structure considering uncertain factors are established.(2)The modal test is designed and carried out.Based on the modal test data,the design parameters of transmission shaft substructures and bearing substructures are taken as the parameters to be updated,and the finite element model correction technique based on response surface is used to update the finite element models of transmission shaft substructures.(3)The time-varying meshing stiffness of the gear pair is calculated by the Ishikawa algorithm based on theoretical mechanics.The finite element model of the meshing gear tooth substructure is updated by response surface method with the timevarying meshing stiffness as the objective value.(4)The dynamic response test of the transmission system is designed and implemented.Then the finite element model of the supporting pedestal substructure is updated based on the dynamic response test results.Finally,the models of substructures are combined into the overall finite element model of the transmission system,and the simulation results are compared with the experimental results.The analysis results show that the finite element model can accurately reflect the displacement response of the transmission system.