| Bolt connection is a very common connection method in mechanical structure,which is widely used in various mechanical products and plays an irreplaceable role.However,under complex working conditions,bolt connection may loose or even fall off,which may cause serious engineering accidents.Therefore,it is of great scientific significance to study the influencing factors of bolt connection loosening.In this paper,a series of studies have been carried out on the problem of bolt connection loosening from the aspects of realizing parametric modeling of finite element model of bolt and nut,verifying the correctness and accuracy of parametric model and finite element analysis of single bolt and bolt group connection structure loosening.1.Referring to the method of manual modeling of full hexahedral mesh model of bolts and nuts,the parametric generation program of finite element model of bolts and nuts is written in Python language,and the parametric modeling of bolts and nuts is realized.In the modeling process,according to the relationship between the grid nodes and element information of the bolt and nut model during manual modeling,referring to the grid node and element information expression format in the INP file of ABAQUS,the finite element model information of the bolt and nut is output using the written parametric modeling program.2.Based on the generated parametric model,the change of pre-tightening force in the pre-tightening process of bolt connection is analyzed,and the experiment is designed to measure the bolt pre-tightening force in this process.The value of pre-tightening force is calculated by using the theoretical relationship of bolt connection tension and torsion,and compared with the finite element simulation results and experimental values,the correctness and accuracy of the parametric model are verified.3.Based on the finite element simulation method,the influence factors of single bolt connection structure loosening are studied.The influence of different initial preload,load amplitude,friction coefficient and thread fit clearance on bolt connection loosening under axial load and transverse load is analyzed respectively.The bolt connection is easier to loosen under transverse vibration,and the thread fit clearance has little effect on the preload of bolt connection.4.The influence factors of loosening of flange connection bolt group were studied by numerical analysis.The influence of bolt number,bolt arrangement and bolt tightening sequence on bolt loosening in flange connection is studied by simulation analysis.It is found that the arrangement of bolts has a great influence on the pre-tightening force,while the number of bolts and the tightening sequence of bolts have little influence on the pretightening force. |
PDF Full Text Request