Research On The Influence Of Tower Crane On Bolt Connection Looseness Factor

The tower crane is widely used in the construction project because of its obvious advantages in the working range,lifting height,efficiency etc.Threaded connection is widely used in the production of mechanical industry,which can be used as a removable fixed connection,one of the main connection methods of tower crane standard section is screw connection.There are many factors that affect the stability of screw connection in practical engineering,such as the choice of the thread,the selection of the pitch,the direction of the load,the magnitude of the load,etc.The main failure form of bolt connection is the self-loosening,which results in the decrease of the stress of the threaded part,the phenomenon of relative slip is found to reduce the stiffness of tower crane,affect the safety of tower crane in the use of the process,the serious will cause the tower crane standard section of broken,leading to major accidents.This paper uses QTZ5510 of tower crane standard section bolt connection as the research object,the finite element contact model is used to simulate the process of bolt connection looseness under transverse load and axial load,to understand the influence of different factors on the loosening of bolt connection.1)The Yamamoto analysis method and Junker relaxation model for the distribution of the bearing capacity of bolt connection pairs are studied,this paper analyzes the force of the thread and compares it with the loose model,and uses the analytic method to obtain the analytical solution of the distribution of the bearing capacity of the bolt.2)The 3D finite element contact model of bolt connection is established by means of Pro\E,Hypermesh and Abaqus three software.A three-dimensional finite element model of bolt connection with spiral angle was established in Pro\E,then the Hypermesh is used to perform the meshing of the hexahedron mesh and the setting of the pretreatment.Finally,the boundary conditions are set in the Abaqus,the load step is set and the preload is applied.The static analysis is carried out,and the simulation results of the distribution of the bearing capacity of the screw pair are obtained by applying the method of pre tightening force directly.By comparing the analytical method and simulation method of the bearing capacity of the distribution curve,verify the method of applying preload is effective and finite element model.3)The dynamic finite element analysis of the model under lateral dynamic load,the vibration frequency and amplitude of the tower crane are selected,the influence of the vibration frequency,the amplitude of the transverse displacement,the friction coefficient of the friction coefficient,the friction coefficient of the bearing surface and the different pitch on the bolt looseness are studied.4)Dynamic finite element analysis under axial dynamic load,the vibration frequency and amplitude are consistent with the lateral dynamic load,the influence of the vibration frequency,the amplitude of the transverse displacement,the friction coefficient of the thread,the friction coefficient of the bearing surface and the different pitch on the bolt connection stability are studied once again.The research of this paper is to find out which factors have great influence,the utility model is favorable for avoiding the influence of the unfavorable factors,and is convenient for selecting the suitable bolt connecting pieces to improve the safety of the tower crane when used,and can effectively prevent the self loosening of the bolt connection of the tower standard section.It has important application value and practical significance to ensure the safety of tower crane,avoid the occurrence of major accidents and reduce the risk of accidents...