Research On The Geometrical Parameters Of Bolted Joints Deformation Under Compression

Bolts are one of the most commonly used components in design of construction and mechanical.They are used as connectors to connect industrial structures together.Therefore,in mechanical engineering,the application range of bolts is very wide.The preload required for bolts in service is an important indicator of design and verification of bolts.Therefore,it is of great significance for the accurate calculation of the deformation of the connected parts and programmed calculation of the load introduction factor which are closely related to the required preload of the bolts.In order to ensure the safe use of bolted connections,it is necessary to analyze the interaction between the components and improve the calculation accuracy of the deformation of the connected parts.The dimensional information of the connected parts that do not transmit the load is equivalent,and the calculation process of the load introduction factor is simplified,which is helpful to the proceduralization of bolt verification and is of great significance to the engineering application of bolts.In this thesis,the following researches were carried out on the deformation of the connected parts and the load introduction factor of the bolted connection structure:Firstly,the influence of the size of bolt connection on the initial diameter of the compression deformable body was studied through the comparison between simulation calculation and theoretical calculation.Meanwhile,in order to eliminate the simulation error,the corner method in accordance with the actual pre-tightening process was compared with the pre-tightening element method.The results show that for the M12 bolt connection structure,the guide value of the initial diameter of the compression deformable body is 1.38 times the diameter of the bearing surface.The relative error between theory and simulation does not exceed 3%.The relative error between the simulation results obtained by using the pre-tightening element method and by corner method does not exceed 2%.Then,the bolt connection structure with different sizes of sleeves was established to study the shape of the compression deformable body in the connected parts under the sleeve and the influence of the outer diameter of the sleeve on the compression deformation of the connected parts.The shape of the deformable body that is not symmetrical about the joint surface was corrected.The results show that the compression deformable body under the sleeve continued to spread,and the length of the sleeve is positively correlated with the deformation of the sleeve.The relative error of the formula for calculating the deformation after correcting the shape of the compressed deformable body does not exceed 7%.Finally,in order to calculate the load introduction factor programmatically,the connected parts were equivalently divided into gaskets,sleeves and sliding connected parts.In order to carry out a unified calculation on the sleeve and sliding connected part,the equivalent elastic modulus of the sleeve and sliding connected part was deduced.The dimensional information of the sleeve that does not transmit the load was equivalent.And the calculation formula for the deformation of the sliding connected part that only needs the length of the sleeve and sliding connected part was deduced.The relative error between theory and simulation does not exceed 2%.In this thesis,the study of the deformation of the compression deformable body in the bolted connection is used to promote the calculation accuracy of the required preload of the bolt.The dimensional information of the sleeve that does not transmit the load was equivalent to provide a reference for the programmed value of the load introduction factor,which has certain engineering application significance.