Study On The Mechanical Model Of Bolt Connection Under Lateral Load

In petrochemical and other industries,a large number of traditional mechanical structures are often used,and the bolt connection structure is one of the very important ones.In order to ensure the safety,effectiveness,and stable operation of chemical equipments,especially in the nuclear power industry,there are higher requirements for the life of bolts,so a reasonable and meticulous evaluation of the bolt connection structures that are most frequently used must be performed.However,most bolt joints are currently in the empirical design stage,and traditional empirical design calculations are no longer sufficient to meet the requirements of modern engineering structure design.At the same time,bolt joints in the nuclear power industry have been subjected to alternating load impact loads and temperature for a long time,and they often have problems such as loosening,dislocation deformation and even fatigue fracture.Based on this,article studies the bolt joints under side load and proposes a new mechanical model.The main research contents of this article are as follows:?1?The characteristics of the bending deformation of the bolt connection members under the lateral load are transformed into a model of restraining cantilever beams.At the same time,the concept of an equivalent embedding point is proposed,and related theoretical analysis is performed to determine the possible impact.Factor of embedding depth l₁.?2?Using ANSYS software to simulate and analyze the simplified model,and use the control variable method to study the bending deformation characteristics of elastic cantilever beams under different end face diameters,different polished rod lengths,different bending moments,and different polished rod diameters.Analyze the effective length factor.At the same time,the accuracy of the method is verified by comparing the deflection curve with the embedded depth l₁ and the deflection curve calculated from the theoretical formula.?3?A test bed for the bolt connection structure under lateral load using an automatic control loading method was set up to further study the depth of the embedding depth on both sides of the bolt,and the effect of the complexity of the force on the threaded part was considered.In the test,the strain gauge method was used to measure the bending stress of the bolt under lateral load,and the displacement sensor was used to measure the deflection generated when the bolt was bent.The bending deformation of the bolt under different bolt sizes and different pre-tightening forces is considered.?4?The finite element analysis is performed on the bolt connection test model under the lateral load.The relevant contact in the model was established.The virtual thread option was used in the thread part to simulate the effects of different pre-tightening forces and different bolt sizes on the equivalent rod length.Summarize and analyze the data to study the depth of embedding on both sides.Through the simulation and experimental analysis of the bolt connection structure under side load,it is concluded that the simplified constrained cantilever beam model,and because the bolts and couplings are elastomers,the length of the cantilever beam model is due to the length of the bolt rod to both sides Extension.The equivalent rod length L is related to the diameter d₁ of the bolt rod,and has nothing to do with the axial force,the bolt rod length,and the concentrated load.At the same time,the test value is close to the simulation value for the embedding depth l₁ on the side of the bolt head.The simulation average value is 0.305 d₁ and the test average value is 0.338 d₁.For the embedding depth l₂,the simulated average is 0.621 d₁ and the experimental average is0.723 d₁.The dispersion from the model simulation is smaller,the test has errors but the overall is within an acceptable range.The virtual thread definition method for the thread part can be referred to the analysis of the design to the bolt connection structure,and at the same time it is closer to the test value and more accurate.