Contact Analysis Of Threaded Connection In Locomotive And Rolling Stock

Threaded connection is an important fastening method widely used in mechanical field.In the design,production and use of non-standard thread,it is very important to analyze the stress of thread structure and check the strength and fatigue.The stability,reliability and safety of thread in work will have an important impact on the use safety and service life of mechanical products.Threaded connection has certain universal law.When bearing the same type of load,no matter whether the length and diameter of the thread are the same or not,it will show the similar stress distribution law.Therefore,through the analysis of a kind of thread structure,the stress results of similar threads can be analogized.The research on high strength non-standard thread products is less than that on common standard thread.So in this paper,the quasi-static elastic contact analysis of the threaded connection is carried out,taking the high-strength bolt of the connecting rod of a diesel engine as an example.Aiming at the phenomenon of high stress concentration in thread,the thread structure is improved and the stress optimization effect of the improved structure is analyzed.The dynamic elastic contact of thread is simulated by loading cyclic load,and the fatigue performance of thread is analyzed.Firstly,using CATIA software to establish the geometric model of the connecting rod bolt thread structure,then build the finite element model of the threaded connection structure by ABAQUS software.According to the boundary conditions and the load conditions,the elastic contact analysis of the thread is conducted by ABAQUS software.Then,according to different preload,different thread number and different center distance of parallel double thread structure,the axial force distribution,contact stress distribution and the influence of various parameters on threaded connection are obtained.Based on the ideal threaded connection model,the thread finite element model with cutting angle and tolerance clearance is established.Then it is imported into ABAQUS software,and the boundary conditions and load conditions are set to be consistent with the ideal model by using the control variable method.The elastic contact finite element analysis of three improved thread models,such as cutting model and clearance tolerance model,is carried out to obtain the influence of different cutting angles and clearance distribution on the stress distribution of the thread.Finally,I compare the ideal thread model with the cutting model.The cyclic load of the model is established in ABAQUS software according to the actual working frequency of the diesel engine.The dynamic stress,velocity,displacement and acceleration of thread structure under cyclic dynamic load are analyzed.And the fatigue performance of the thread is calculated by dynamic stress and stress amplitude.