Research On Assembly Stress Of Aluminum Alloy Crossbeam Of EMU

With the rapid development of EMU technology,more and more attention has been paid to the safety of EMUs.The aluminum alloy crossbeam of the underbody of the car body is the key structure connecting the equipment under the EMU and the car body,which is crucial to the safety of the vehicle.It is one of the common ways for rail vehicles to hang the under-vehicle equipment on the beam through bolts.This article takes the connection structure of a certain type of EMU beam and converter as the research object,mainly studies the assembly stress of the beam and its connection structure,and explore The effect of bolt preload and horizontal clearance between each lifting point of the beam on its assembly stress.Firstly,a method for calculating the eccentric load distribution is obtained through theoretical calculation,and it is applied to the model where the beam hangs the converter through four hanging points.The load values at the four hanging points are obtained.Referring to the theoretical calculation results,the simulation conditions of the single-lifting point hoisting structure were established,the finite element model of the single-lifting point hoisting structure was established,and the stress distribution at different points under different loads was studied.The results show that under different loading conditions,the stress distribution of the beam is basically the same,the maximum stress occurs at the place where it contacts the bolt head,and the stress at the corner of the T-slot of the beam is also larger compared to other areas.In order to study the influence of assembly factors such as bolt preload on the assembly stress of the beam,the assembly stress test of the beam through the four-hanging point suspension structure was carried out.The test results show that with the increase of the preload of the bolt at a certain suspension point,the assembly stress at the suspension point of the beam will decrease accordingly,so in the actual assembly process,the preload of the bolt at the suspension point with a larger stress value can be appropriately increased.Since the test can only measure the preload force outside the T-slot of the beam,a finite element model of the four-hanging point hanging structure was established,and the contact pairs were used to more realistically simulate the beam,rectangular bolt and converter hanger.The assembly stress is compared with the test results,and the results are basically consistent.When studying the hanging structure of the fourteen suspension points of the beam,the calculation of the bolt solid modeling is large,and the stress at the suspension point of the beam is more concerned.Therefore,a more simplified modeling method was used to establish the finite element model of the connection structure,the stress distribution of each hanging point is analyzed,and its static strength meets the static strength standard EN 12663 standard.The influence of the horizontal clearance between the lifting points on the assembly stress of the beam is analyzed through experiments.The test results show that the existence of the clearance will make the stress level of the beam hanging points increase significantly,and the more the number of hanging points at the same height,the more the beam The greater the stress level,in actual engineering,the height of each hanging point of the beam should be adjusted as much as possible.