Strength And Modal Analysis Of The Straddle Monorail Train Gearbox

As the power component of a straddle monorail,the stability and reliability of the gearbox is directly related to the safety of the train.With the increase of the application range of the inter-seat monorail,the speed of the train is also increased,which makes the requirements for the light weight and stability of the train set become more demanding,requiring the gearbox to reduce its weight and at the same time must have sufficient strength to meet the requirements of the safe operation of the train.In the process of train operation,the gearbox is not only subjected to the excitation load from the motor,but also to the impact load from the wheels and rails.In order to ensure the safe and reliable operation of the gearbox at the initial stage of design,it is often necessary to perform strength checks and modal analysis on the gearbox.Based on the above requirements,this paper performs strength calculations and modal analysis of the gearbox under extraordinary conditions as well as common conditions in the operating condition of the train,performs harmonic response analysis of the box,and calculates the fatigue life value of the box under standard load as well as vibration load of the wheel and rail.The main work is as follows.(1)The bearing loads under each operating condition were obtained by accurate modeling with RMAX software,the model of the gearbox was simplified using Solid Works,the finite element model of the gearbox was established using Hypermesh software and the motor load,vibration load and gravity load were applied,calculated by MSC Nastran software,and post-processed by Hyperview to obtain The stress values and stress cloud diagrams of the gearbox under the extraordinary and common operating conditions are obtained through Hyperview post-processing,and the results show that the gearbox design meets the requirements of the operating conditions.(2)On the basis of the above finite element model,the computational modal analysis of the box body and the constrained modal analysis of the gearbox as a whole are carried out to obtain the modal parameters of the box body and the gearbox as a whole in the first six orders.The results show that the vibration amplitude of the outer side of the gearbox is larger,and the ribbed plate structure can be added to the outer side of the gearbox if the stiffness of the gearbox is to be improved.(3)Based on the modal analysis,the harmonic response analysis of the external excitation of the wheel track on the box was completed,and the "frequency-stress" curves of the box in X,Y and Z directions were obtained,which showed that the maximum stress of the box in the Z direction was 3.87 MPa,which was much smaller than the yield strength of the box material,and the box would not be damaged under the external excitation.The box will not be damaged under the external excitation.Based on the previously calculated stress response values of the box under standard load and the results of harmonic response analysis of wheel-rail to gearbox,the fatigue life values of gearboxes with different casting grades under standard load or wheel-rail impact load were calculated using BS＿EN-1999-1-3 "Fatigue Design of Aluminum Structural Parts" standard,and the results showed that the increase of casting grade can improve the fatigue life of the box.