Analysis of the coupling mechanism between gear-rack meshing and wheel-rail rolling contact of rack railway

Subjects: Traffic and Transportation Engineering >> Railway Transportation submitted time 2024-02-07 Cooperative journals: 《应用力学学报》

WANG Zhenhuan

Abstract：
A three-dimensional transient contact finite element model based on explicit time integration is developed for the rack railway suitable for mountain rail transit.The medium and high frequency coupling dynamic interaction between gear-rack meshing and wheel-rail rolling contact can be analyzed in time domain.Factors such as the true geometry of the wheelset and track,the ‘wheel paradox’ caused by the diameter difference between the gear and the wheel,and structural vibration are taken into account.The gear and rack meshing and wheel-rail contact are both solved by a surface-to-surface contact algorithm with the Coulomb friction integrated.Considering the zero and non-zero wheel-rail friction coefficients,the influence of the ‘wheel paradox’ on the gear-rack meshing and wheel-rail rolling contact can be deconstructed.Taking the Strub rack railway as an example,the dynamic contact phenomena under a running speed of 10 km/h and slopes of 0‰,240‰ and 480‰ are investigated.The results show that the contact forces of gear-rack and wheel-rail show periodic fluctuations due to gear meshing,but the vertical total force and total traction torque fluctuate near gravity load and traction torque,respectively.The wheel paradox makes the vertical contact force and normal stress of the rack decrease,while the vertical contact force and normal stress of the wheel-rail increase.In terms of the tangential contact solution,the tangential contact stress of the tooth surface and the slip area in the contact spot increase.Under the condition of slope 240‰,the wheel-rail friction coefficient increases from 0 to 0.2,the maximum normal contact stress of rack and wheel-rail increases from 248.69 and 752.66 MPa to 195.17 and 757.44 MPa,and the maximum tangential contact stress changes from 24.48 and 152.84 MPa to 21.31 and 2.14 MPa.The wheel-rail contact presents full sliding contact due to significant creep.Under the same speed and friction conditions,the increase of slope makes the vertical force and traction force of rack increase,the vertical force and traction force of wheel and rail decrease,and the contact stress has the same change.

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