| The wheel-rail system in a large radio antenna is the foundation of the antenna’s azimuth rotation and supporting,which realizes by the rolling contact between wheel and rail.The wheel-rail combination is the important part of the large radio antenna wheel-rail system,and its contact rolling working well or not will directly affects the operation of the antenna.Therefore,based on the national observatory 50 m radio antenna wheel-rail combination,the wheel-rail rolling contact problem is researched.First,based on the rigid-flexible coupling dynamics theory,the methods to establish and solve the dynamics equations of large radio antenna wheel-rail contact rigid-flexible coupling multi-body system are discussed.And the method to model the wheel-rail rigid-flexible coupling contact dynamics model is discussed,which provide a theoretical basis to the next simulation.Next,by using the MSC.Patran/Nastran and RecurDyn and analyzing the rolling contact parameters between wheel and rail and its boundary conditions,the wheel-rail contact rigid-flexible coupling dynamics simulation model is established.According to three different conditions(startup,smooth operation and fast braking),the model of smooth rails analyzed.Findings are as below: in the startup and fast braking,the stress and deformation of rail are twice bigger than in the smooth operation.The max stress and deformation in the rail happens in the instantaneous start,the max stress is 559.64 Mpa and the max deformation is 0.153 mm.On the analysis of the dynamic relationship between points’ stress and deformation and the distance from the wheel to the point,a nonlinear inverse relationship is found.Then,in order to research the relationship between mechanical properties of rail joint and the different wheel impact speed,the wheel-rail model is analyzed at rail joint under the different impact speed.The stress and deformation of rail joint is found bigger under low speed(0.6rad/s)impact rather than the high speed(3rad/s),the max stress is 666.32 Mpa and the max deformation is 0.13 mm.Therefore,in the premise of ensuring the accuracy of the antenna operation can be appropriate to improve the antenna azimuth rotation speed.The study of the mechanical properties of rail with different rail joint angle(30°,45°,60°,75°)is compared,finding the best joint angle is 45°.Finally,we takefield experiment to the 50 m antenna wheel-rail contact system: 1)Measuring the full rail levelness,finding the overall levelness of rail is asymmetrical.And two rail joints have big levelness deviation.The reason is that the fixed bolt at the rail joint is loose.2)Measuring the deformation of rail at different distance from the point of the rail and comparing to the simulation result.We find the measured deformation has not reached the max when the action point of the wheel reaches the preset point.The main reason is the rail joint.3)Measuring the deformation of rail in different locations after the rail loading and comparing the measured data with the simulation result,in the smooth rail,the comparison result is consistent,but at the rail joint the error is big,which shows the rigid-flexible coupling model of joints still has large deviation and the dynamic model parameters need to be revised.The research of this thesis can provide technical guidance to the parameter identification and model modification of wheel-rail rigid-flexible coupling contact,and can also provide a reference to the wheel-rail wear and the rail joint impact deformation. |
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