| The linear induction motor(LIM)metro system is a new type of urban rail transit,of which the type of driven is different from rotary motor(RM)metro vehicle.Based on vehicle/track coupling dynamics theory,the RM metro vehicle/track coupling dynamic model and the LIM metro vehicle/slab track coupling dynamic model are developed.In these models,the vehicle is simplified as a multi-rigid-body system,in which the structures are connected by the spring-dampers,the RM metro vehicle system and the LIM metro vehicle system have 42 DOFs and 44 DOFs,respectively.The track model is composed of the rails,the fastenings,the slabs and the ballast,A Timoshenko beam is used to model the rails which are discretely supported,and the vertical,lateral and torsional vibration is considered.Aimed at DTVI2 fastening and vanguard fastening,the fastening system dynamic models are developed,respectively.The slab is simplified as the three-dimension solid FE(finite element)model.In the LIM metro vehicle/slab track coupling dynamic model,the LIM is modeled by the Euler beam,the vertical and lateral vibration is considered,the longitudinal motion is consider as rigid motion.The RP is also modeled by the Euler beam.In the wheel/rail coupling model,the normal forces of the wheel/rail are calculated by using Hertzian contact theory,the creep forces are determined with the nonlinear creep theory by Shen et al.A "Moving Track" model is used to simulate the train/track excitation caused by the periodical discrete sleepers.A T-type equivalent circuit model is established,and the vertical and lateral electromagnetic force between the LIM and RP is fitted as a non-linear function of air gap.The main research works are as follows:(1)The effects of the measurement of wheel/rail irregularities at field on the dynamic response of the wheel-rail are analyzed.The deterministic irregularities were as the input of the excitation of wheel-rail interface,and the effects of the irregularities characteristic parameters are are analyzed systematic.Based on these,the allowable irregularities amplitude of the LIM metro line determined,which can be the maintenance management of wheel/rail irregularities on LIM metro line.(2)The wheel/rail dynamic response and the interaction characteristics of the two types of metro vehicle under traction force are compared,and the effects of the traction force and the curve radius on the the interaction characteristics of the two types of metro vehicle at curve negotiation are analyzed theoretically.(3)The effects of the wheel/rail short wave irregularities,the stiffness of the LIM suspension,and the form of the track fastening on the vibration of LIM and the air gap are investigated preliminary.The research results show that:(1)The wheel/rail short wave irregularity causes severe wheel/rail dynamic interaction,the irregularities characteristic parameters and vehicle velocity has significant effects on the system dynamic response.(2)Under driving conditions,the traditional RM metro vehicle relies on the wheel/rail adhesive,however,the wheel/rail creep and dynamic interaction characteristic of LIM vehicle is hardly affected by traction force,and its wheel/rail creep force is not limited to the wheel/rail creep saturation,which is different from RM metro vehicle.LIM metro vehicles are better than traditional RM metro vehicles in terms of the guidance capability of guide wheelset at curve negotiation.When passing through a curved track,with the increase of driving coefficient,the difference of the inside and outside wheel/rail longitudinal creep force of traditional RM metro vehicle is reduced,and the guide moment is reduced contemporary,resulting in the reduction of the guidance capability of guide wheelset.However,the wheel/rail creep characteristic and the dynamic response of LIM metro vehicle is hardly affected by traction load.(3)Compared with long wave irregularity,the wheel polygon wear,the rail corrugations and the welding irregularity have less influence on the air gap,however,their effects on the vibration of LIM are significant.The effects of the stiffness of the LIM suspension on the vibration of LIM and the air gap aresignificant,the scratches phenomenon between LIM and RP will happen when the stiffness is small.The type of the track fastening have a significant effect on the vibration of LIM and the air gap. |
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