Research On The Suppression Methods Of Corrugation On Tight Metro Curved Tracks And Model Optimization

Urban Rail Transit has been developed rapidly due to its environmental friendliness,high efficiency and convenience,safety and comfort.But in the meanwhile,many problems of wheel-rail systems,especially the rail corrugation problem,bother people.Rail corrugation has brought many serious problems such as vibration,noise and parts damage.So,it needs to be solved urgently.Rail grinding is a reliable method but it is passive.Therefore,it is of practical significance to find active ways to suppress the occurrence of corrugation before it occurs.There are many curved track sections in subway lines,and frequent traction and braking are more likely to cause rail corrugation.Here,the author takes the metro corrugation on tight curved tracks as the research object.Based on the theory method that the friction-induced self-excited vibration causes rail corrugation,the ABAQUS software is used to establish finite element models of wheelset-track systems,which will be executed with the complex eigenvalue analysis and the transient dynamic analysis.The countermeasures of eliminating or suppressing corrugation are explored from the aspects of wheelset structures and installing rail vibration absorbers.The optimization of the model is also explored from the aspect of the simulation ways of rail fastener systems.The main contents and results of this paper are as follows:(1)Taking the wheel with double S-type web as the research object,which is divided into the positive double S-type web and negative double S-type web according to the different bending directions of the webs.And the corresponding finite element models of the wheelset-track system on a sharp curved track with ordinary short sleepers are established.The author regards the web bending direction,bending size and web thickness as impact factors,and uses the complex eigenvalue method to explore their effects on rail corrugation in the frequency domain.A single S-type web wheel model and a straight-type web wheel model are built as comparison groups.The results show that the positive double S plate wheel is a non-corrugated wheel,and the bending size and plate thickness have no significant influence on corrugation.While the negative double S plate wheel tends to cause rail corrugation,and the greater the bending degree,the more easily it causes friction-induced self-excited vibration of the wheelset-track system.In addition,for the positive double S plate wheel without corrugation,a transient dynamic model of the wheelset-track system is established to obtain its dynamic response during the wheel running on a rail.The calculation results show that the vertical vibration accelerations and contact normal forces of the inner and outer rails are close to each other.Hence,the positive double S web without corrugation has been double-verified in the time domain.The research will help railway wheels design engineers with a guiding advice for designing and choosing wheels.(2)From the perspective of installing rail vibration absorbers,finite element models of wheelset coupled with ordinary short sleeper tack containing two rail vibration absorbers are established,which are named as the mass-type rail vibration absorber and the layered vibration absorber.The two types of rail vibration absorbers are composed of a damping layer and a rigid layer.The main difference lies in the simulation ways of the damping layer.Under the operating condition of tight curved tracks,the corrugation suppression effects of the two rail vibration absorbers are studied through the complex eigenvalue analysis.The role of the damping layer is emphasized,and the regression prediction algorithm is utilized to find the critical effect value of the material properties of the damping layer on corrugation.The results show that when the properties of damping layer are selected appropriately,the two kinds of rail vibration absorbers have a certain inhibitory effect on corrugation.Particularly,for the layered vibration absorber,its inhibition effect of corrugation increases as the elastic modulus E of the damping layer decreases.According to the regression model,it is predicted that when E drops below 40 MPa,the first-order unstable vibration of the system will be suppressed;when E continues to drop to 26.15 MPa,the friction-induced self-excited vibration will be completely suppressed,that is,the rail corrugation is eliminated at this time.This research can provide a certain reference for the design and installation of rail vibration absorbers.(3)Finite element models of wheelset coupled with integral slab track with sharp curve are established.Starting from the idea of model optimization,considering the different ways of simulating rail fasteners,the traditional spring-damping fastener model and the new rail pad fastener model are built.And employing the complex eigenvalue method to calculate the corresponding frequencies of the friction-induced self-excited vibration.Meanwhile,the ordinary short sleeper track is used as the comparison group to compare and analyze the influence of the two track models on the prediction of corrugation.The results show that the two types of track with the spring-damping fasteners both obtain the predicted frequency of corrugation at about 500 Hz.And the integral slab track model with the rail pad fastener predicts the corrugation frequency to be 239.98 Hz,which is closer to the measured frequency of 333 Hz.Hence,the optimization of the corrugation prediction model is well realized.