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Asymmetrical design method of grinding track profiles
Published in Maksym Spiryagin, Timothy Gordon, Colin Cole, Tim McSweeney, The Dynamics of Vehicles on Roads and Tracks, 2018
Over the past few decades, rail grinding has become increasingly important for the maintenance of railway system. Effective rail grinding could not only extend rail service life but also improve vehicle dynamic performance (Hull et al. 1977). The key to efficient rail grinding is to find a proper grinding rail profile to the specific line conditions. That means when dealing with straight track conditions, both grinding sides should be symmetrical. When it comes to curved track conditions, both grinding sides could be asymmetrical due to different curve-negotiation requirements. The basic requirements for smooth curve negotiation is to increase the equivalent conicity of the outer wheel and decrease the equivalent conicity of the inner wheel, so that when the wheelset negotiates the curve, flange contact could be greatly improved or even avoided. Although many scholars have contributed their works to rail profile design, such as Eric (Eric et al. 2002) and Wang (Wang et al. 2016), design of rail grinding profiles still has many problems to be solved due to the complexity of the field condition. To help accomplish this task, an asymmetrical design method for the determination of grinding track profiles is presented in the paper. The method chooses rolling radii difference (RRD) as the main object function and wheel-rail contact distribution as the secondary object function. With the help of numerical iterative method, the design problem could be solved efficiently. An example of rail profile design will be discussed in detail to show the effectiveness of the method.
Investigating the influence of rail grinding on stability, vibration, and ride comfort of high-speed EMUs using multi-body dynamics modelling
Published in Vehicle System Dynamics, 2019
Kai Xu, Zheng Feng, Hao Wu, Fu Li, Chenhui Shao
In addition, the vibration of high-speed trains can be aggravated by an increase in the equivalent conicity of the wheelset, which rises approximately linearly with wheel/rail wear and operating distance [11]. Therefore, the most direct solution to the vibration problem is to improve the wheel-rail interaction. Two improvement methods, wheel re-profiling and rail grinding, have been adopted in practice. Rail grinding is used to correct the rail profile to improve the wheel-rail interaction, control the generation and development of rail disease, extend the service life of the rail, reduce maintenance costs, and improve the safety and stability of train operation. However, there has been a lack of long-term investigations into the rail conditions of ground rails and the running performance of vehicles after the grinding has been performed.
Feature extraction method of abrasive belt wear state for rail grinding
Published in Machining Science and Technology, 2019
Meng Nie, Liu Yueming, Li Jianyong
Rail grinding is an important method for rail maintenance and is used to obtain the target profile by removing defects, such as corrugations, cracks, crushes and the decarburization layer of a new rail on the rail surface (Cuervo et al., 2015). Rail grinding can remove the rolling contact fatigue layer on the running surface of rail (Satoh and Iwafuchi, 2008), restrain the crack propagation on the rail surface, and repair the rail profile to improve the wheel-rail relationship; moreover, it prolongs the service life of the rail and enhances the operational security of the locomotive (Uhlmann et al., 2016). Wheel grinding has always been considered the main form of operation for traditional rail grinding processes (Gu et al., 2015). However, if the rail is ground by a grinding wheel, there could be a series of problems such as sparks splashes, grinding wheel fracture.
Suspension parameter optimal design to enhance stability and wheel wear in high-speed trains
Published in Vehicle System Dynamics, 2023
Xiangwang Chen, Longjiang Shen, Xiaoyi Hu, Guang Li, Yuan Yao
Figure 2 shows various wheel and rail profiles along with the corresponding equivalent conicity functions with respect to the wheelset lateral displacement. The equivalent conicity functions are calculated according to EN15302:2008 [24]. Different combinations of the wheel-rail profiles produce distinct contact geometries, leading to significant variations in the equivalent conicity curves. Rail grinding is a useful measure to correct the rail profile, control the generation and development of rail disease, and extend the rail service life. However, inadequate grinding accuracy can cause deviations from the standard profile, resulting in a poor wheel-rail matching relation. As depicted in Figure 2(b), the measured rail profile is excessively ground in the gauge corner, resulting in a wheel-rail contact equivalent conicity of about 0.06 at the wheelset lateral displacement of 3 mm when matched with the new wheel profile. This value is significantly lower than the standard wheel-rail matching equivalent conicity of about 0.18. Such a lower equivalent conicity can lead to the bogie hunting motion with a low frequency, approaching the natural frequency of the carbody. This can lead to carbody hunting instability [25,26], severely degrading ride comfort without exceeding the safety limit. Therefore, the lateral ride comfort of passengers at such a low equivalent conicity must be carefully addressed when designing suspension parameters. The Sperling index W, which is based on the measurement of carbody vibration acceleration, is widely used to quantify ride comfort and is defined as follows [27] where A is the acceleration amplitude in the frequency domain, f is the corresponding frequency, and F(f) is the frequency correction coefficient. For passenger vehicles, the limit values of ride comfort are 2.5, 2.75, and 3.0 for excellent, medium and qualified levels, respectively. Generally speaking, the excellent level is required during vehicle operation.