Abstract
To estimate the rail axial force of high-speed railway ballastless track, the reasonable index without complex measuring or error correction process is proposed. Taking the ballastless track structure in high-speed railway as the research object, the wave motion of periodic ballastless track is studied using the wave finite element method. It is found that some standing wave modes are linearly correlated with the rail axial force and thus can be considered as the basic indices for rail axial force estimation. A further in situ experiment according to the modal test method is performed and the feasibility of different wave modes for estimating rail axial force is discussed. Experiment results show that the lateral wave mode coincides well with the theoretical result while there is a large difference for the vertical wave mode. To explicate the difference, the temperature-dependent properties of the fastening are tested additionally. Parametric analysis shows that the frequency shift of vertical wave mode is greatly affected by the fastening temperature-dependent characteristics including the rail pad, elastic pad, and fastener clamping force, while the frequency shift of lateral wave mode is mainly determined by the rail axial force.
Highlights
Continuous welded rail (CWR) has been widely applied in high-speed railway lines; excessive stress in the rail can be generated with large temperature variation, causing rail buckling or breaking
This paper studied the rail axial force estimation in high-speed railway ballastless track theoretically and experimentally
(1) The flexural wave modes of ballastless track are sensitive to the rail axial force
Summary
Continuous welded rail (CWR) has been widely applied in high-speed railway lines; excessive stress in the rail can be generated with large temperature variation, causing rail buckling or breaking. [13] and Kjell et al [14] evaluated the rail axial force by measuring the flexural wavelength of rail under a fixed excitation frequency by laser vibrometer and accelerometers In this method, some fastenings must be removed, and high precision is required. The above characteristics provide more feasibility to estimate the rail axial force accurately in high-speed railway ballastless track by using the vibration technique. This paper presents the theoretical and experimental study on the relative rail axial force estimation in periodic ballastless track structure based on the wave modes.
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