Experimental analysis of the modal characteristics of rail fastening clips

Abstract

It is usually difficult to obtain the modal characteristics of the rail fastening clip analytically owing to its complex spatial structure and operating environments. Therefore, experimental modal testing is frequently adopted to identify the modal characteristics of rail fastening clips. This study takes the SKL 15 clip of the Vossloh 300-1 fastening system as the research object to analyse the following three aspects in great detail: (1) Locations of the measurement points are reasonably designed to capture all modes of the clip in the frequency range 0–1000 Hz. (2) The appropriate sensors are selected for the clip in different operating situations by comparing the measured results of three kinds of sensors, namely the accelerometer, laser vibrometer and sound pressure sensor. In addition, the test results suggest that the accelerometer which has a strong anti-disturbance ability in an ambient environment is recommended to be chosen in a noisy environment while the laser vibrometer and sound pressure sensor which have no added mass to the tested structures may be used in an indoor environment with suitable temperature and low noise. (3) In order to eliminate the effect of the additional mass on the modal characteristics of the clip, the accelerometer is recommended to be installed at the rear end of the side leg of the clips in the experimental modal test.

Development of a new and modification of existing elastic clips for rails fastening

“…Any defect or damage in any of the fastening system components can lead to a change in track geometry, wear of the rail, and loosening or failure of the rail fastening point [1,9]. For example, permanent deformation of the clips, caused by material fatigue, often reduces the fastening force or, in the latter case, breaks the clip (Figure 3.a) [10][11][12][13][14][15][16][17][18][19][20]. This damage can lead to a loss of structural integrity between the rail and sleeper.…”

“…This damage can lead to a loss of structural integrity between the rail and sleeper. Thus, the fastening system loses not only the fundamental property of stability and safety but also the property of elasticity, which can lead to the deterioration of the ballast bed and layers of the track substructure [14,21]. The problems related to the track ballast bed made of stone aggregate and an overview of its numerical modelling are explained in detail in [22].…”

“…Therefore, the second research group includes the approach for the dynamic strength assessment of the clips from the frequency domain perspective [14,19,74]. In most cases, the clip is in direct contact with the rail and may vibrate in resonance with the rail, which can damage the clip, reduce the required fastening force magnitude force, or eventually cause the breakage of the clip [19,74,75].…”

“…Many field measurements have shown that clip damage is mainly caused by vibrations with frequencies lower than 1000 Hz, which are generated by the wheel-rail interaction [14]. However, a study on the dynamic parameters of the clip from the frequency domain perspective states that the frequency range in which the natural frequencies of the clip should be investigated is 0-1000 Hz [14,74], and the study [19] indicates up to 2000 Hz. Previous research studies that analysed the fastening system, including all components, if noise is ignored, were performed in the range of 100-1000 Hz [71,73,76].…”

“…Therefore, the relationship between the clip's and rail's natural frequencies in response to the dynamic forces generated during rail-wheel contact must be understood. Therefore, Sun et al [14] reported that the first important step in clip analysis is determining its modal parameters, including the natural modes and frequencies. Moreover, procedures that avoid clip and rail resonance should be considered in the early stages of clip development [14].…”