Experimental study of natural frequencies and forms of the rail oscillations

The article considers the problem of assessing the stability of the continuously welded track at its temperature elongation and proposes a method for this assessment by comparing the actual temperature of fastening the rail strings with the standard one. A method for determining the actual temperature of rail fastening is presented, which consists in measuring its temperature and natural vibration frequencies, followed by an analysis of the dependence of the change in the natural frequency of the rail head in the transverse direction on the magnitude of the longitudinal force applied to the rail. The methodology of the tests performed at the bench and section of the continuously welded track of the Ozerskaya branch of the Moscow railway is described. The essence of the technique is to determine the values of natural vibrations using various measuring instruments (strain gauges, vibration transducers, sound level meters) at different values of the longitudinal force applied to the rail. Natural vibrations were excited by hitting the rail head in the transverse direction. A comparative analysis of the forms and frequencies of natural vibrations of the rail head is carried out according to the test results in bench and operational area conditions. It was found that the closest convergence of the vibration frequencies of the rail head in the transverse direction corresponds to the first mode of vibration. During bench tests, the dependence of the frequency change of the first form of natural vibrations of the rail head in the transverse direction on the magnitude of the longitudinal force applied to the rail was determined. According to the results of a comparative analysis of the results of measurements of the natural frequencies of rail oscillations, the possibility of using a sound level meter or similar measuring instruments for their registration was established. The calculation of the actual temperature of the rail fastening is also given on the example of the section of the continuously welded track of the Ozerskaya branch of the Moscow railway and its compliance with the normative for this region is established.

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