Uses of the Bezgin – Kolukırık Equations to estimate the highest dynamic impact force factors due to wheel flats

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Bezgin N. Ö.

20th International Wheelset Conference, Illinois, Amerika Birleşik Devletleri, 8 - 11 Mayıs 2023, ss.1-10, (Tam Metin Bildiri)

  • Yayın Türü: Bildiri / Tam Metin Bildiri
  • Basıldığı Şehir: Illinois
  • Basıldığı Ülke: Amerika Birleşik Devletleri
  • Sayfa Sayıları: ss.1-10
  • Açık Arşiv Koleksiyonu: AVESİS Açık Erişim Koleksiyonu
  • İstanbul Üniversitesi-Cerrahpaşa Adresli: Evet

Özet

Wheel flats is a major source of service and safety disruption along railway tracks. At the minimum, wheel flats generate noise and vibrations. As the sizes and the number of the wheel flats increase, the generated dynamic impact forces as the wheel flats repeatedly ram onto the surface of the railhead immediately create very high stresses at the wheel and rail contact interfaces, wheel running surface and the wheel rim, axle bearings, axles, rail head and the rail-tie bearing interface. The repeated and persistent occurrence of high dynamic impact forces on the railhead, the frequency of which relates to the train speed, the wheel diameter and the number of flats, advances the number, the depth and the density of the cracks and defects that are already forming along the railhead and the wheels, thereby gradually damaging the running surfaces of both the rails and the wheels in time. The end result is generally the fracture of the rail and/or the wheel, at one or many locations. Through an investigative collaboration, this paper presents the application of the Bezgin Method, developed to estimate the highest values of dynamic impact forces on railway tracks due to track and wheel roughness and the Bezgin – Kolukırık Equations K’B3 and K’B3,H  that estimate the highest values of the dynamic impact force factors due to wheel flats and compares their estimates with the estimates of advanced numerical models developed by SNCF Reseau. This study presents the variation of the effect of a wheel flat with wheel diameter and the static axle force and relates the highest value of the forces generated by a wheel flat with the length of the wheel flat. The findings in this study can aid the railway authorities to establish thresholds on wheel flats in relation to wheel diameter, train speed and static wheel force, in addition to track and rolling stock stiffness and flat length.