International Journal of Railway Research
Iran University of Science & Technology
Sat, Jul 27, 2024
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Volume 10, Issue 2 (12-2023)
IJRARE 2023, 10(2): 1-8 |
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Belyaev V. Evaluation of prevailing longitudinal forces in the couplings of electric trains. IJRARE 2023; 10 (2) :1-8
URL: http://ijrare.iust.ac.ir/article-1-321-en.html
URL: http://ijrare.iust.ac.ir/article-1-321-en.html
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Abstract: (539 Views)
Railway administrations used to have no requirements for the fatigue strength and endurance of electric trains’ couplings. However, mass decommissioning of ICE1 trains in Germany due to cracked couplings and two coupling breakages in an electric train in Russia happened. Forces transferred through couplings are low-levelled which are not compared with couplings’ yield stress. Consequently, the abovementioned problems arise from fatigue damage. The need for detection of forces in electric trains’ couplings, the development of fatigue strength requirements, and test methodologies became obvious.
In 2022, VNIIZHT assessed forces into couplings of different electric trains under low and high temperatures; mileage was 9 600 km. Maximal recorded forces under compression and tension were +117/ 128 kN – far less than the yield stress of electric train couplings (+1500/-1000 kN). It verifies assumed fatigue damage.After data processing, the statistical distribution of peak-to-peak amplitudes of forces in couplings per run unit and per service life of an electric train (40 years) with the account of their average annual run (130 and 170 thousand km for electric trains with constructional speeds of 120 and 160 km/h, respectively) was derived. The impact of forces of different levels on fatigue strength was calculated with respect to fatigue curves, and the values of peak-to-peak amplitudes were set to 4 (normalized couplings) and 5 (quenched and tempered couplings).
Endurance under cyclic loading depends not only on the quantity of amplitudes of forces at each level but also on the asymmetry coefficient of the load cycle R = Pmin/Pmax. The developed methodology contains specific quantities of load cycles depending on the force amplitude and asymmetry coefficient of load cycle R.
In 2022, VNIIZHT assessed forces into couplings of different electric trains under low and high temperatures; mileage was 9 600 km. Maximal recorded forces under compression and tension were +117/ 128 kN – far less than the yield stress of electric train couplings (+1500/-1000 kN). It verifies assumed fatigue damage.After data processing, the statistical distribution of peak-to-peak amplitudes of forces in couplings per run unit and per service life of an electric train (40 years) with the account of their average annual run (130 and 170 thousand km for electric trains with constructional speeds of 120 and 160 km/h, respectively) was derived. The impact of forces of different levels on fatigue strength was calculated with respect to fatigue curves, and the values of peak-to-peak amplitudes were set to 4 (normalized couplings) and 5 (quenched and tempered couplings).
Endurance under cyclic loading depends not only on the quantity of amplitudes of forces at each level but also on the asymmetry coefficient of the load cycle R = Pmin/Pmax. The developed methodology contains specific quantities of load cycles depending on the force amplitude and asymmetry coefficient of load cycle R.
Keywords: Electric train couplers, Normal operation forces, Fatigue resistance requirements, Testing methodology
Type of Study: Research |
Subject:
Rolling Stock
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