Demiryolu Taşıtlarında Kullanılan Fren Disklerinin Isı ve Malzeme Yönünden Değerlendirilmesi

Demiryolu taşıtı frenleme sistemleri, emniyetli şekilde durdurma, yavaşlatma ve uygun hızla hareketi sağlar. Yaygın olarak sürtünme etkisiyle mekanik frenleme gerçekleştirilir ve demiryolu taşıtları yüksek hıza uygun tasarlandığında fren disklerinin kullanımı, tek güvenli seçenektir. Fren diski boyutları ve ağırlığı, şasi altındaki alan, servis hızı gibi parametrelere göre çeşitlilik gösterir. Farklı malzemeler kullanıldığında ağırlık yarı yarıya varacak kadar azaltılabilmektedir. Frenleme esnasında mekanik enerji ısıya dönüşür. Çeşitli şekillerde ve boyutlarda tasarlanabilen soğutma kanatçıkları arasından akan hava, diskte konveksiyonla etkili soğutma sağlar. Diskte yerel olarak aşırı ısınan alanlar, fren diski malzemesinde yapısal değişikliğe, termal çatlak oluşumuna ve diğer hasarlara yol açar. Bu hasarlar, kontrol edilmediği ve ilerlediği, derin çatlaklar haline dönüştüğü takdirde zamanla disk kullanılamaz hale gelir. Demiryolu taşıtı fren diski imalinde yaygın ve geleneksel olarak dökme demir (lamelli, vermiküler, küresel grafitli) kullanılır; ayrıca yüksek alaşımlı dökme demirler, dökme ve dövme çelik. Fren diski çeliklerinin kırılma tokluğunu artırmak ve aşınma dirençlerini yükseltmek için bileşene çeşitli alaşım elementleri eklenebilir. Ayrıca özellikle alüminyum ve seramik matrisli kompozit malzemelerin kullanımı da söz konusudur, böylelikle istenilen özelliklerde ve oldukça hafif tren fren diski üretilebilir. Bu çalışmada fren disk yapısı ve soğutma kanatçıkları, frenlemede ısı oluşumu, transferi, sıcaklık gradyanları ve sıcak bölgelerde oluşan sorunlar, termik çatlaklar, fren disklerinde kullanılan ve kullanılabilecek malzemeler hakkında bilgi verilmiştir.

Anahtar Kelimeler:

Demiryolu, fren diskleri, malzeme, ısı, ısıl hasarlar

Assessment of Brake Discs Used Railway Vehicles in terms of Heat and Material

Railway vehicle brake systems provides safely stopping, slowing and its movement at the appropriate speed. Mechanical braking is commonly performed by the effect of friction, and the use of brake discs is the only reliable option when railway vehicle is designed for high speed. The dimensions and weight of the brake discs, the area under the chassis, the service speed of the train, etc. varies as it is designed according to the parameters. The weight can be reduced by up to half, when different materials are used. During braking, mechanical energy is converted into heat. The air flowing between the ventilation vanes, which can be designed in various shapes and sizes, provides effective convective cooling in the disc. Locally overheated areas cause structural changes in the brake disc material, thermal crack formation and other damage. If these damages are not controlled and progress and turn into deep cracks, the disc becomes unusable over time. Lamellar, vermicular or spheroidal graphite cast iron is commonly and traditionally used in the manufacture of railway vehicle brake discs. Also cast irons with special compositions, as well as casting and forging steel. Various alloying elements can be added to the composition to increase the fracture toughness and wear resistance of steels to be used as brake disc material. There is also the use of composite materials especially aluminium or ceramic matrix composites thus, a train brake disc desired property and very light can be produced. In this study, information is given about brake disc structure and cooling vanes, heat generation and transfer in braking, heat gradients and problems in hot regions, thermal cracks, materials used and can be used in brake discs.

Keywords:

Railway, brake discs, material, heat, thermal damages,

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Sharma, R.,C., Dhingra, M. ve Pathak, R., K. (2015). Braking Systems in Railway Vehicles. (IJERT) International Journal of Engineering Research & Technology, Vol.4, Issue.01, 206-211.
Hasegewa, I. ve Uchida, S. (1999). Braking systems. Japan Railway & Transport Review 20, 52-59.
Grivc, U. ve Muhič, S. (2018). Numerical optimization of brake discs for railway vehicles. Journal of Energy Technology, JET., Vol.11, Issue.3, Type.1.01, 11-25.
Research Designs and Standarts Organization. (2017). Specification for Standardized Brake Disc for LHB Coaches (RDSO/2017/CG-02). Manak Nagar Luckdown, RDSO.
Li, J., Li, H., Jiao, B., Lv, B., Chen, D. ve Gu, L. (2013). Development of cast steel for brake discs of high-speed train. Applied Mechanics and Materials, Vol.419, 370-375.
Brake Discs, Kovis Group, (2021, 12 Mayıs). Erişim adresi https://www.kovis-group.com/kovis/en/products/brake-discs/.
Tirovic, M. (1998). Development of a wheel mounted disc brake for a high-speed train. Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit,Vol.212, 113-121.
Tirovic, M. ve Galindo-Lopez, C.H. (2008). Convective heat dissipation from a wheel-hub mounted railway brake disc. Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit,Vol.222, 355-365.
Wang, Z., Han, J., Liu,X., Li, Z., Yang, Z. ve Chen, E. (2019). Temperature evolution of the train brake disc during high-speed braking. Advances in Mechanical Engineering, Vol.11(1), 1-10.
Desplanques, Y., Roussette, O., Degallaix, G., Copin, R. ve Berthier, Y. (2007). Analysis of tribological behaviour of pad–disc contact in railway braking Part 1. Laboratory test development, compromises between actual and simulated tribological triplets. Wear, Vol.262, 582-591.
Galindo-Lopez, C. H. (2009). Optimisation of convective heat dissipation from ventilated brake discs. Doktora Tezi, Cranfield Üniversitesi, Birleşik Krallık.
Tirovic, M. ve Galindo-Lopez, C.H. (2012). Maximising heat dissipation from ventilated wheel-hub-mounted railway brake discs. Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit,Vol.227(3), 269-285.
Tirovic. M. (2009). Energy thrift and improved performance achieved through novel railway brake discs. Applied Energy, Vol.86, 317–324.
Nejat, A., Aslani, M., Mirzakhalili, E. ve Najian Asl, R. (2011). Heat transfer enhancement in ventilated brake disk using double airfoil vanes. Journal of Thermal Science and Engineering Applications, Vol.3(4), 045001.
Sakamoto, H. (2015). Heat convection and design of brake discs. Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit,Vol.218, 203-212.
Adamowicz, A. ve Grzes, P. (2011). Analysis of disc brake temperature distribution during single braking under non-axisymmetric load. Applied Thermal Engineering, Vol.31 (6-7), 1003-1012.
Dufrénoy, P. ve Weichert, D. (2003). A thermomechanical model for the analysis of disc brake fracture mechanisms. Journal of Thermal Stresses, Vol.26(8), 815-828.
Li, Z., Han, J., Yang, Z. ve Li, W. (2015). Analyzing the mechanisms of thermal fatigue and phase change of steel used in brake discs. Engineering Failure Analysis, Vol.57, 202-218.
Panier, S., Dufrénoy, P. ve Weichert, D. (2004). An experimental investigation of hot spots in railway disc brakes. Wear, Vol.256, 764-773.
Balcı, M. N. (2020). Fren disk-balata mekanizmasının üç boyutlu gerilme analizi. Konya Journal of Engineering Sciences, Vol.9, No.1, 62-84.
Yevtushenko, A., Kuciej, M. ve Wasilewski, P. (2019). Experimental study on the temperature evolution in the railway brake disc. Theoretical & Applied Mechanics Letters, Vol.9, 308-311.
Goo, B. ve Lim, C. (2012). Thermal fatigue of cast iron brake disc materials. Journal of Mechanical Sciense and Technology, Vol.26(6), 1719-1725.
Kim, D.J., Seok, C.S., Koo, J.M., We, W.T., Goo, B.C., ve Won, J.I. (2010). Fatigue life assessment for brake disc of railway vehicle. Fatigue & Fracture of Engineering Materials & Structures, Vol.33, 37–42.
Wang, Z., Han, J., Domblesky, J. P., Li, Z., Fan, X. ve Liu, X. (2019). Crack propagation and microstructural transformation on the friction surface of a high-speed railway brake disc. Wear, Vol.428–429, 45–54.
Fan, S., Zhang, L., Cheng, L., Zhang,J., Yang, S. ve Lui, H. (2011). Wear mechanisms of the C/SiC brake materials. Tribology International, Vol.44, 25-28.
Xiao, X., Yin, Y., Bao, J., Lijian, L. ve Feng, X. (2016). Review on the friction and wear of brake materials. Advances in Mechanical Engineering, Vol.8(5), 1-10.
Sakamoto, H. ve Hırakawa K. (2005). Fracture analysis and material improvment of brake discs. JSME(The Japan Society of Mechanical Engineering) International Journal, Series:A Vol.48 No.4, 458-464.
Gigan, G., Norman, V., Ahlstörm, J. ve Vernersson, T. (2019). Thermomechanical fatigue of grey cast iron brake discs for heavy vehicles. Proceedings of the Institution of mechanical engineers. Part D, Journal of Automobile Engineering, Vol.233(2), 453-467.
Er, O. ve Ünel, E. (2013). Raylı araçların boji donanımında kullanılan dökme demir ürünler. 2. Uluslararası Raylı Sistemler Mühendisliği Sempozyumu (ISERSE’13), Karabük, Türkiye, 9-11 Ekim.
Abebe, L., Nallamothu, R.B., Subrahmanyam, K.H.S., Nallamothu, S.K., Nallamothu A.K. (2016). Thermal analysis of disc brake made of different materials. SSRG International Journal of Mechanical Engineering, Vol.3(6), 5-9.
Karatay, B. ve Hasırcı, H. (2018). Üretim koşullarının vermiküler grafitli dökme demirin mikro ve makro yapısal özelliklerine etkileri. Fen Bilimleri Dergisi GU J Sci, Part C:Tasarım ve Teknoloji, Vol.6(4), 887-897.
Šamec, B., Potrcˇ, I. ve Šraml, M. (2011). Low cycle fatigue of nodular cast iron used for railway brake discs. Engineering Failure Analysis, Vol.18, 1424-1434.
Wu, D., Wang, F., Li, C., Zheng, Y. ve Shen, W. (2018). Effect of temperature on oxidation behavior of Cr–Mo–V steel with different Cr contents for high-speed train brake discs. 9th International Symposium on High-Temperature Metallurgical Processing, Arizona, ABD, 11-15 Mart.
Harada, N., Takuma, M., Tsujikawa, M. ve Higashi, K. (2013). Effects of V addition on improvement of heat shock resistance and wear resistance of Ni–Cr–Mo cast steel brake disc. Wear, Vol.302, Issues.1-2, 144-1452.
Brake discs and pads. (2014). Munich: Knorr-Bremse s. 2.
Rak, Z. S. (2013). CMC material for train brake systems. Journal of Advances in Applied Ceramics, 99(6), 270-273, http://dx.doi.org/10.1179/096797800681072.
Nong, X.D., Jiang, Y.L., Fang, M., Yu, L. ve Liu, C.Y. (2017). Numerical analysis of novel SiC3D/Al alloy co-continuous composites ventilated brake disc. International Journal of Heat and Mass Transfer, Vol.108, 1374-1382.