Relation between reliability and availability of railway vehicles

Pouzdanost i raspoloživost železničkih vozila su značajne karakteristike zbog čega je vrlo važno utvrđivanje i njihovog međusobnog odnosa. U radu je dat prikaz mogućnosti određivanja uticaja pouzdanosti železničkog vozila na njegovu raspoloživost na primeru koji uzima u obzir realne vrednosti tih karakteristika za uslove "Železnica Srbije". Potvrđen je veliki značaj ostvarenja visoke pouzdanosti voznih sredstava u uslovima njihovog održavanja sa malom efikasnošću. To, sa svoje strane, upućuje na obavezu "Železnica Srbije" da, pored stalnog podizanja nivoa efikasnosti održavanja prilikom modernizacije postojećih i nabavke novih voznih sredstava insistira na visokoj pouzdanosti komponenata i sistema u celini.Reliability, availability and their mutual relationship are very important characteristics of railway vehicles. This paper presents how to determine the influence of railway vehicle reliability on its availability, using the real worked example with real values of these characteristics, for Serbian Railway conditions. Significant importance in achieving high reliability under the conditions of maintaining characteristics with small efficiency is confirmed. That indicates an obligation of Serbian Railways to insist on high reliability of components and the system as a whole, apart from constant increase of maintenance level efficiency within modernization of existing and purchase of new rolling stock

The influence of the change of the fatigue strength distribution parameters on the railway vehicle solid wheel reliability

U radu je izvršena analiza uticaja matematičkog očekivanja i standardnog kvadratnog odstupanja trajne dinamičke čvrstoće materijala (kao kritičnog napona) na pouzdanost monoblok točka železničkog vozila pod dejstvom mehaničkih opterećenja. Za proračun pouzdanosti korišćena je metodologija koja podrazumeva određivanje idealnih radnih napona u kritičnoj oblasti točka na osnovu raspodela opterećenja dobijenih u eksploataciji i izračunavanje pouzdanosti na osnovu definisanih raspodela radnih i kritičnih napona.This paper analyzes the influence of the material limit fatigue strength mathematical expectation and standard squaring deviation (as a critical stress) on the railway vehicle solid wheel reliability under the affect of the mechanical loads. Reliability calculation was conducted using the methodology which includes the determination of the ideal working stresses in the critical area of the wheel according to the load distributions obtained during operation and the reliability calculation according to the defined working and critical stresses distributions

The influence of the change of the fatigue strength distribution parameters on the railway vehicle solid wheel reliability

U radu je izvršena analiza uticaja matematičkog očekivanja i standardnog kvadratnog odstupanja trajne dinamičke čvrstoće materijala (kao kritičnog napona) na pouzdanost monoblok točka železničkog vozila pod dejstvom mehaničkih opterećenja. Za proračun pouzdanosti korišćena je metodologija koja podrazumeva određivanje idealnih radnih napona u kritičnoj oblasti točka na osnovu raspodela opterećenja dobijenih u eksploataciji i izračunavanje pouzdanosti na osnovu definisanih raspodela radnih i kritičnih napona.This paper analyzes the influence of the material limit fatigue strength mathematical expectation and standard squaring deviation (as a critical stress) on the railway vehicle solid wheel reliability under the affect of the mechanical loads. Reliability calculation was conducted using the methodology which includes the determination of the ideal working stresses in the critical area of the wheel according to the load distributions obtained during operation and the reliability calculation according to the defined working and critical stresses distributions

Relation between reliability and availability of railway vehicles

Pouzdanost i raspoloživost železničkih vozila su značajne karakteristike zbog čega je vrlo važno utvrđivanje i njihovog međusobnog odnosa. U radu je dat prikaz mogućnosti određivanja uticaja pouzdanosti železničkog vozila na njegovu raspoloživost na primeru koji uzima u obzir realne vrednosti tih karakteristika za uslove "Železnica Srbije". Potvrđen je veliki značaj ostvarenja visoke pouzdanosti voznih sredstava u uslovima njihovog održavanja sa malom efikasnošću. To, sa svoje strane, upućuje na obavezu "Železnica Srbije" da, pored stalnog podizanja nivoa efikasnosti održavanja prilikom modernizacije postojećih i nabavke novih voznih sredstava insistira na visokoj pouzdanosti komponenata i sistema u celini.Reliability, availability and their mutual relationship are very important characteristics of railway vehicles. This paper presents how to determine the influence of railway vehicle reliability on its availability, using the real worked example with real values of these characteristics, for Serbian Railway conditions. Significant importance in achieving high reliability under the conditions of maintaining characteristics with small efficiency is confirmed. That indicates an obligation of Serbian Railways to insist on high reliability of components and the system as a whole, apart from constant increase of maintenance level efficiency within modernization of existing and purchase of new rolling stock

Temperature and stress state of the block-braked solid wheel in operation on Yugoslav railways

Termičko opterećenje monoblok točka železničkog vozila kočenog papučama je dominantno u odnosu na ostale vrste opterećenja. To opterećenje, koje je uglavnom posledica dugotrajnog kočenja na padovima u cilju održavanja brzine je osnovni uzrok pojave pukotina na površini kotrljanja točka i, kao krajnja posledica, loma točka. U radu su dati rezultati proračunske analize termičkog opterećenja monoblok točka na odabranoj karakterističnoj deonici pruge Jugoslovenskih železnica. Proračuni temperaturnih i naponskih stanja točka rađeni su pomoću metode konačnih elemenata.Thermal load of the block-braked solid wheel railway vehicles is dominant on the other types of loads. This load, which is mainly consequence of long-term braking on downgrades for maintaining the defined constant speed purpose, is the main cause of occurrence of cracks on treads of wheel and finally fractures of wheel. The paper gives the analysis calculation results of the thermal load of the railway vehicle block-braked solid wheel on characteristic selected line on Yugoslav Railways network. Thermal analysis was done using the finite elements method, which was also used for obtaining wheel temperature and stress states in the simulated operation conditions

Experimental verification of auto carrier car strength calculation

U radu je dat proračun i eksperimentalna analiza naponskog stanja noseće strukture vagona za prevoz automobila. Proračunom je obuhvaćena statička i dinamička analiza noseće strukture, kao i određivanje torzione krutosti primenom metode konačnih elemenata. Analiza čvrstoće noseće strukture je obuhvatila i opterećenje pod dejstvom bočne sile nastale usled ubrzanja od 0,1 g. Analizirana je četvrtina vagona sa bočnim vratima, kao najslabiji deo strukture. Ispitivanjem je obuhvaćena noseća struktura vagona koja se sastoji od postolja, bočnih stranica i dve pokretne platforme, bez čeonih i bočnih vrata kao i krova. Naponi su mereni pomoću mernih traka na 120 mernih mesta, od kojih su pojedina omogućavala merenje napona u sva tri pravca. Rezultati merenja pokazuju da su naponi u svim slučajevima opterećenja značajno ispod dozvoljenih. Zaostali naponi su bili u dozvoljenim granicama. Ugibi noseće strukture su bili veoma mali i nisu prešli 0,6 ‰ rastojanja osa svornjaka, što je značajno ispod dozvoljene vrednosti.In this paper a calculation method and experimental analyses of auto carrier car bearing structure strength are shown. The calculation includes both the static and dynamic analyses of the bearing structure; also the determination of the car body torsion rigidity calculation has been performed with the programming package based on Finite Element Method. The analyses of the bearing structure strength for the load case due to the car lateral inertia forces at lateral acceleration of 0,1.g has also been included. The calculation covered one quarter of the wagon with two doors as the weaker ones. The object tested was the auto carrier car composed of the underframes, sidewalls and two mobile upper platforms without side and front doors and without roof. Stresses were measured by the strain-gauge method on 120 measuring points. Some of them were connected to form strain gauges in three directions thus enabling the estimation of principal stresses. The measuring results show that the stress conditions in all load cases are remarkably under the allowable stresses. The residual stresses were in acceptable limits. Bearing structure deflections were very small and did not exceed 0,6‰ from the centre pin distance, which is well below allowable value

Experimental verification of auto carrier car strength calculation

U radu je dat proračun i eksperimentalna analiza naponskog stanja noseće strukture vagona za prevoz automobila. Proračunom je obuhvaćena statička i dinamička analiza noseće strukture, kao i određivanje torzione krutosti primenom metode konačnih elemenata. Analiza čvrstoće noseće strukture je obuhvatila i opterećenje pod dejstvom bočne sile nastale usled ubrzanja od 0,1 g. Analizirana je četvrtina vagona sa bočnim vratima, kao najslabiji deo strukture. Ispitivanjem je obuhvaćena noseća struktura vagona koja se sastoji od postolja, bočnih stranica i dve pokretne platforme, bez čeonih i bočnih vrata kao i krova. Naponi su mereni pomoću mernih traka na 120 mernih mesta, od kojih su pojedina omogućavala merenje napona u sva tri pravca. Rezultati merenja pokazuju da su naponi u svim slučajevima opterećenja značajno ispod dozvoljenih. Zaostali naponi su bili u dozvoljenim granicama. Ugibi noseće strukture su bili veoma mali i nisu prešli 0,6 ‰ rastojanja osa svornjaka, što je značajno ispod dozvoljene vrednosti.In this paper a calculation method and experimental analyses of auto carrier car bearing structure strength are shown. The calculation includes both the static and dynamic analyses of the bearing structure; also the determination of the car body torsion rigidity calculation has been performed with the programming package based on Finite Element Method. The analyses of the bearing structure strength for the load case due to the car lateral inertia forces at lateral acceleration of 0,1.g has also been included. The calculation covered one quarter of the wagon with two doors as the weaker ones. The object tested was the auto carrier car composed of the underframes, sidewalls and two mobile upper platforms without side and front doors and without roof. Stresses were measured by the strain-gauge method on 120 measuring points. Some of them were connected to form strain gauges in three directions thus enabling the estimation of principal stresses. The measuring results show that the stress conditions in all load cases are remarkably under the allowable stresses. The residual stresses were in acceptable limits. Bearing structure deflections were very small and did not exceed 0,6‰ from the centre pin distance, which is well below allowable value

Temperature and stress state of the block-braked solid wheel in operation on Yugoslav railways

Termičko opterećenje monoblok točka železničkog vozila kočenog papučama je dominantno u odnosu na ostale vrste opterećenja. To opterećenje, koje je uglavnom posledica dugotrajnog kočenja na padovima u cilju održavanja brzine je osnovni uzrok pojave pukotina na površini kotrljanja točka i, kao krajnja posledica, loma točka. U radu su dati rezultati proračunske analize termičkog opterećenja monoblok točka na odabranoj karakterističnoj deonici pruge Jugoslovenskih železnica. Proračuni temperaturnih i naponskih stanja točka rađeni su pomoću metode konačnih elemenata.Thermal load of the block-braked solid wheel railway vehicles is dominant on the other types of loads. This load, which is mainly consequence of long-term braking on downgrades for maintaining the defined constant speed purpose, is the main cause of occurrence of cracks on treads of wheel and finally fractures of wheel. The paper gives the analysis calculation results of the thermal load of the railway vehicle block-braked solid wheel on characteristic selected line on Yugoslav Railways network. Thermal analysis was done using the finite elements method, which was also used for obtaining wheel temperature and stress states in the simulated operation conditions

Experimental and numerical determination of tube collision energy absorbers characteristics

Razvoj apsorbera energije sudara je jedna od neophodnih mera pasivne zaštite putničkih vagona. Uloga pasivne zaštite je da posledice sudara svede na najmanju moguću meru. Apsorber razvijan u ovom radu sastoji se od čeličnih bešavnih cevi u kvalitetu P235T1 i konusne čaure napravljene od čelika za poboljšanje u kvalitetu C45E. Tokom sudara provlačenjem cevi kroz konusnu čauru dolazi do redukcije - smanjenja prečnika cevi pri čemu se troši energija. U radu su analizirani rezultati dobijeni numeričkim simulacijama i dinamičkim ispitivanjima cevnih apsorbera kinetičke energije sudara putničkih vagona. Glavni cilj rada je uspostavljanje korelacije rezultata dobijenih numeričkim simulacijama i eksperimentalnim istraživanjima. Korišćenjem karakterističnih parametara dobijenih tokom kvazi-statičkih, dinamičkih ispitivanja i numeričkih simulacija, definisane su vrednosti ključnih parametara koje se mogu koristiti za buduća ispitivanja cevnih apsorbera ovog tipa pri brzinama većim od 20 km/h. Numeričke simulacije se mogu koristiti u fazi razvoja apsorpcionih elemenata dok je za konačnu ocenu prototipa neophodno uraditi dinamička ispitivanja.Development of collision energy absorbers is one of the necessary measures for passive safety of passenger coaches. The purpose of passive safety is to minimize the collision consequences for passengers. The collision absorber developed in this work consisted of a low carbon seamless steel tube and conical bush fabricated from quench and tempered carbon steel. During collision, the seamless tube is compressed into a bush with a reduced diameter. In this paper, the analysis of results is obtained by numerical simulations and dynamic investigation of tube absorbers of kinetic collision energy of passenger coaches. The research focuses on correlations between numerical and dynamic test results. Using the characteristic parameters obtained by the dynamic tests and numerical simulations, values for key numerical parameters have been defined, which can be used for further investigations of tube shrinking absorber. Numerical simulations should be used in the developing phase of a prototype, while for the final verification it is necessary to do dynamic (impact) test

Validacija modela železničkog vozila sa trodelnim obrtnim postoljem

Za analizu kvazistatičkog i dinamičkog ponašanja železničkih danas se sve više upotrebljavaju različiti matematički-numerički modeli. Jedno od osnovnih pitanja koje se postavlja prilikom modeliranja mehaničkih sistema je u kojoj meri razvijeni model može tačno opisati realni sistem. U ovom radu je prikazan model železničkog vozila za prevoz rude gvožđa sa povećanom osovinskom nosivošću i izvršena je validacija modela saglasno preporukama UIC-a. Za ocenu saglasnosti modela i realnog sistema poređena su ubrzanja u vertikalnoj i horizontalnoj ravni, vertikalne i bočne sile u kontaktu točak šina, za prazno i natovareno vozilo koje se kreće na pravcu i u krivini. Dobijeni rezultati pokazuju veliku saglasnost rezultata dobijenim eksperimentalnim ispitivanjem i simulacijom dinamičkog kretanja železničkog vozila