92 research outputs found
Relation between reliability and availability of railway vehicles
Pouzdanost i raspoloživost železniÄkih vozila su znaÄajne karakteristike zbog Äega je vrlo važno utvrÄivanje i njihovog meÄusobnog odnosa. U radu je dat prikaz moguÄnosti odreÄivanja uticaja pouzdanosti železniÄkog vozila na njegovu raspoloživost na primeru koji uzima u obzir realne vrednosti tih karakteristika za uslove "Železnica Srbije". PotvrÄen je veliki znaÄaj ostvarenja visoke pouzdanosti voznih sredstava u uslovima njihovog održavanja sa malom efikasnoÅ”Äu. To, sa svoje strane, upuÄuje na obavezu "Železnica Srbije" da, pored stalnog podizanja nivoa efikasnosti održavanja prilikom modernizacije postojeÄih 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 izvrÅ”ena analiza uticaja matematiÄkog oÄekivanja i standardnog kvadratnog odstupanja trajne dinamiÄke ÄvrstoÄe materijala (kao kritiÄnog napona) na pouzdanost monoblok toÄka železniÄkog vozila pod dejstvom mehaniÄkih optereÄenja. Za proraÄun pouzdanosti koriÅ”Äena je metodologija koja podrazumeva odreÄivanje idealnih radnih napona u kritiÄnoj oblasti toÄka na osnovu raspodela optereÄenja dobijenih u eksploataciji i izraÄunavanje pouzdanosti na osnovu definisanih raspodela radnih i kritiÄnih 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 izvrÅ”ena analiza uticaja matematiÄkog oÄekivanja i standardnog kvadratnog odstupanja trajne dinamiÄke ÄvrstoÄe materijala (kao kritiÄnog napona) na pouzdanost monoblok toÄka železniÄkog vozila pod dejstvom mehaniÄkih optereÄenja. Za proraÄun pouzdanosti koriÅ”Äena je metodologija koja podrazumeva odreÄivanje idealnih radnih napona u kritiÄnoj oblasti toÄka na osnovu raspodela optereÄenja dobijenih u eksploataciji i izraÄunavanje pouzdanosti na osnovu definisanih raspodela radnih i kritiÄnih 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 železniÄkih vozila su znaÄajne karakteristike zbog Äega je vrlo važno utvrÄivanje i njihovog meÄusobnog odnosa. U radu je dat prikaz moguÄnosti odreÄivanja uticaja pouzdanosti železniÄkog vozila na njegovu raspoloživost na primeru koji uzima u obzir realne vrednosti tih karakteristika za uslove "Železnica Srbije". PotvrÄen je veliki znaÄaj ostvarenja visoke pouzdanosti voznih sredstava u uslovima njihovog održavanja sa malom efikasnoÅ”Äu. To, sa svoje strane, upuÄuje na obavezu "Železnica Srbije" da, pored stalnog podizanja nivoa efikasnosti održavanja prilikom modernizacije postojeÄih 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
TermiÄko optereÄenje monoblok toÄka železniÄkog vozila koÄenog papuÄama je dominantno u odnosu na ostale vrste optereÄenja. To optereÄenje, koje je uglavnom posledica dugotrajnog koÄenja na padovima u cilju održavanja brzine je osnovni uzrok pojave pukotina na povrÅ”ini kotrljanja toÄka i, kao krajnja posledica, loma toÄka. U radu su dati rezultati proraÄunske analize termiÄkog optereÄenja monoblok toÄka na odabranoj karakteristiÄnoj deonici pruge Jugoslovenskih železnica. ProraÄuni temperaturnih i naponskih stanja toÄka raÄeni su pomoÄu metode konaÄnih 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 proraÄun i eksperimentalna analiza naponskog stanja noseÄe strukture vagona za prevoz automobila. ProraÄunom je obuhvaÄena statiÄka i dinamiÄka analiza noseÄe strukture, kao i odreÄivanje torzione krutosti primenom metode konaÄnih elemenata. Analiza ÄvrstoÄe noseÄe strukture je obuhvatila i optereÄenje pod dejstvom boÄne sile nastale usled ubrzanja od 0,1 g. Analizirana je Äetvrtina vagona sa boÄnim vratima, kao najslabiji deo strukture. Ispitivanjem je obuhvaÄena noseÄa struktura vagona koja se sastoji od postolja, boÄnih stranica i dve pokretne platforme, bez Äeonih i boÄnih vrata kao i krova. Naponi su mereni pomoÄu mernih traka na 120 mernih mesta, od kojih su pojedina omoguÄavala merenje napona u sva tri pravca. Rezultati merenja pokazuju da su naponi u svim sluÄajevima optereÄenja znaÄajno ispod dozvoljenih. Zaostali naponi su bili u dozvoljenim granicama. Ugibi noseÄe strukture su bili veoma mali i nisu preÅ”li 0,6 ā° rastojanja osa svornjaka, Å”to je znaÄajno 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 0,6ā° from the centre pin distance, which is well below allowable value
Experimental verification of auto carrier car strength calculation
U radu je dat proraÄun i eksperimentalna analiza naponskog stanja noseÄe strukture vagona za prevoz automobila. ProraÄunom je obuhvaÄena statiÄka i dinamiÄka analiza noseÄe strukture, kao i odreÄivanje torzione krutosti primenom metode konaÄnih elemenata. Analiza ÄvrstoÄe noseÄe strukture je obuhvatila i optereÄenje pod dejstvom boÄne sile nastale usled ubrzanja od 0,1 g. Analizirana je Äetvrtina vagona sa boÄnim vratima, kao najslabiji deo strukture. Ispitivanjem je obuhvaÄena noseÄa struktura vagona koja se sastoji od postolja, boÄnih stranica i dve pokretne platforme, bez Äeonih i boÄnih vrata kao i krova. Naponi su mereni pomoÄu mernih traka na 120 mernih mesta, od kojih su pojedina omoguÄavala merenje napona u sva tri pravca. Rezultati merenja pokazuju da su naponi u svim sluÄajevima optereÄenja znaÄajno ispod dozvoljenih. Zaostali naponi su bili u dozvoljenim granicama. Ugibi noseÄe strukture su bili veoma mali i nisu preÅ”li 0,6 ā° rastojanja osa svornjaka, Å”to je znaÄajno 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 0,6ā° 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
TermiÄko optereÄenje monoblok toÄka železniÄkog vozila koÄenog papuÄama je dominantno u odnosu na ostale vrste optereÄenja. To optereÄenje, koje je uglavnom posledica dugotrajnog koÄenja na padovima u cilju održavanja brzine je osnovni uzrok pojave pukotina na povrÅ”ini kotrljanja toÄka i, kao krajnja posledica, loma toÄka. U radu su dati rezultati proraÄunske analize termiÄkog optereÄenja monoblok toÄka na odabranoj karakteristiÄnoj deonici pruge Jugoslovenskih železnica. ProraÄuni temperaturnih i naponskih stanja toÄka raÄeni su pomoÄu metode konaÄnih 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 zaÅ”tite putniÄkih vagona. Uloga pasivne zaÅ”tite je da posledice sudara svede na najmanju moguÄu meru. Apsorber razvijan u ovom radu sastoji se od ÄeliÄnih beÅ”avnih cevi u kvalitetu P235T1 i konusne Äaure napravljene od Äelika za poboljÅ”anje u kvalitetu C45E. Tokom sudara provlaÄenjem cevi kroz konusnu Äauru dolazi do redukcije - smanjenja preÄnika cevi pri Äemu se troÅ”i energija. U radu su analizirani rezultati dobijeni numeriÄkim simulacijama i dinamiÄkim ispitivanjima cevnih apsorbera kinetiÄke energije sudara putniÄkih vagona. Glavni cilj rada je uspostavljanje korelacije rezultata dobijenih numeriÄkim simulacijama i eksperimentalnim istraživanjima. KoriÅ”Äenjem karakteristiÄnih parametara dobijenih tokom kvazi-statiÄkih, dinamiÄkih ispitivanja i numeriÄkih simulacija, definisane su vrednosti kljuÄnih parametara koje se mogu koristiti za buduÄa ispitivanja cevnih apsorbera ovog tipa pri brzinama veÄim od 20 km/h. NumeriÄke simulacije se mogu koristiti u fazi razvoja apsorpcionih elemenata dok je za konaÄnu ocenu prototipa neophodno uraditi dinamiÄka 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 železniÄkog vozila sa trodelnim obrtnim postoljem
Za analizu kvazistatiÄkog i dinamiÄkog ponaÅ”anja železniÄkih danas se sve viÅ”e upotrebljavaju razliÄiti matematiÄki-numeriÄki modeli. Jedno od osnovnih pitanja koje se postavlja prilikom modeliranja mehaniÄkih sistema je u kojoj meri razvijeni model može taÄno opisati realni sistem. U ovom radu je prikazan model železniÄkog vozila za prevoz rude gvožÄa sa poveÄanom osovinskom nosivoÅ”Äu i izvrÅ”ena je validacija modela saglasno preporukama UIC-a. Za ocenu saglasnosti modela i realnog sistema poreÄena su ubrzanja u vertikalnoj i horizontalnoj ravni, vertikalne i boÄne sile u kontaktu toÄak Å”ina, za prazno i natovareno vozilo koje se kreÄe na pravcu i u krivini. Dobijeni rezultati pokazuju veliku saglasnost rezultata dobijenim eksperimentalnim ispitivanjem i simulacijom dinamiÄkog kretanja železniÄkog vozila
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