Rail defects due to rolling contact fatigue

Abstract

Dynamic load on modern railways is increasing with speed, traffic and axle load. Defects due to rolling contact fatigue are becoming more expressed because of high wheel/rail contact stress. Rail grinding removes the material in expected or distinguished fatigue area and re-profiles rail cross section geometry. Re-profiled rail geometry is not unique; it depends heavily on the maintenance strategy. However, the objective of all rail grinding is unique: the intention to defer and delay rail defect recurrence. Such maintenance strategy requires the repetition of grinding activities, which are part of 'railcare'. Serbian Railways still don't have a developed railway superstructure maintenance strategy which includes rail-care activities. This paper presents the experience of railway managements in Europe and gives an overview and analysis of research results in the area of rail defects due to rolling contact fatigue (head checking, squat, belgrospi).

Sa porastom brzina, osovinskog i saobraćajnog opterećenja na savremenim železničkim prugama raste dinamičko opterećenje. Zbog velikih kontaktnih napona u dodiru točka i šine, pojava defekata šine usled zamora materijala postaje sve izraženija. Brušenjem šina uklanja se materijal u očekivanoj, ili uočenoj zoni zamora čelika i vrši reprofilisanje geometrije poprečnog preseka šine. Oblik geometrije reprofilisane šine nije jedinstven, već izrazito zavisi od strategije održavanja. Ipak, cilj svih strategija brušenja je jedinstven. To je namera da se odloži i uspori ponovna pojava defekta šine u koloseku. Ovakva strategija održavanja zahteva ponavljanje aktivnosti brušenja, koje spadaju u 'negu šine'. Na Železnicama Srbije još uvek ne postoji razvijena strategija održavanja gornjeg stroja železničkih pruga koja uključuje aktivnosti nege šine u koloseku. U ovom radu se iznose iskustva železničkih uprava u Evropi i daje pregled i analiza rezultata istraživanja iz oblasti šinskih defekata usled zamora materijala (head checking, squat, belgrospi).