Numerical Simulation Analysis Of Rail-Cracks Under Rolling Contact

The wheel/rail rolling contact arises some problems of the wheel/rail performance, such as wear abrasion by means of friction. The damage cumulate induce fatigue crack initiation and propagation, ultimately which can cause flaking and shelling on the local wheel/rail surface. Then the wheel/rail rolling contact on the rough surface, which could be accelerating the wheel/rail wear abrasion by means of friction. In the course of the wheel/rail rolling contact giving rise to sudden rupture of the wheel/rail is extraordinary serious accident. Therefore, to assure the safety of railway vehicles, it is necessary to investigate the problem about wheel/rail rolling contact fatigue.The rolling contact deal with the non-linear problem of physics, geometry and boundary condition, investigate the rolling contact fatigue crack is the most difficult and most complicated problem, most investigator study fracture mechanics characteristic of the crack defect in the range of linear-elastic. In this paper the distribution of elastic-plastic stress in the wheel/rail, and the fracture intensity J -integral of fatigue cracks in rail was calculated by using software MSC.Marc.Considering the real wheel/rail geometry and boundary condition, establish reasonable analysis model. Analyze the distribution of elastic-plastic stress and strain in the wheel/rail, the effect of the inclusion an crack in the rail surface on the distribution of elastic-plastic stress in railhead;the influence of the rail/wheel rolling contact with friction and the sleeper supporting on the different cracks was studied.Established crack analysis model for differ half-ellipse model surface crack in railhead. When the length of the cracks was unchangeable, the depth of the cracks was changeable, the conclusions show that the J -integral of the cracks tip increases while the wheel is close to the cracks, but it decreases while the wheel departs;the influence of wheel rolling on cracks decreases gradually with the increment of the depth of cracks. As the distance between the wheel and the crack is beyond 30mm, the wheel rolling has no influence on the crack. Whenthe length of cracks was changeable, and the depth of the cracks was also changeable, the conclusions show that as the size of cracks increases the J -integral of the crack tip increases little.In conclusion, half-ellipse model cracks propagate firstly to the depth direction in railhead;the semicircle model cracks are more stable than half-ellipse model cracks. When the crack situated over the sleeper supporting the J -integral value of the crack tip is bigger than it situated between two sleepers supporting, half-ellipse model cracks more easily propagate to the depth direction in railhead.