The Research Of Rail Damage Behavior

Rail as an important part of railway transportation, the quality of rail should be improved with the rapid development of high-speed and heavy rail. The damage forms of rail mainly include fatigue, abrasion and stripping. If the rail damage is not maintained in a timely manner, it will influence the safety of the train even can also cause rail fracture. Therefore, the study of the crack on the rail surface can understand the mechanism of rail damage clearly. This can also reduce not only the operating cost but also the risk of operation.The finite element software ANSYS was used to study the fatigue problems of rail with surface crack in this thesis. Firstly, the maximum circumferential stress criterion was introduced and the maximum circumferential stress criterion was proved to be useful in the analysis of the crack propagation path. The maximum circumferential stress criterion and the equivalent stress intensity factor fracture criterion was used to analyze the extending behavior of crack under the wheel-rail contact. The main propagation path of crack was analyzed by considering the secondary crack. It was analyzed that the crack propagation path of multiple crack under the different spacing. The competition of rail fatigue and abrasion was analyzed as well. The following conclusions were obtained:1.The maximum circumferential stress criterion can not truly simulate the oblique crack extension path when it was used to analyze the micro crack extending behavior under the wheel-rail contact, but the equivalent stress intensity factor fracture criterion could more truly simulate the oblique crack extension path.2.The inclined crack propagation rate reached the maximum when the crack extension angle changed from acute to obtuse.3.The stress concentration at crack tip would be released after considering the secondary crack and the equivalent stress intensity factor would also decrease. The main crack propagation direction and the secondary crack propagation direction were basically remain unchanged after considering secondary crack.4.There would be many split cracks when the second crack extension no matter the space was 0.5 mm or 1 mm between the cracks. And the second crack would eventually intersect with the first crack. This led to the formation of the rail surface stripping. And the size of the crack spacing would affect the rate of crack propagation significantly.5.Crack propagation rate was significantly greater than the wear rate of crack no matter single crack or multiple crack. Rail failure modes was given priority to contact fatigue.