| Reliability analysis has been being an important research topic in the field of modern engineering, which has become a trend in modern design. High-speed and heavy-duty have made the damage of wheel tread and the rail surface more serious, friction heat is to be the main cause leading to material damage of wheel and rail, so the analyzing their impact on the strength reliability of wheel-rail structure will have an important practical significance. All previous studies on wheel-rail had been embarking on the level of stress and had analyzed the influence of some related parameters on the stress and security of wheel-rail structure, but all of these had not come to get the specific data of the affecting size, which means having no specific data supports to the research of strength and security of wheel-rail.In this paper,rail as research object, based on the Monte Carlo method of probabilistic finite element, the ANSYS command programs APDL had been applied to establish the parametric model of wheel-rail in the sliding friction contact conditions, the ANSYS PDS module had been used to conduct the reliability analysis of rail contact surface. So this paper had specifically analyzed the impact of input random variables of material parameters, axle load and sliding velocity on rail contact surface reliability under the conditions of mechanical and thermal-mechanical coupled load. Calculations had taken the uncertainty of the input random variables into account and had received reliability counting results of response parameters (temperature,stress etc) of rail structure. Meanwhile, its sensitivity analysis, relationship analysis and inverse probability analysis had been executed, and we had obtained sample history curves, histograms and scatter plots of rail response variables, and the results of reliability were compared with the results of stress analysis. The results showed that:1) The relative sliding of wheel-rail produced a significant frictional heating effect, the heating zone focused on the contact area. Because the relative sliding of contact area led to bring instantaneous temperature rise and resulted in generating the thermal stress which has the same magnitude order to mechanical stress in contact area.The stress states of material were greatly deteriorated and the destructions of material were also largely exacerbated when high stress concentrations were appeared.2) Under mechanical load conditions,rail contact surface have undergone plastic deformation, but the structure was still in a safe state, which is considered that the rail contact surface is safe and reliable on this condition.Because,using reliability analysis to the rail contact surface:At the confidence level of0.95,the probability that the equivalent stress is greater than the yield limit of rail contact surface is l,and the probability also is1that he equivalent stress is less than its ultimate strength,which means the reliability of rail contact surface is1; At the same time,the probability is1that state equation ZT of ultimate strength is less than0,and the probability also is1that the state equation ZY of yield limit is greater than0, which means the reliability also is1.3) In the sliding friction heating coupling load conditions,the great probability that the rail material plastic deformation occurred in contact area is0.98,and the probability of failure is0.94that means great,which indicated the rail contact surface is not reliable on this condition.By the frictional thermal reliability analysis of rail contact surface discovering that:At the confidence level of0.95,the probability that equivalent stress of rail contact surface is greater than yield limit is0.98,and the probability that equivalent stress is less than the ultimate strength is0.05,which means the reliability is0.05;What is more,the probability is0.06when the state equation ST of ultimate strength is less than0,and the probability is0.98when the state equation SY of yield limit is greater than0,which implies the reliability of rail structure is0.06. |
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