Design Reliability Analysis On The Wheel-Axle Of Railway Freight Car With27Tons Axle Weight

Design reliability analysis is performed on the wheelset of railway freight car with27t axle weight. An integrated finite element method formerly presented by supervisor’s research team is applied to construct the calculation model of key location stresses for the wheelset. Loading set are carried out including the conditions matching the codes of AAR-S660and EN13979, and the wheel-truck contact force-time sequence from on-line inspection. Mechanical and fatigue stresses are then determined on the tread, web, and gub of HEZE915type wheel, and the sections of inner-outer wheel seat and axle neck root of RE2C type axle. Mechanical strength assessement is made by the material probabilistic mechanical properties matching the regularities of code AAR-S660. Fatigue strength assessement is carried out by the probabilistic fatigue limits in accordance with code EN13979. And fatigue reliability analysis is made by the probabilistic fatigue S-N curves including super long life regime for the wheel-truck contact force-time sequence.One of most contributions of this thesis is that wheel-truck contact fatigue reliability analysis is carried out using a statistical shear stress spectrum acting on the wheel tread from the wheel-truck contact force-time sequence. It is revealed that the fatigue crack is most probably initiated from the inner layer around2mm below the tread surface. In addition, Same damage level is found at the inner layer around3.4mm below the tread. This indicates why the invisible cracking phenomena were frequently appeared in production, and provides guidance how to monitoring wheel tread fatigue damage and treating the tread maintenance.Another contribution of this thesis is that fatigue reliability analysis is made to the subsurface locations of the axle wheel seat using a statistical shear stress spectrum due to the wheel-truck contact force-time sequence. It revealed that fatigue cracks are probably initiated from the location29.7mm below the surface and24.1mm away from inner side surface of the fitted wheel. This indcated that the wheel seat inner cracking check is an important task to assure the axle safety in service.