Thermal analysis of railway axle box to predict the axle overheat

초록

If the axle bearing of the railway bogie is damaged or the grease freezes, the excessive friction between the axle and bearing may overheat the axle. This situation may induce the derailment of the train. To ensure the structural safety of the axle in real time, it is necessary to locally monitor the axle box with temperature sensors. To predict the axle temperature from the axle box temperature, a computational model of the axle box was generated for the heat transfer analysis in the present paper. At the beginning of the modeling, we removed the detailed surfaces and simplified the geometry of the axle box system in preparation of generating the elements. Finite element model consists of an axle cover, axle bearings, an axle and the air gap between the axle and the front cover of the axle box. On the reference plane, the lines shared with node points were extracted. The axle box was constituted with tetrahedral elements owing to the complicated curved surface. The others were constituted with solid elements. The generated elements shared the equivalent nodes. For realistic modeling of the part, solid type elements such as solid 70 (3-D Thermal Solid) were used. Nodes of each part were shared for the heat transfer. The whole system has 211,398 nodes and 205,482 elements. Elements were meshed by hexahedron mesh which has eight nodes. The specific heat and the thermal conductivity were applied to ANSYS for the thermal analysis following the temperature condition of the material. The temperature distribution of the axle box was analyzed when the temperature of the axle was stabilized and became constant. The temperature difference between the front cover of the axle box and axle was 20℃ approximately.