Cross-sectional Structure and Stress Distribution of National Standard Rails
- What parts does the cross-section of national-standard steel rails consist of? What are the functions of each part?
The cross-section of national-standard steel rails mainly includes the rail head, rail web and rail base. The rail head is in direct contact with the wheel and needs to bear the vertical pressure and friction of the wheel. Therefore, it is designed to be wide and thick to enhance wear resistance and pressure resistance. The rail web connects the rail head and the rail base, playing the role of transmitting force. Its thickness depends on the rail specification and can balance the stress of the rail head and rail base. The rail base has a large area, which can disperse the load to the sleeper, increase the contact area with the sleeper, reduce the pressure on the sleeper, and ensure the stable installation of the rail.
- What are the differences in rail head width among different specifications of national-standard steel rails?
The rail head width of 38kg/m steel rail is about 68mm, suitable for light-duty lines with small wheel pressure, so there is no need for an overly wide rail head. The rail head width of 43kg/m steel rail is about 70mm, slightly wider than that of 38kg/m steel rail, which can adapt to slightly larger loads. The rail head width of 50kg/m steel rail increases to 70mm, and the contact effect with the wheel is improved by optimizing the rail head profile. The rail head width of 60kg/m steel rail is about 73mm, and the wider rail head can disperse greater pressure, meeting the needs of trunk railways and heavy-haul transportation.
- What impact does the rail web thickness have on the stress of national-standard steel rails?
Rail web thickness directly affects the overall stiffness of the rail. The greater the thickness, the stronger the rail's ability to resist bending deformation. The rail web of 38kg/m steel rail is thinner, about 10.7mm, suitable for scenarios with small stress; the rail web thickness of 60kg/m steel rail reaches 16.5mm, which can bear greater bending moment and is not easy to bend when the train passes. If the rail web thickness is insufficient, the rail is prone to excessive deformation under load, affecting the smooth operation of the train; excessive thickness will increase the weight and cost of the rail.
- What is the function of the rail base slope design of national-standard steel rails?
The rail base slope is the slope formed by the contact surface between the rail base and the sleeper, usually 1:40. This design enables the wheel tread to better contact with the top surface of the rail head, allowing the load to be evenly distributed on both sides of the rail head, avoiding excessive uneven wear caused by excessive unilateral stress on the rail head. A reasonable rail base slope can also reduce the lateral force during train operation, reduce abnormal wear of rails and wheels, and improve the service life of the track and driving safety.
- What is the significance of the symmetry of the cross-sectional structure to the performance of national-standard steel rails?
A rail with a symmetrical cross-sectional structure can evenly transmit loads when stressed, avoiding torsional deformation due to uneven stress. The symmetrical design of the rail web and rail base can ensure the left-right balance of the rail during installation, reducing additional stress caused by installation deviations. If the cross-section is asymmetric, the rail will produce lateral bending under load, aggravating local wear of the rail head and rail web, and even affecting the running stability of the train. Therefore, symmetry is an important principle in the design of national-standard steel rails.