Finite Element Analysis On Performance Of Thermite Welding Joint In Continuous Welded Rail

Continuous welded rail is an important symbol of the development and progress of railway. It also promotes the improvement of social productivity. Continuous welded rail, which is based on rail welding technology, takes the place of most common rail joint with rail welding. It not only saves a lot of rail joint materials but also meets the requirements of train’s high-speed operation. With the development of high-speed and heavy-load continuous welded rail, quality and stability problem of rail welding joint is increasingly aggravating. What’s more, thermite welding joint which is the vulnerable link of continuous welded rail will harm the safety under critical condition. Therefore, doing research of the performance and stability of rail thermite welding appears significant.Aiming at studying the performance of welding joint, feasibility of Finite Element Analysis (FEA) of welding joint was analyzed combined with parameters of thermite welding. Based on the thermal analysis theory of rail thermite welding, the heat transfer model of rail thermite welding was constructed, which contained thermal conduction, convection and radiation. Computational fluid dynamics software was used to do the finite element analysis of rail thermite welding process with the side top gating system which had dual risers. The welding parameters of rail thermite welding under different thermal conditions were figured out, which provided the basis for construction of finite element model of rail themite welding joint under wheel-rail rolling contact state.The normal force distribution under wheel-rail contact was acquired using Hertz Contact Theory, and the wheel-rail contact relationship was calculated based on the vehicle-track coupling kinetic model. And also joints’ dynamics with irregularity of shortwave and low collapse of welding joint was considered. The results indicate that the normal force of wheel-rail impact load is increasing linearly as the vehicle speed increases and decreasing as the distance between welding joint and the nearer sleeper increases and so on. Finite element model of welding joint of wheel-rail contact was constructed, and the mechanical performance of joint was analyzed under wheel-rail rolling and sliding conditions combined with different impact parameters. The results show that trains’emergency braking and wheel idling of start and acceleration should be avoided. The welds should be set as far as possible to the adjacent sleeper. At the same time, we need to develop thermite welding process continuously, and improve the performance of welded joints, and reduce welding defects in order to decrease or even avoid the irregularity of shortwave and low collapse of welding joint caused by repeatedly wheel-rail contact.The theme of the paper was summarized, and the research conclusion are analyzed and summed up. The advantage of integrated study of welding process simulation and welded joint finite element analysis was demonstrated. The results have certain reference value for the application of practical engineering. At last, the limitations of the paper are expounded and follow-up researches are prospected.