| With the rapid development of China’s rail transit,rail transport no longer only pursues speed and traffic volume,but also puts forward higher requirements for train safety and comfort.As an important part of the track structure,the track fastener plays the role of fixing the rail and bearing the load of the vehicle.It requires certain elasticity and insulation properties,and can control the lateral and longitudinal movement of the rail under vehicle operation and environmental loads.Its structure performance has an important impact on the stability,safety and comfort of the entire train.According to statistics,the number of passengers transported by the railway sector has been increasing year by year,with high-speed trains accounting for more than 80 percent of passenger transport.At the same time,the country attaches great importance to railway construction,in the 2019 national "two sessions" government work report,railway construction investment has remained above 800 billion.Therefore,it is very necessary to solve the problem of the failure of rail fasteners,no matter from the safe travel of the people or the national economy.This article aims at the common rail fasteners in China,and studies the factors that cause the fastener failure.The fastener clip fracture is the main factor that causes the failure of fasteners.Then,the failure of DI fastener clip is taken as the research object.A finite element model of rail fasteners is established.The mechanical performance analysis and frequency response dynamic analysis analyze the factors affecting the fracture of the fastener clip,and predict the fatigue life of the fastener clip.Finally,the structural optimization scheme of the fastener clip is proposed.To sum up,the main research contents are as follows:(1)Failure status of rail fastener.Count the commonly used rail fasteners in China,use the Failure tree analysis method to mine the failure factors of rail fastener failures and the logical relationship between them,draw the failure tree of rail fastener failures,and finally determine the weak links of rail fasteners.(2)Static performance analysis of fastener clip.Establish finite element model of rail fasteners,including bolts,fastener clips,iron backing plate,etc.and consider the static performance analysis of nonlinear contact of each contact component;focus on analyzingthe influence of the constraint length of the middle limbs of the fastener clip under different installation states and the toe load on the elastic range of the fastener clip and the maximum equivalent stress of the fastener clip.Quantify the stress distribution and the weak link of the fastener clip working state.(3)Modal analysis of fastener clip.Using the modal testing method of hammering and DASP software to perform modal testing on the free state and the assembled state of the fastener clip,and the natural frequency,the mode shape and other dynamic characteristics of the free state and the assembled state are analyzed in detail.At the same time,the dynamic characteristics of the trajectory system including the correlation between the sensitive characteristic frequency and the excitation frequency are analyzed and their effects.(4)Structural optimization and verification of fastener clip.Based on the principle of optimal design of fastener clip,a structure-optimized fastener clip-hollow fastener clip was proposed.The static performance analysis and the hollow fastener clip optimization index W verification were performed.Finally,the fatigue life of DI fastener clip and hollow fastener clip was predicted,and make a comparative analysis. |
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