Research On The Load Spectrum Of The Link Bar For Radial Bogies With Sub-Frames

Socio-economic development makes ever-increasing demands on the speed and volume of railway freight. In this situation, Chinese railway freight develops towards high speed and heavy haul. With the increase in traffic and axle load, wheel-rail wear also will be intensified.Therefore, reducing wheel-rail wear and to improve curve-passing performance of freight trains are problems to be solved. Utilizing radial bogie for heavy haul railway truck is an effective technical measure to reduce wheel and rail wear. In view of this, basing on the introduction of South Africa’s Scheffel Bogie on behalf of the mature bogie technology, China successfully developed the ZK7sub-framed self-steering radial bogie, which is applied in the Datong-Qinhuangdao railway line with small quantity.With the increase in the speed and the axle load of train, the overload situation of the structural member of rolling stock becomes worse, resulting in a larger dynamic deformation in certain parts of the structural member. In the long-term effects of the random stress, the load-bearing structure began to accumulate damage from the part with higher stress and strain.When the damage reaches a certain level, it will lead to fatigue failure, seriously endangering running safety of rolling stock. The fatigue reliability issues of sub-frame structure as core component of the ZK7bogie should be highly concerned. In addition to the axle box load, the sub-frame structure will withstand the horizontal-plane interaction passed by the link bars between the front and rear wheelset. The load spectrum of the link bar is important input data for fatigue design and strength analysis of the sub-frame structure. The preparation of the load spectrum is a prerequisite for fatigue tests, fatigue life estimation and fatigue strength assessment.In this paper, dynamics model of CsoBF type gondola equipped with the ZK7type bogie was established in the multi-body dynamics software SIMPACK. Then, we had a dynamic performance analysis on the wagon model to verify that the dynamics performance indicators of the wagon model in line with vehicle system dynamics standard according to GB/T5599-1985.On the base of the wagon model, the load spectrum of the link bar of ZK7bogie was prepared by the method of numerical simulation, according to the features of the Datong-Qinhuangdao railway line. At last, we had an Analysis of the effect of curve radius, off-Balance Super elevation and axle load on mean load and load amplitude of the link bar.The result is as follows. From the load spectrum of the link bar for round-trip, we can find that the maximum mean load is about18kN, which is equal to the maximum mean load of the load spectrum of the link bar for, one-way in condition of loaded wagon. The maximum load amplitude of the load spectrum for round-trip is about45kN, which is equal to the maximum load of the load spectrum for, one-way in condition of loaded wagon. The number of load cycles is up to the maximum in the vicinity of the zero-mean and amplitude range up to3kN to6kN.As the load mean value and the amplitude increases, the number of load cycles substantially reduced. In the analysis of various parameters on the mean load and load amplitude of the link bar, it indicates that the mean load and the load amplitude decrease with the increase of the radius of the curve. Within small radius of the curve, the mean load of the link bar in loaded wagon condition decreases rapidly with the increase of the radius of the curve. The mean load and the load amplitude increase with the increase of off-Balance Super elevation. Compared to results in empty car situation mean load and load amplitude of link bar increased considerably. The mean load increases slowly with the increase in axle load and the load amplitude increases with the increase in axle load.