The Study On Fatigue Reliability Of The Aluminum Beam Of High Speed Train Carbody

With the rapid development of the High-Speed Railway in China, higher requirements were put forward for the reliability and safety during the operation because of its high speed. So the fatigue reliability of the the aluminum beam, which was a hanging structure for the equipments under the vehicle, is a fatal factor which can guarantees to the trains safe operation. For this, three different homemade aluminum beam of the High-Speed train body were taken as research object, and the main content of this paper is as following:1. Fatigue test on three different full size aluminum beam samples was conducted, with the single-point method and the group method. The load-life curves in different possibility were obtained;2. The load and constraints of the Aluminum beam specimens were simulated and load calculation was analyzed by Finite element method so that the connection between load and maximum stress of the beam was obtained as well as the load-stress transfer coefficient, which can be used for drawing the P-S-N curves with the load-life curves. According to the ECCS and BSK standard, the P-S-N curves were extrapolated;3. The dynamic load of the force bolts was acquired, and the eight grate load spectrum of the force bolts was complied. The eight grate stress spectrum of the aluminum beam also acquired by using the load-stress transfer coefficient; This eight grate stress spectrum was amend by goodman curves equation for the reason of the effect of the average stress;4. The maximum value of stress was inferred by the distribution fitting and hypothesis testing of the the measured stress spectrum, which was obtained by using method of mathematical statistics, and the statistic stress spectrum was also complied.5. The aluminum beam’s fatigue life was predicted based the measured stress spectrum and the statistic spectrum by using the Corten-Dolan nonlinear cumulative damage theory and Miner linear cumulative damage theory respectively.The research results show that:The fatigue property of B type aluminum beam was worst compared to the others, but, the predicted fatigue life of three types of aluminum beam could meet the requirements of12000km which was a design operation mileage. The predicted fatigue life which was based on the probability distribution of the stress amplitude was shorter than that which was based on the measured stress spectrum; The calculated fatigue life was predicted by using the Corten-Dolann nonlinear cumulative damage theory was more conservative than that which was calculated by Miner linear cumulative damage theory. The research results of this paper can provide a technical and fatigue data support for the design and application of the homemade aluminum beam of High-Speed train.Some research methods in this paper also can be used in the research of the similar type problems.