The Fatigue Life Analysis Of High-speed Railway Contact System

Electric railway has advanced towards the trend of high-speed, it is highly important to analysis the fatigue life for the safety of catenary system. In this thesis, the main task is to analysis the fatigue life for the safety of catenary system, study unfavourable positions of the fatigue life and Pantograph-Catenary parameters on the contact line of life.Described a method of estimating fatigue life based on the principles of finite life design method. The paper uses the APDL programming language to estimate fatigue life of the flexible suspension catenary system. The innovation point is the method of gaining the fatigue load spectrum. This paper gives two methods to estimate fatigue life of the flexible suspension catenary system: simplified load spectrum method and rain-flow counting method, and compares their differences of fatigue life.Through the simplified load spectrum method, stress-time curve of contact wire elements is simplified as a maximum stress cycle, after the correction of Goodman straight-line, the fatigue life of each element on contact wire is gained directly through the S-N curves. Rain-flow counting method is an emphasis of this thesis. Improved rain-flow counting method is adopted to gain different stress amplitudes, stress averages and their corresponding stress cycles from the fatigue stress spectrum of each element on contact wire. According to Goodman straight-line, the rain-flow counting results are converted to stress cycles with null means, then through the S-N curves, the paper gains the cycle number of elements when fractured in different stress amplitudes. Based on Miner linear cumulative damage theory of fatigue, the fatigue life of contact wire elements is estimated. In theory, the simplified load spectrum method ignores other stress cycles except the maximum stress cycle, so the fatigue life is higher.The thesis analyses unfavourable positions of the fatigue life and their stress-time curves, calculates fatigue life of each element on contact wire through two methods respectively, analyses the position which the difference of two methods is greater than 40% on contact wire, in those position, rain-flow counting method is more precise to estimate fatigue life of contact wire. Besides, in the same parameters, the thesis analysis the factors affecting the fatigue life, including span, the force of contact line and messenger wire, section areas, the train speed, the constant force, dry friction, and so on. Compare the contact life based on the simple chain and elastic chain hanging, found out several key factors that affect current collection of catenary by comparing each group parameters. The conclusion of this paper provides the important basis for the design, construction and maintenance of the flexible catenary system.