The Reliability And Safety Analysis Software System For Railway Vehicle Axles

Axle is one of the important parts of railway vehicles dealing transportation safety. It is established of a software system for assessing the fatigue reliability and safety of railway axles. Five functions can be realized by this system. One is to get semi-automatic parametric drawing of the axles. Second is to calculate the fatigue stress spectrum of the axles by the criterion [TB/T239-1996, the Design of Railway Vehicle and the Mothod of Intensity Caculation]. Third is to predict the fatigue life with a given reliability level and to evaluate the reliability under a given service life. The fourth is to predict the residual fatigue crack growth life when the axles with a initial crack size and measure the critical safety crack size to assure the axle's safety before the coming entirely inspection. And the fifth is to get the entire analysis results in a file of TXT format and to drawing the axle in an AutoCAD environment. In which, the parametric drawing is made by defining the data structure of the axles and introducing the general algorithm on a basis of the principles of feature modeling. The stress spectrum at a given section of the axle is evaluated through the given load time history of wheel-set gotten by establishing the equilibrium model of forces of the wheel-set, vehicle and bogie system. The reliability life prediction and safety assessment are made by the stress-time history in the most dangerous section of the axle, which the section is determined by comparing the equivalent stresses of the stress spectrum in the various sections of the axle. In the prediction and assessment process, the random cyclic constitutive relations are taken into account and a new crack growth rate model is applied where the threshold â–³K_th and the fracture roughness K\c are incorporated. In addition, both the survival probability and confidence are considered in the present reliability analysis and safety assessment. The availability of the system is indicated by a reliability analysis and a safety assessment of the RD_3A type axle with the inspected loading spectrum on Jing-Qing railway line.