Fatigue Stress Analysis Of The Key Components Of C70 Type Railway Freight Car

Fatigue loads and stress spetrum are investigated into the the key components including wheelset, boster, and side frames of China C70 type freight car. This car having 23t axle weight was put into production in 2005 for replacing the elder 21t axle weight one. It is now the main type of rolling stock in China cargo transporation, which has been running in whole railway line network of China.For the complex service environment of China whole railway line network, the service loads for fatigue analysis are seldom enough only by line inspection or dynamics simulation. To obtain a liable fatigue prediction, an integrated method is practiced on a basis of understanding on the elements for making up the whole line network structure in terms of line sampling and grading. The loads in each element are liably determined by combining a line inspection and a dynamics simulation. The fatigue load spectrum for the key components is finally determined by summing up the loads of whole elements.An efficient finite element (FE) method, multivariate quadratic regression approach, is proposed for calculating the fatigue stress spectrum of engineering structures, to overcoming the defficies of much time cost in transient approach and the inadequate assumption of material entire linear-elasticity state in quasi-static approach. The calculation starts from a dynamic load history. A regression function is established as a relation from the concurrent components of structural balance force systems into the structural stress. Parameters of the relation are measured by the stress data using an elastic-plastic FE method under selected groups of balance force systems. The selected systems should cover the possible load range with a similar service condition. After passing the fit effect check, the regression equation can transfer the structural load history into the stress history at the preferred position. Application on the determination of fatigue stress spectrum for the key component s of C70 type freight car has indicated availability of the present approach.Present work provides a basis of reliability analysis for the key components of C70 freight car. It can be also applied for the fatigue loads and stress analysis of other railway vehicles.