Fatigue Reliability Ayalysis Of Freight Car Axle Under Random Loads

Axle is an important component for the safe running of rolling stock . With the development of heavy loading and raising speed of railway transportation, the fatigue reliability of the axle becomes a major problem in recent years in China. To ensure the safe running of rolling stock, it is essential to set a high goal for the detection and service life of the axle. So how to predict the fatigue life of the axle exactly has been paid much attention by scholars home and abroad.Load spectrum acted on the wheelset is obtained through dynamic simulation ,which is the key to the evaluation of fatigue reliability of the axle .In this paper, the type RD axle of the speed raised freight car is mainly studied. The nonlinear dynamic model of the type C62 and C64K freight car is set up and the influence of random irregularity of track is taken into consideration. The vehicle system dynamic responses are simulated in time domain ,through which the load time histories acted on the wheelset are acquired in different cases and the load spectrum are obtained by using the method of four-dimensional statistics.Using ANSYS finite element analysis software, the finite element model of the wheelset is set up . The stress spectrum of the axle whose material property is regarded as elastic-plastic cyclic nonlinear under different load cases are carried out using wheelset finite element model. Based on the axle stress spectrum of the serious sections , probabilistic fatigue stress spectrums with different reliability and confidence degree can be achieved ,which is fundamental for the prediction of the fatigue life and safe evaluation of the type RD axle.