Data Processing for the Life Assessment of Wheel Centers of Electric Locomotives.

During the factory repairs of electric locomotives of all series and indices VL8, VL10, VL60, VL40, VL80, and VL82M (hereinafter referred to as VLv/i series electric locomotives) in the mid-20s, an unforeseen increase in the number of cast wheel centers with cracks was noted simultaneously at different domestic plants. The maximum number of axles of wheelsets withdrawn from service for various reasons was observed during 16–20 years of operation. At the same time, the duration of operation of a larger total number of wheel centers was more than 30 years. Cases of cracking in cast hub centers and spokes have been reported. There is a need for 100% control of hub cracks in the wheel centers of electric locomotives of the VLv/i series. The most common cause of failure of cast wheel centers in operation is their increased susceptibility to cracking due to casting defects. Increasing the service reliability of wheel centers is achieved by using rolled centers in locomotives, which have higher material quality and a homogeneous structure. Currently, no requirements are imposed on locomotive wheelsets in terms of the limiting value of the probability of cracking in wheel center hubs, which makes it impossible to predict their service life. So far, the peculiarities of fatigue cracks in the hubs of cast and rolled locomotive wheel centers operating under giga-cycle loading have not been sufficiently studied. An urgent task is to process statistical data on the establishment of wheelset mileages, particularly for the electric locomotives of the VLv/i series, with a given probability of the appearance of fatigue cracks. We assumed that the probability of safe mileage of wheel centers should be 0.001% with an acceptable probability of operation of the entire wheelset of 0.991. The given probability of safe operation of the wheelset centers of electric locomotives makes it possible to carry out a statistical analysis of the probability distribution of the mileage of the repaired wheel centers of each series of electric locomotives. The cumulative probability of failure-free operation of wheel centers is estimated using the central theorem, according to which the distribution function of the sum of a large number of independent random variables with a finite value of mathematical expectation and variance is reduced to the function of the normal probability distribution of the occurrence of unrepairable wheel centers of electric locomotives of this series. The analysis of the normal distribution of fatigue life under the giga-cycle loading of each series's wheel centers of electric locomotives allows one to determine the identity of their reliability. The problem of avoiding the unstable operation of locomotive repair plants without detecting out-of-service wheelset centers has been solved. [ABSTRACT FROM AUTHOR]