Analysis of Failure of Hanger Pins in Pakistan Railways Carriages

Abstract

The frequency of failures in hanger pins of Pakistan Railway carriages has risen to an alarming level. Such as hanger pins have become the reason for the highest number of cases regarding failures of Carriage and Wagons in Pakistan. The pins have been failing after only 3 months while the intended life of these pins was supposed to be 6 months at least. These fatigue stresses must be controlled to an acceptable level through an efficient process in order to prevent failures in carriages. Previously we have been using rectangular cross-section cotter pins in the hanger brackets. Studies have shown that instead a circular cross-section cotter pin can make a major contribution to the lower the value of these fatigue stresses. There have been no studies on this particular project due to which it is the first of its kind in Pakistan Railways. In this study, we compute and perform the stress analysis as well as the fatigue analysis on the hanger pin assembly using the Findley criterion procedure in-order to become more real to the problem. The Findley criterion was used as it most closely resembled in the properties needed to carry out our desired simulation. We employ a three-dimensional COMSOL model to compute the stresses as well as do the fatigue analysis on the said model. Fatigue usage factor has been used in the COMSOL. The first part contains the analysis on the already in-effect hanger pins of rectangular cross-sectional area. While the second half contains analysis done by changing the cross-section to modified circular shaped hanger cotter pins. Permission to perform the said analysis and used the facilities in hand was taken from Divisional Mechanical Engineer. If the project is a success it will be a major cause for reduction in the number of cases regarding derailment in Pakistan Railways as a whole.