Effect of Multiple Location Defects on the Dynamics of Draft Gear used in Freight Railway Wagon

The present work investigates the effect of crack location on the modal frequency of draft gear used in autocouplers of freight railway wagon for various orientations. First seven mode shapes of a healthy draft gear have been determined using finite element approach. Defect of semi-elliptical shape is modelled in the lateral as well as longitudinal direction of the draft pad which is a component of draft gear. Various damage scenarios have been simulated by considering multiple locations of the crack in the draft gear for different orientations. Effect of crack orientation and defective pads location on the natural frequency of draft gear is analysed. It is seen that for single defective pad as well as multiple defective pads, the natural frequency of draft gear is dependent on the dynamics of draft pad. It is also observed that defect in consecutive pads causes more change in frequency as compared to single defective pad. As far as the location of defective pad is concerned, it is seen that the draft gear frequency is more sensitive to defective pads located either near the housing base plate or top follower. This study provides a tool to diagnose crack defect in draft gear based on vibration characteristics.