International Journal of Vehicle Structures and Systems

Sanjay Shukla ¹, Rajive Gupta ², Nalinaksh S. Vyas ³

Affiliations
1 Ministry of Railways, Government of India, Lucknow, IN
2 Harcourt Butler Technological Institute, Kanpur, IN
3 Indian Institute of Technology, Kanpur, IN

Abstract

Approximately three hundred thousand three-piece bogie freight vehicles presently operate under Indian Railways. The dynamic behavior of a vehicle depends on primary and secondary suspension elements. In the present work, a parametric study of suspension elements has been performed at various operating speeds to analyze the ride index of vehicle. The freight vehicle model considered in the present work comprises 70 degrees of freedom (DOF). Spring indices of various springs used as suspension elements and damping coefficients of wedge block as well as elastomeric pad have been obtained experimentally. These values have been used along with actual recorded track irregularities data to solve a vehicle model using ADAMS/Rail. The behavior of vertical acceleration and ride index of the vehicle for different speeds limits have been observed. The parameters of suspensions elements have been sequentially varied and their effects on vertical acceleration and ride index have been studied for vehicle speeds up to 110 kmph. A new set of parameters for suspension elements which gives improved ride index has been suggested on the basis of results obtained.

Keywords

Freight vehicle; Three piece bogie; Ride index; Vehicle dynamics; Suspension systems

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Sanjay Shukla ¹, Rajive Gupta ², Nalinaksh S. Vyas ³

Affiliations
1 Research Design and Standards Organization, Ministry of Railways, Lucknow, IN
2 Department of Mechanical Engineering, Harcourt Butler Technological Institute, Kanpur, IN
3 Department of Mechanical Engineering, Indian Institute of Technology, Kanpur, IN

Abstract

Weight and strength are critical measures in the design of a railway bogie. The present work deals with the design of CASNUB bogie bolster of freight rolling stock in Indian Railways. The bogie is modelled using NX3, UGS software. Finite element analysis of the model is performed using MSC Patran/Nastran. Natural frequencies obtained from free vibration analysis are compared with those obtained experimentally using a Rap-Test. Effort has been made to reduce the weight of bogie bolster considering fatigue strength. Bogie loading includes vertical forces, longitudinal emergency brake force and vertical as well as lateral track excitations. Transient analysis of bogie is performed to identify the critical areas and surfaces relevant for weight reduction. Thicknesses of the bolster top, bottom and side surfaces are subsequently identified as design variables. These parameters are optimized using artificial neural network and genetic algorithm techniques. Such optimization has resulted in approximately 7.6% reduction in weight of the bolster. The optimal bogie bolster has been verified for its fatigue strength using Goodman diagram.

Keywords

Bogie Frame, Finite Element Analysis, Weight Reduction, Fatigue Strength, Transient Analysis.

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Sachin S. Harak ¹, Satish C. Sharma ¹, Sanjay Shukla ², Parinay Gupta ², Sanjay Kumar ², S. P. Harsha ¹

Affiliations
1 Vibration and Noise Control Lab., Mech. and Ind. Engg. Dept., Indian Institute of Technology, Roorkee, IN
2 Research Design and Standards Organization, Ministry of Railways, Lucknow, IN

Abstract

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.

Keywords

Draft Gear, Draft Pad, Natural Frequency, Crack, Mode Shape, Finite Element Method.

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