Weight Reduction in an Indian Railway CASNUB Bogie Bolster Considering Fatigue Strength

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.