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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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1. Introduction
A freight vehicle bogie consists of bolster, side frame, wheel set and car body. Bogie frame is a crucial structural assembly subjected to various static and dynamic forces from car body and wheel sets respectively. The motion of the railway vehicle is dependent on geometry of the track and wheel set, interaction between wheels and rails and the suspension parameters. The weight of the bogie should be kept less for high operating speeds. In order to obtain an optimum design, a process of iterative evaluation and geometrical modification of parts is required. The strength of the bogie is normally calculated according to International standards such as UIC [1] and ERRI [2]. CASNUB three-piece freight bogie, as shown in Fig. 1, is considered in this study.
Sakai et al [3] have developed an automatic design scheme of railway bogie passenger truck. It adopted an intelligent CAD system using product model. The scheme involves data flow, wherein the designed data is transferred to each subsystem after the fundamental design is completed. Claus et al [4] developed a flexible body model in ADAMS interface to analyze the eigenbehaviour of...