Browsing by Author "Cuperus, Jacobus Louwrens"
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- ItemEffects of modelling simplifications in FEA of railway wheels(Stellenbosch : Stellenbosch University, 2017-03) Cuperus, Jacobus Louwrens; Venter, Gerhard; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.ENGLISH ABSTRACT: Typically, as part of the specifications outlining the requirements of railway wheels, the supplier must demonstrate through finite element analysis (FEA) that the design can withstand certain operational conditions and load cases. The specifications focused on in this study are the Transnet Freight Rail RS/ME/SP/008 specification for the supply of cast trailing stock wheels as well as the RS/ME/SP/021 specification for the supply of wrought wheels for tractive and trailing stock. These specifications contain a section pertaining to the finite element analysis of the wheel with respect to certain operational conditions. These conditions involve, however, complex interactions between loading and material non-linearities, superimposed onto a complex initial stress field. This stress field is laboriously obtained through a heat treatment schedule designed to induce compressive residual hoop stress in the rim of the wheel. These complexities are ostensibly routinely ignored in the application of these (and similar) standards. This study aimed to provide some engineering and scientific reasoning to the simplification of these complex analyses in the future by investigating the effects of various assumptions and simplifications on the FEA. The stress distribution of the normal contact loads are obtained through numerical simulation. The data is also used to derive a simple contact model for contact between two specific wheel and rail profiles. Residual stresses of the new wheel was determined by simulating the heat treatment process. These models were also used to investigate the modelling details required to get accurate results from such a simulation by selectively applying various simplifications to the model. The convective heat transfer to the atmosphere was investigated with computational fluid dynamic simulations and the data fitted to a non-dimensional heat transfer model. This data was then also compared to published heat transfer models of simplified flow scenarios in order to determine if any of these is a viable option to determine heat transfer behaviour in the future. Finally, all of the data gathered with the other analyses were used to determine the effect of various simplifications on the analysis as prescribed in the Transnet standards.