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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Numerical modelling of ti6A14V machining : a combinded FEA and unified mechanics of cutting approach

Bowes, David Christian 03 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: In this study, Ti6Al4V machining is modelled using finite element analysis of orthogonal machining. Orthogonal turning tests are conducted for the verification of FE models in terms of machining forces, temperatures, and chip geometry. Milling force predictions are made using the "unified" mechanics of cutting model which is applied to ball nose milling for this study. The model makes use of orthogonal cutting data, collected from the turning tests, to model milling forces. Model predictions are compared with test data from slot milling tests for verification. Finally a hybrid form of the "‘unified"’ model is presented in which orthogonal data, obtained from the FE simulations, is used to model ball nose milling operations. / AFRIKAANSE OPSOMMING: In hierdie studie word titaanmasjinering (Ti6Al4V) gemodelleer deur gebruik te maak van eindige element analise van ortogonale masjinering. Ortogonale draai toetse word uitgevoer om eindige element (FE) modelle te verifieer in terme van masjineringskragte, temperatuur en spaandergeometrie. Freeskragte word voorspel deur gebruik te maak van die "Unified Mechanics of Cutting" model wat toegepas word op ’n balneusfrees operasie in hierdie studie. Die model maak gebruik van ortogonale snydata, versamel gedurende snytoetse, om die freeskragte te modelleer. Die model word vervolgens vergelyk met die toetsdata afkomstig van die freestoetse vir verifikasie. Ten slotte word ’n hibriede weergawe van die model aangebied waarin ortogonale data verkry word van die FE simulasie om balneus freesoperasies te simuleer.
2

Study on the machinability and surface integrity of Ti6Al4V produced by Selective Laser Melting (SLM) and Electron Beam Melting (EBM) processes / Pas de titre fourni

Milton, Samuel 28 May 2018 (has links)
Les technologies de fabrication additive(FA) basées sur la technique de fusion laser sur lit de poudres, telles que les procédés de fusion sélective laser (Selective Laser Melting ‘SLM’) et de fusion par faisceau d'électrons (Electron Beam Melting ‘EBM’), ne cessent de se développer afin de produire des pièces fonctionnelles principalement dans les domaines aérospatial et médical. Le procédé de fabrication additive offre de nombreux avantages, tels que la liberté de conception, la réduction des étapes de fabrication, la réduction de la matière utilisée, et la réduction de l'empreinte carbone lors de la fabrication d'un composant. Néanmoins, les pièces obtenues nécessitent une opération d’usinage de finition afin de satisfaire les tolérances dimensionnelles et l’état de surface. / Additive Manufacturing (AM) techniques based on powder bed fusion like Selective Laser Melting(SLM) and Electron Beam Melting processes(EBM) are being developed to make fully functional parts mainly in aerospace and medical sectors. There are several advantages of using AM processes like design freedom, reduced process steps, minimal material usage and reduced carbon footprint while producing a component. Nevertheless, the parts are built with near net shape and then finish machined to meet the demands of surface quality and dimensional tolerance.

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