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Under certain cutting conditions carbide tools can sustain a significant amount of permanent deformation and this may cause early tool failure. Tests were devised to investigate the deformation of three different grades of carbide, when machining steel (817M40, EN24) under a wide range of conditions. Each test was carried out on a continuous (60 seconds) and an incremental (5, 5, 10, 20 and 20 seconds) basis. This plan was adopted to investigate transient effects. During each test the cutting forces were measured with a dynamometer, and the boundary temperatures were measured at the tool/chip interface and the tool/shank interface. The permanent deformation took the form of bulging on the flank face and depression of the rake face. With low metal removal rates the deformation was minimal and the cutting edge was stable. High metal removal rates caused the tool to deform continuously and this gave an unstable cutting edge. It was deduced that within the tool there was a zone of material that had undergone plastic deformation. The rake and flank faces formed two external boundaries of this zone, the remaining boundary being within the tool body. For any particular set of cutting conditions, the amount of deformation for either the continuous test or the total of the incremental tests was essentially the same. A plane stress Finite Element (F.E.) model was developed to explain the effects of speed and feed in terms of temperature and stress and their variation with time. The F.E. model predicted that the values of both the transient and steady state thermal stresses were very low when compared with the mechanical stresses. The results from the cutting tests and the F.E. model suggest that the tool material continuously deformed under the applied mechanical stresses (cutting forces). Any contribution to the deformation from the transient thermal stresses was minimal and of a short duration.

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It is well known that high-speed liquid jetting is one of the most powerful techniques available to cut or penetrate material. Recently, it has been conjectured that high-speed liquid jets may be beneficial in improving combustion in such applications as SCRAM jets and direct injection diesel engines. Although there are practical limitations on maximum jet velocity, a fundamental study of the characteristics of high-speed liquid fuel jets and their auto-ignition feasibility is necessary. Important benefits could be increased combustion efficiency and enhanced emission control from improved atomisation. The generation of high-speed liquid jets (water and diesel fuel) in the supersonic to hypersonic ranges by use of a vertical single stage powder gun is described. The effect of the projectile velocity and projectile mass on the jet velocity is found experimentally. Jet exit velocities from a range of different nozzle inner profiles and nozzle hardness are thoroughly examined. The characteristics and behaviour of the high-speed liquid jet and its leading bow shock wave have been studied with the aid of a shadowgraph technique. This provides a clearer picture of each stage of the generation of hypersonic liquid jets. It makes possible the study of hypersonic diesel fuel jet characteristics and their potential for auto-ignition. The fundamental processes by which a supersonic liquid jet is generated by projectile impact have been investigated. The momentum transfer from the projectile to the liquid and the shock wave reflection within the nozzle cavity are the key items of interest. A new one-dimensional analysis has been used in order to simplify this complex and difficult problem. The impact pressure obtained from the projectile was firstly derived. Then, an investigation of the intermittent pressure increase in a closed end cavity and a simple stepped, cross-sectional nozzle were carried out. The nozzle pressure and final jet velocity were estimated and compared to a previous method and to experimental results. Some interesting characteristics found in the experiments relate well to those anticipated by the analysis. The characteristics of a hypersonic diesel fuel jet and its leading edge shock wave were assessed for their potential for auto-ignition using fuel with cetane numbers from 50-100. The investigations were performed at normal ambient air and at elevated air (110 ???C) temperature. So far, there is no sign of auto-ignition that may occur because of the temperature rise of the induced shock.

Thesis (Ph. D.)--University of New South Wales, 2002. / Also available online.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 50-51). Also available via the Internet.

Thesis (Ph. D.)--University of Washington, 1995. / Vita. Includes bibliographical references (leaves [149]-156).

Thesis (Ph. D.)--University of Washington, 1993. / Vita. Includes bibliographical references (leaves [138]-143).

Thesis (Ph. D.)--Lehigh University, 1999. / Includes vita. Bibliography: leaves 115-123.