Thesis (Ph.D.)--McMaster University, 2005. / Supervisors: M.A. Elbestawi, G.M. Bone. Includes bibliographical references (leaves 117-122).

Thesis (MEng)--University of South Australia, 1995

Thesis (M.Eng.(Mechanical Engineering))--University of Pretoria, 2004. / Summaries in Afrikaans and English. Includes bibliographical references (leaves 80-82).

No description available.

The aim of this thesis is to provide academic support to the oldest discipline of Mechanical Engineering, namely "Machine Design". The rapid pace of technological development drives every individual, especially students. The industrial revolution in the first half of the 19th century contributed greatly to the advancement of Mechanical Engineering. The theories and experimental data from that time, some developed almost a hundred years ago are still in use in the original form while others have evolved to keep up with the times. This thesis attempts to bring some of that classical machine design theory into a modern user-friendly form that is portable across the Internet. Here the user will be presented with an interactive menu of topics of Machine Design where each is split sub-categorically as Theory and Application. According to the choice made, short excerpts of theory are presented on the chosen matter. The theory will include but not be limited to the important relationships relevant to the design of the particular machine element. After the review of the Theory, the user will be able to navigate to the application where the relationships from the theory will be awaiting user input in the form of solvers. Since the primary emphasis of the thesis is about cultivating knowledge of the underlying theory, the applications will not be self-correcting or self-assuming. The user will need to understand the relationships sufficiently well prior to using the applications to solve homework or design assignments. The created Toolbox is available to all registered users through a login access. The user can then choose to review theory or directly access the applications of the described theory. The thesis successfully demonstrates the use of the Internet as the media for education. / Master of Science

The principal objective of the research programme was to develop a technique for monitoring the condition of power-press cutting tools using ultrasonics. The principle of the technique was based upon the reflection of Surface Acoustic Waves (SAWs) from the tooling's cutting edges, and the main aim of the research was to establish the relationship between reflected SAW amplitude and tool edge condition. Three approaches were used to establish the relationship, namely on-line experiments, off-line bench-top experiments, and mathematical modelling. The modelling work involved using Transmission Line Modelling. Three types of wear were observed on the punch: i. The formation of a wear radius on the cutting edge of the punch. ii. The beating back of the bottom face of the punch adjacent to the cutting edge. iii. The formation of an abraded region on the flank of the punch adjacent to the cutting edge. The research has shown that it is possible to monitor the radius that forms on the cutting edge of the punch using the amplitude of SAW pulses reflected from the edge. Also the work has indicated that the rate of radius formation is a function of the clearance between the punch and the die. However, the effects of the change in the cutting edge's condition on the propagation delay of the SAWs, which was also investigated, was not found to be significant. Whilst in principle it should be possible to automatically monitor the condition and predict the wearing out of press-tools, the development of a working tool-moni toring system capable of monitoring the complete cutting edge of a press-tool is presently being hindered due to the lack of a suitable transducer.

A five degrees of freedom analysis of a perfect precision grinding spindle supported by a pair of back to back angular contact ball bearings is performed. The ball to race contacts are simulated by a non-linear contact spring, representing the elastic deformation of the mating rolling members. Major frequencies associated with various degrees of freedom are observed and a number of design curves, suggesting the best zones of operation for the simulated spindle under radial/ axial loading are also presented. The gyroscopic contribution of an ideal precision spindle was found to be insignificant. The model was further expanded to study the response characteristics of the spindle under lubricated contact conditions. A regression formula is used to model the non-linear spring/ damper arrangement,corresponding to the contact elastohydrodynamic oil film thickness. It is noted that the presence of the oil film along the line of contacts do not significantly alter the position of the major modes of the system. However, its contribution in damping the amplitude of oscillation are found to be significant. Various graphs indicating the overall system response, subjected to varying oil film viscosity, number of balls and the spindle mass are also presented. Furthermore, experimental investigations are conducted to validate the employed methodology. Good agreement is observed between the results of the simulation and the experimental spectra for the fundamental modes of response. Although manufacturing anamolies are not simulated,the formulated models incorporate sufficient versatility to forsee various spindle/bearing configurations, different loading arrangement as well as various geometrical features of a system to be modelled.

Review of the literature clearly illustrated the need for more information on journal bearings operating in the transition vortex regime. Especially in the light of recent information indicating that many real applications may be operating in this region and to date most consideration has been given to fully turbulent studies. Accordingly, an experimental test rig was designed to measure torque and both circumferential and axial pressure profiles. The test bearing was circular and of central circumferential supply groove design. LID ratio was 0.25 for each land and a clearance ratio of 0.00307 used to conform with "real" modelling of high speed bearings. Lubricant inlet and outlet temperature were measured (with Rem based on the latter) together with shaft speed and displacement. Three lubricants were used, Tellus 22, Tellus RIO and water to allow a Reynolds number range of 30 - 10, 000 to be covered, and thus encompassing lamina_r, transition and turbulent flow regimes. Low Reynolds number results agreed well with laminar theory and transition from laminar to vortex flow was observed to occur around the speed predicted by Taylor. In the transition region, inertial effects were found to be very small but were taken into consideration for all comparisons between theory and experiment. Existing super laminar theories were in poor agreement with experiment. An empirical theory based on friction factor results was developed including inertia and led to much improved estimates of circumferential pressure distribution. The best agreement being observed in the mid transition region were a "hump" in the friction factor v's Reynolds number results had been measured. Due to the method of measuring pressure profiles interesting observations are reported on cavitation phenomena.

No description available.

No description available.