Mechanical Engineering - Theses
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ItemAssembly line sequencing for product-mix( 1971)This thesis is concerned with the sequencing of various models of a product when these are manufactured on one assembly line using product-mix. A simplified model of the assembly line is postulated. Four heuristic algorithms are developed which aim at minimizing assembly line length while avoiding operator interference. Two of these algorithms are used in a factorial experiment to determine the relationship between assembly line length and five factors. These factors are characteristics of the production requirement and workload balance. From the experimental results, empirical equations are developed which are a useful aid in the design of new assembly lines or the balancing of existing assembly lines. The experimental results are also analyzed to determine a range of sequencing problems for which near optimal sequences can be expected using the two algorithms.
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ItemThe form drag of two-dimensional bluff-plates immersed in turbulent shear flows( 1965)The literature concerning bluff-body flows in two-dimensional, incompressible, sheared and unsheared streams is reviewed. It is found that no theory yet exists which can predict the form drag of a bluff body without some recourse to experimental data, even for the simple case of an isolated bluff-plate in an unsheared stream. In the present state of knowledge, and considering the complexity of turbulent shear flows, a theory for the form drag of bluff-plates immersed in turbulent boundary-layers seems remote. A correlation scheme is proposed to relate the form drag of a bluff-plate which is attached to a smooth-wall with the mean-flow characteristics of the naturally-developed, turbulent boundary-layer in which it is immersed. The investigation is limited to smooth-wall flows of the type described by Coles (1956). It is suggested that, for bluff-plates which are small compared with the boundary-layer thickness, the drag might depend only on the “wall variables”: wall shear-stress, fluid density and viscosity, and the plate height.
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ItemThe four bar linkage as a function generator( 1960)Part I: A new concept of the synthesis of the four bar linkage as a function generator is presented. Existing methods of synthesis are examined in the light of this concept, and their advantages discussed. The basis for a new method of synthesis is presented. Part II: A machine which mechanically allows finding the by trial four bar linkage whose polodes are most nearly like the curves which generate the given function exactly has been constructed and calibrated. The apparatus is described and the conditions which indicate a solution are stated. Proof that these conditions are a solution is given. Two simple graphical methods of approximate synthesis have been developed and are used to minimize the trial and error required.
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ItemAn introduction to brown coal distillation: the German "schwelung von braunkohle"( 1955)After the successful production of hard charfrom Yallourn brown coal had been demonstrated on the laboratory scale in this Brown Coal Research Laboratory by F. A. Bull in 1953, attention began to be turned to extending the process to a larger scale and to the possible design of a full size carbonization plant. In October 1953, the author was requested by Professor Henderson to give some consideration to the carbonization of brown coal briquettes for the production of hard char in Victoria, particularly with regard to: 1.The economic of the process. 2. A suitable type of carbonization retort. 3. The recovery of by-products. Professor Henderson was particularly interested in a design of carbonization retort which would enable high calorific value carbonization gas to be recovered and sold as a by-product for town supply. It was to review these questions that this report was prepared. Further, however, the author found that existing literature in the English language gave only a very narrow picture of the practice of brown coal carbonization and nothing of the principles underlying the practice. The report was therefore designed to provide at the same time an introduction to these principles and practice for the benefit of any reader interested in the carbonization of brown coal. The author was very fortunate here in being able to secure a copy of a prospectus published by the Lurgi Gesellschaft which gave a first class description of their Circulating Gas Distillation Process, and has translated it from the original German to form Part I of the report.
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ItemThe design of engineering products( 1963)This thesis examines the design of engineering products. Its purpose is to clarify the role of design in engineering, to give a general description of the design process, and to emphasise aspects of the subject which are not widely recognized, or if recognized are not applied. in practice because of the designer's preoccupation with the rush of day-to-day problems. Parts of the thesis inevitably reflect a bias towards the author's experiences as a mechanical design engineer in privately owned industries where the products were manufactured in small or medium-sized batches. This bias is most clearly evident in chapter 3, but also appears in sections of chapters 2 and 4. All in all, a broad perspective has been adopted with the intention that the thesis should cover a wide range and not be confined to the interests of a special branch of engineering. For this reason the word “engineering” in the title has not been qualified in any way. After giving considerable thought to this subject the author came to the conclusion that there was scope for bringing together in one paper the ideas and concepts which are of major importance in engineering design. All too often these are not appreciated by the individual designer, because references to them are widely scattered throughout the literature or because he allows himself to be immersed in the minutiae of his work.
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ItemCavitation in hydraulic machinery: its influence on the design of impellers for centrifugal and axial-flow pumps( 1963)This thesis considers aspects of rotating hydraulic machinery of the centrifugal, mixed-flow, and axial-flow types; wherever the word "pump" is used without any qualifying adjective it is understood that it is a generic term which includes all these types. The objective is to present and discuss the methods available for the design of pump impellers for cavitating or near-cavitating conditions. In order to give an orderly and logical account of this subject the thesis opens with a description of cavitation in hydrodynamics, and this is followed by an examination of its mechanism and of the physical factors which affect it. Model experiments are an important tool in assisting the designer predict performance and one chapter is therefore devoted to a discussion of model laws and scale effects in cavitation. Chapters 4 and 5 deal with the detailed design of impellers for non-cavitating and cavitating flows, while the final chapter evaluates this work and draws some general conclusions.
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ItemInvestigation on the milling process( 1968)Metal cutting is a complex production process involving plastic deformation and tool-chip friction under unusual conditions of strain, strain-rate and stress. Since late last century workers from various parts of the world have attempted to develop analytical models that could reasonably well represent the observed phenomena. A number of analyses have evolved but these are mainly concerned with the simple orthogonal cutting process at constant depth of cut. These analyses, although not in complete agreement with experimental results, are similar, and call give a qualitative account of the observed trends. Included in those analyses area number of fundamental parameters which could prove useful in predicting quantitative results for orthogonal cutting and may possibly be used for other more practical cutting operations. The aim of this work is to extend the thin shear zone theory of cutting to the milling process with particular reference to up milling with zero helix angle cutters. Thus a geometrical analysis of the milling process and an evaluation of the undeformed chip thickness as defined by the theory of cutting is required. Due consideration of the wedge angle, rake angle and clearance angle variations is also required. To obtain the experimental data for a quantitative analysis, equipment has to be developed to measure the basic quantities in metal cutting i.e. the instantaneous cutting force variation and chip deformation. The experimental data collected will be analysed in accordance with the developed theory and it is hoped that the resulting trends will be similar to those known for constant depth orthogonal cutting.
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ItemA study of the preparation of coke by the carbonization of brown coal briquettes( 1954)In all industrialized countries coal is a most important source of energy and an essential raw material for the metallurgical and heavy chemical industries. Where there is little or no oil and a low hydro-electric potential its position is dominant. The four great nations, the United States, the Soviet Union, Germany and Great Britain, could not have become pre-eminent in industry and technology if they had not possessed abundant supplies of coal, particularly bituminous or coking coal. Although coal is used extensively as a fuel in homes and factories, the largest quantities are consumed for the generation of electricity, the production of town gas, the firing of railway locomotives and the preparation of metallurgical coke. Except in Germany these processes have utilized black coal almost exclusively. In the State of Victoria, however, the reserves of black coal are a mere 6 million tons whereas those of brown coal amount to 45,000 million tons according to a recent estimate by Herman (loc. cit. p.89). This means that for self-sufficiency in fuel Victoria must seek to do with brown coal what other countries have done with black. Much has already been achieved. Most of the electricity generated in this State comes from power stations burning either raw or briquetted brown coal. A large plant for completely gasifying brown coal briquettes is at present being erected at Morwell to augment the supply of town gas to Melbourne. The Victorian Railways have recently demonstrated that steam locomotives can be efficiently fire with pulverized brown coal. There remains then the task of making a solid non-volatile from brown coal to take the place of the coke obtained black coal. The work described in this thesis is a contribution to the solution of this problem. (From Introduction)
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ItemA study of the drilling process( 1970)The modern two flute twist drill has been in existence for more than fifty years and the drilling process has become one of the most widely used manufacturing operation. There has hardly been any major alteration in the general appearance of the twist drill despite the various studies on the effect of geometry on drill performance such as tool life and cutting forces. Nevertheless a better understanding of the capabilities and limitations of the twist drill has been made possible by these investigations. The twist drill generates holes by the cutting action of the lips and the indenting action of the chisel edge. The geometry of the lips has been generalized to that of a lathe tool and the cutting action of the lips was reported as similar to single edged oblique cutting. A cutting model for drilling has not been developed possibly because of the complex geometry of the lips and the extruding action of the chisel edge, which is difficult to study. As a result many empirical equations for the prediction of forces have been proposed. In this project the geometry of the various size drills will be studied. Analyses of the mechanics of drilling will be attempted in the hope that a cutting model may be constructed based on established principles of orthogonal and oblique cutting. This is desirable since in the design and application of drilling, like in other topics of metal cutting) it is useful to be able to predict the deformation and cutting forces.