Thesis (M.Sc.)--City University of Hong Kong, 2000. / "Submitted in partial fulfilment of the requirements for the degree of Master of Science in materials technology and management from City University of Hong Kong." Title from title screen (viewed on Aug. 31, 2006) Includes bibliographical references.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2007. / Singhose, William, Committee Member ; Lee, Kok-Meng, Committee Chair ; Webster, A. Bruce, Committee Member.

No description available.

M.Phil. / Pulleys are critical items in belt conveyors. Their primary role is to drive large mining conveyor systems, facilitating the transportation of ore over extensive distances, both in South Africa and abroad. The effect of the manufacturing process (with specific emphasis on the induced residual stresses) on the fatigue performance of conveyor pulleys is herein investigated and reported. A pre-selected pulley was chosen based on size, suitable for experimental work as well as practical specifications. The static and fatigue performance of the pulley were investigated both with the current design criteria as well as Finite Element Analysis, with comparisons drawn. The material data for the Finite Element Models was obtained experimentally with tensile tests of the SANS 1431 350 WA plate. The magnitude of the residual stresses were obtained experimentally by using the incremental hole-drilling technique for non-uniform residual stresses. The method was verified by comparison with the Finite Element Analysis results for the non-linear material analysis of the roll-bending of the shell. The fatigue analysis revealed that the stress ranges of interest for the pulley were below the non-propagating stress range, and hence theoretically infinite fatigue life would be possible under constant amplitude conditions. The operational fatigue life required for the pulley would be possible, when considering the latest S-N curve for "very high cycle fatigue". The stress intensity factors for the weld details were also below the threshold value and hence crack growth should not occur, upon crack initiation. A new design criteria was proposed for the fatigue analysis considering either fatigue assessment standards or fracture mechanics for the assessment of the butt-welds. This investigation showed that the manufacturing-induced residual stresses may play a significant role in the fatigue life of a pulley. The fatigue strength of a machined stressrelieved joint is higher if the stress range is partly compressive. The fatigue strength of a machined as-welded joint is higher than estimated by the fatigue classifications. This is due to residual stress relaxation that occurs at the weld toe because of yielding and hence a subsequent reduction and redistribution of the residual stresses. This reduction in the mean stress level, with a stress range that is partly compressive, would mean an increase in the fatigue strength of the joint. This would in conclusion result in similar fatigue strengths for a stress-relieved and an aswelded joint. This would additionally depend on the extent of the reduction of the residual stress in the as-welded joint. Recommendations were suggested for further experimental and numerical work for both the T-bottom and Turbine-type pulleys.

Call number: LD2668 .T4 1961 S35

No description available.

Research Doctorate - Doctor of Philosophy (PhD) / Determining the operating parameters and design considerations for dense phase (non-suspension) conveying of fine powders in pneumatic systems typically use empirical, steady-state modelling techniques, as the mechanisms of the flow behaviour are still not fully understood. However, this necessary simplification in the modelling of the dense phase flow still presents significant challenges in ensuring that the predicted outcomes adequately reflect the physical nature of the flow, and therefore provide good design guidance. This thesis represents an examination and development of techniques required for designing dense phase systems of fine powders in three specific areas; prediction of a materials potential to dense phase convey, solids friction correlations and their subsequent effect on pressure drop prediction, and modelling the solids flow from a local perspective. The dense phase capability analysis was conducted by reviewing the current predictive techniques utilising known dense phase material data. It was apparent in the thesis that there were distinct strong predictive regions in all the diagrams; however some diagrams showed areas with weak predictive regions. This work also illustrated the difficulties in comparing different de-aeration rate techniques and significantly, a new mode of flow predictive chart was developed which eliminated the need to determine de-aeration rates while still maintaining distinctly strong dense phase predictive capability. Solids friction based pressure models invariably use a power law which require determination of co-efficient/s and exponent/s. Detailed in this thesis is the research which shows why solutions do not always occur in these power law based friction models and defines a method of determining stable and meaningful values for the exponents. Furthermore, a generic air/particle parameter based solids friction model was developed which is a clear advancement in defining the frictional resistance of dense phase pneumatic conveying of powder. This thesis also proposes a new continuum model which calculates the force balance between the conveying air flow, the resistance of the particles and geometrical effects, like bends. The solution to this model provides qualitative information on fine powder dense phase flow velocity from a solids flow perspective and represents a major step in advancing dense phase modelling from a particle flow basis.

Research Doctorate - Doctor of Philosophy (PhD) / Determining the operating parameters and design considerations for dense phase (non-suspension) conveying of fine powders in pneumatic systems typically use empirical, steady-state modelling techniques, as the mechanisms of the flow behaviour are still not fully understood. However, this necessary simplification in the modelling of the dense phase flow still presents significant challenges in ensuring that the predicted outcomes adequately reflect the physical nature of the flow, and therefore provide good design guidance. This thesis represents an examination and development of techniques required for designing dense phase systems of fine powders in three specific areas; prediction of a materials potential to dense phase convey, solids friction correlations and their subsequent effect on pressure drop prediction, and modelling the solids flow from a local perspective. The dense phase capability analysis was conducted by reviewing the current predictive techniques utilising known dense phase material data. It was apparent in the thesis that there were distinct strong predictive regions in all the diagrams; however some diagrams showed areas with weak predictive regions. This work also illustrated the difficulties in comparing different de-aeration rate techniques and significantly, a new mode of flow predictive chart was developed which eliminated the need to determine de-aeration rates while still maintaining distinctly strong dense phase predictive capability. Solids friction based pressure models invariably use a power law which require determination of co-efficient/s and exponent/s. Detailed in this thesis is the research which shows why solutions do not always occur in these power law based friction models and defines a method of determining stable and meaningful values for the exponents. Furthermore, a generic air/particle parameter based solids friction model was developed which is a clear advancement in defining the frictional resistance of dense phase pneumatic conveying of powder. This thesis also proposes a new continuum model which calculates the force balance between the conveying air flow, the resistance of the particles and geometrical effects, like bends. The solution to this model provides qualitative information on fine powder dense phase flow velocity from a solids flow perspective and represents a major step in advancing dense phase modelling from a particle flow basis.

Thesis (M.S.)--University of Wisconsin--Madison, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The material transport system in an open pit mine significantly affects the capital and operating costs. All truck haulage is the most common and is a reliable and flexible transport system. On the other hand, this system is very expensive and can cost up to 50% of total mining costs. Its cost is continuously increasing due to the inflation of the fuel, tire, and labour expenditures. In-pit crushing and conveying is an alternative transport system which requires a higher initial investment but gives substantial savings in operating costs. An evaluation of the all truck system versus the in-pit crushing and conveying system has been performed by means of a simulation of both transport systems in the same mine model. Results of the simulation and the data obtained from the feasibility studies provided input for an economic comparison of the alternative transport systems. A cash flow analysis showed that the in-pit crushing and conveying system was competitive with the all truck system, giving a payback within four years and resulting in total costs over 30% lower than those of an all truck system. Three computer programs, written by the author, have been used to analyse the mine model: (1) Open Pit Simulation Program - to model a hypothetical mine and simulate its haulage operation over the mine life, (2) Off-Highway Truck Simulation Program - to simulate the truck haulage on average annual routes in terms of the operating time and fuel consumption for the estimation of the truck fleet size and the fuel cost, (3) Cash Flow Analysis Calculation Program - to compare costs of the alternative transport systems over the whole period of a mine life. / Applied Science, Faculty of / Mining Engineering, Keevil Institute of / Graduate