In order to simulate the histories of temperature distributions and plastic flow of the dwell phase during a friction stir welding process, the Newton-Raphson method is used to solve the simultaneous equations of energy and momentum in the cylindrical-coordinate system. Comparing the simulation with the results of experiment, results show that the contact condition between the tool and the workpiece is at pure sliding without plastic flow at the beginning of the dwell phase until the temperature rises to about 300¢XC at the depth of 1.5 mm. In this period, the heat generation comes from the sliding friction between two surfaces. After the plastic flow occurs, the heat generation rises rapidly, and then decreases to a saturated value so that the temperature rise also achieves a constant value. Thermal expansion of the workpiece will increase the plunge force, so that the heat generation and the temperature raise increase. At the steady state condition, with increasing sticking proportion, the heat generation and the temperature quickly achieve a saturated value. For the steady-state condition, results show that the speed of plastic flow and shear strain rate increase with increasing rotational speed. The control of the contact state variable can effectively describe the heat generation and the distribution of plastic flow in different contact conditions. Comparing the simulation with the results of experiment, the contact condition can be identified.

Micro Air Vehicles (MAV’s) have small size and extreme maneuverability which makes them ideal for surveillance. Propulsion mechanisms include propellers, rotors, and flapping airfoils. Flapping motions, along with biologically-inspired wing profiles, are of interest due to their use of natural physics. Corrugated airfoil structures appears to have poor aerodynamic performance at higher Reynolds numbers, but serve well at Re<10,000. Understanding flow structures around corrugated profiles and comparing them to a standard airfoil will aid in understanding how these corrugated profiles perform well and have been adopted by some of nature’s most acrobatic flyers. Motivation for this investigation is to compare static flow visualizations of corrugated profiles to a standard National Advisory Committee for Aeronautics (NACA) airfoil from low to high angles of attack and further observe flow structure development of a pitching and plunging flat plate at a Re<10,000 and a Strouhal number relevant to natural fliers. The static visualization was conducted at Re=1,000 with a NACA 0012 airfoil and two corrugated models. The Pitch and Plunge Fixture (PPF) developed was constructed by simplifying flapping wings as a two degree of freedom motion in plunge (translation) and pitch (rotation). Results obtained from the PPF were compared with a numerical simulation.

The Giant and Con deposits, Yellowknife, Northwest Territories, represent a classic Archean lode-gold deposit now offset by a major Proterozoic fault (West Bay Fault). The link between the Giant and Con deposits is supported by their similarities. However, there are distinct differences between the two deposits in terms of the offset of stratigraphy, response to D2 deformation, geometry, gold mineralization styles, and depth of gold mineralization. Gold mineralization in the Giant-Con system formed over a protracted history of deformation and hydrothermal activity. Early D1 extension resulted in offset and excision of stratigraphy and the formation of refractory gold mineralization within strongly deformed schistose zones and quartz-carbonate veins. The main D2 deformation in the district resulted in the strong overprint of D1 refractory gold mineralization and was associated with the northwest-southeast flattening of the Giant deposit and progressive reverse-dextral shear of the Con deposit. Free-milling gold mineralization is associated with the D2 event, forming deeper in the Giant-Con system, creating a vertical zonation of free-milling quartz-carbonate veins overprinting earlier refractory gold mineralization that formed higher in the system. Ore plunge in the Giant deposit is controlled by the interaction of the original geometry of D1 deformation zones with the effects of D2 flattening. Ore plunge in the Con deposit is controlled by the orientation of F2 fold and B2 boudin axes in auriferous quartz-carbonate veins. D3 reactivation of the deformation zones (probably related to the end of the D2 compressive event) caused local reactivation of structures and is not associated with gold mineralization. D4 Proterozoic faulting offset and segmented the two deposits, including the major offset by the West Bay Fault. A new reconstruction of the West Bay Fault shows that the Con deformation zone is the down dip extension of the Giant deposit and not the Campbell deformation zone as previously thought.

The hydrodynamic characteristics of the Baihetan Plunge pool and the impact of changing the secondarydam’s top elevation was investigated. Quantities such as the velocity distribution, turbulencedissipation rate, water surface profile and the probability of a submerged jump forming in the plungepool was studied.The numerical model showed in general good agreement with data gathered from an experimentalstudy conducted in 2012. The only exception was the maximum pressure in the plunge pool, whichwas 16.91 % higher for the simulation using a top elevation of 604 MASL for the secondary dam. Theuse of a grid convergence index (GCI) showed that the result was closer to being mesh independentin the plunge pool (GCIplunge = 4:5 %), but not in the jet body (GCIjet = 16:9 %).The results indicated that no significant improvement was given for changing the top elevationof the secondary dam to 604 or 606 MASL (original height is 602 MASL) since all cases displayflow pattern indicating that a submerged jump will occur. Moreover most of the turbulence wasconcentrated near the jet for all the cases, indicating that the plunge pool is properly designed forthe purpose it is intended to do, i.e. dissipating the energy of the jets in the plunge pool and notdownstream to the unprotected riverbanks.The main conclusion is that the original design is to prefer since no advantages is given byheightening the secondary dam, and will only increase the cost of construction.

Submitted by Rubens Chinali Canarim null (rubenscanarim@hotmail.com) on 2018-02-05T12:10:04Z No. of bitstreams: 1 TESE FINAL ENTREGA.pdf: 2914880 bytes, checksum: e1503c15204b7dbc230efbbea4f1320d (MD5) / Approved for entry into archive by Maria Marlene Zaniboni null (zaniboni@bauru.unesp.br) on 2018-02-05T15:53:59Z (GMT) No. of bitstreams: 1 canarim_rc_dr_bauru.pdf: 2914880 bytes, checksum: e1503c15204b7dbc230efbbea4f1320d (MD5) / Made available in DSpace on 2018-02-05T15:53:59Z (GMT). No. of bitstreams: 1 canarim_rc_dr_bauru.pdf: 2914880 bytes, checksum: e1503c15204b7dbc230efbbea4f1320d (MD5) Previous issue date: 2018-01-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A presente tese estudou a influência da friabilidade de dois rebolos de CBN (alta friabilidade – HF e baixa friabilidade – LF) na retificação cilíndrica externa de mergulho do aço AISI 4340, temperado e revenido, para vários avanços. Os resultados obtidos demonstraram que, comparativamente, o rebolo de baixa friabilidade (CBN LF) fornece melhor acabamento para a peça em termos de rugosidade e desvios de circularidade, com menor desgaste de rebolo, em todos os avanços. Por outro lado, o consumo de potência e seus sinais de emissão acústica foram sempre mais elevados. Para a tensão residual, a baixa friabilidade auxilia na geração de tensões compressivas na peça. Todavia, mesmo com a alta friabilidade, para condições mais agressivas de corte também é possível obter tensões compressivas elevadas. Nenhuma das condições de usinagem alterou a microestrutura das peças retificadas, com base nos resultados de microdureza Vickers. A elevada friabilidade, de um modo geral, pode promover fratura excessiva dos grãos, que acabam por aumentar o riscamento e deteriorar a qualidade superficial das peças, além de desgastar mais o rebolo, em virtude do predomínio da macrofratura sobre a microfratura. Ao mesmo tempo, contudo, reduz as forças de corte e o consumo de potência. Deve-se levar em conta todos os fatores à disposição para efetuar a melhor escolha de rebolo e sua friabilidade para determinada aplicação. / The present thesis aimed to study the influence of friability of two CBN wheels (high friability – HF and low friability – LF) on the external plunge cylindrical grinding of the AISI 4340 steel, quenched and tempered, for different feed rates. The results showed that CBN LF provided better workpiece finishing in terms of surface roughness and roundness deviations, with lower wheel wear, in all feed rates. However, power consumption and acoustic emission signals were always higher than for CBN HF. For residual stresses, low friability contributes to the generation of compressive stresses on the workpiece. For high feed conditions, even CBN HF can provide high compressive stresses. None of the grinding conditions caused alterations on the workpiece microstructure, based on the results for Vickers microhardness. High friability can promote excessive grain fracture, which can increase scratching and deteriorate the surface quality, causing higher wheel wear as well (since macrofracture predominates over microfracture). On the other side, it can reduce cutting forces and power consumption. All factors at disposal must be taken into account in order to conduct the optimal selection of grinding wheel– as well as its adequate friability – for each specific application.

This master thesis has been conducted at Svea Teknik on behalf of Atlas Copco and deals with the design of a cutter head motion system for mechanical rock excavation machines. Mechanical rock excavation allows tunneling to be done with just one machine in a continuous process. Such a machine is called a tunnel boring machine (TBM) and excavates rock by pressing a rotating cutter head with disc cutters against the rock face. By moving the cutter head in different patterns, tunnels of different profiles and sizes can be excavated. Atlas Copco has currently a conceptual TBM with an associated cutter head motion solution attached. The main task of this master thesis is to examine if an alternative solution to this motion system could be incorporated to the conceptual TBM, and to develop this solution to a functional concept design. In order to find a suitable alternative design nine concepts where generated and evaluated against the current concept solution using a weighted PUGH-matrix. The chosen concept was refined into a final functional concept design. The produced concept design consists of a two part linkage arm construction connected via a cylindrical joint. At one end of the articulated arm the cutter head is located and at the other end the linkage arm is connected to a rotatable base which allows the arm to rotate and swing to the sides. This rotatable base is in later turn supported by a base structure mounted to the main body of the current concept machine. All motion is achieved by hydraulic cylinders which are mounted in their respective ends using spherical bearings to minimize the need of narrow tolerance spans. The benefits of this alternative design are a greater choice of tunnel profiles along with simpler bearing solutions which may reduce manufacturing- and service costs. The downside is instead added weight to the front of the machine which will move the center of mass closer to the cutter head. This may have a negative effect on the machine propulsion system. / Detta examensarbete har utförts på Svea Teknik på uppdrag av Atlas Copco och behandlar utvecklingen av ett rörelsesystem för förflyttningen av borrhuvudet på maskiner för mekanisk bergavverkning. Med mekanisk bergavverkning är det möjligt att gräva ut en tunnel med bara en maskin i en kontinuerlig process. En sådan maskin kallas tunnelborrningsmaskin (TBM) och bryter berget genom att ett borrhuvud med brytskivor rullar under tryck mot bergsväggen. Genom att förflytta borrhuvudet i olika mönster kan tunnlar med olika profil och storlek anläggas. Atlas Copco har för närvarande en konceptuell TBM med tillhörande lösning för borrhuvudförflyttningen. Huvuduppgiften för detta examensarbete är att undersöka om en alternativ lösning till detta förflyttingssystem kan integreras med denna TBM och att utveckla den här lösning till en funktionell konceptdesign. För att hitta en lämplig alternativ utformning har nio koncept tagits fram vilka utvärderas mot den befintliga konceptlösningen i en viktad PUGH-matris. Det valda konceptet har förfinats till en slutgiltig funktionell konceptdesign. Det framtagna konceptet består av en tvådelad länkarmskonstruktion sammansatta via en cylindrisk rotationsled. I ena änden av länkarmen är borrhuvudet monterat och vid den andra änden är länkarmen ansluten till en roterbar bas som möjliggör att länkarmarna kan rotera och svänga åt sidorna. Denna roterande bas är i sin tur upphängd i en basstruktur som är fastmonterad på den nuvarande konceptmaskinen. All rörelse uppnås genom hydraulcylindrar som är monterade i respektive ände med hjälp av sfäriska lager för att minimera toleranskraven. Fördelarna med detta alternativa koncept är en större frihet i valet av tunnelprofiler tillsammans med en enklare lagerlösning som kan minska tillverknings- och servicekostnader. Nackdelen är istället att vikten längre fram på maskinen ökar. Detta leder till att masscentrum flyttats närmare borrhuvudet vilket kan ha negativ inverkning på maskinens framdrivningssystem.

The purpose of this research was to use the Transvalor S.A. product, Forge3, to develop a finite element simulation of the friction stir welding process that improves the predictability of temperature evolution and material flow within the plunge portion of the process. Previous modeling created more heating within the billet than experimental results, probably due to the simplification of the simulation with adiabatic boundary conditions. More realistic tooling temperatures were included in this model as these affect heat evolution which is a determining factor in microcrystalline growth. These results were validated by experimental efforts using a billet and tooling instrumented with thermocouples used to evaluate the temperatures at specific locations over time. Simulation results were compared with previous experiments to validate the predicted material flow.

This dissertation aims to contribute toward the understanding of water-entry and -exit behaviors in nature. Since water is nearly a thousand times denser than air, transitioning between the two mediums is often associated with significant changes in force. Three topics with implications in water-entry are discussed, along with a fourth topic on water-exit. For a plunge-diving seabird, the first two stages of water-entry (initial impact and air-cavity formation) create large stresses on the bird's neck. Linear stability analysis of a cone-beam system impacting water shows buckling and non-buckling behaviors on the beam, which is extended to the diving birds. The next topic is related to the third stage of water-entry (air-cavity pinch-off), in which the chest feathers come in contact with the water. Here, the elasticity of Northern Gannet contour feathers is calculated using the nonlinear bending equation. The third topic will explore the formation of ripples along air cavity walls and their resulting force after pinch-off. An acoustic model predicts the observed wavelengths of the ripples. The final topic will delve into the mechanics of how animals leap out of water. A scaling law that balances the power of thrust and drag will predict the height of the jump. Finally, a bio-inspired robot was built to help identify physical conditions required to jump out of water. / Ph. D.

Heat transfer augmentation is of paramount importance in energy transfer and storage systems and the idea of using the inherent vibrations in a system to enhance heat transfer needs to be thoroughly researched upon. The current study numerically investigates an infinitesimally thin plate-fin undergoing forced oscillations over a range of amplitudes and frequencies in the presence of an approach flow. Reduced frequencies of 0.25 ≤ k ≤16 and plunge amplitudes of 0.03125 ≤ h ≤ 8 are investigated at Re=100 and Pr = 0.71. It is shown that the combined effect of frequency and amplitude on heat transfer enhancement can be accounted for as a single parameter “plunge velocity” (0.25 ≤ kh ≤ 4) instead of the individual frequency and amplitude values. For kh > 0.5 a significant increase in Nusselt number ( is observed compared to a stationary plate. With increasing kh or more vigorous oscillations, the increase in becomes more prominent and similar trends and comparable magnitudes were observed for a constant value. Unlike the hydrodynamic counterpart of the study, both Leading Edge Vortices (LEVs) and Trailing Edge Vortices (TEVs) are found to act positively to induce enhanced heat transfer on the plate. Finally, the dependence of heat transfer augmentation on the frequency and amplitude of vibration is quantified with a simple parameterization for a plate-fin in a fluid medium. / M.S. / Heat transfer enhancement is of paramount importance in energy transfer and storage systems. The idea of using the inherent mechanical vibrations in a heat producing system to enhance transfer of unwanted heat from that system needs to be thoroughly researched upon. To investigate this idea, we numerically study an infinitesimally thin plate-fin undergoing forced oscillations over a range of amplitudes and frequencies in the presence of an incoming air flow. It is shown that the combined effect of frequency and amplitude on heat transfer enhancement can be accounted for as a single parameter called “plunge velocity” instead of the individual frequency and amplitude values. For a significant plunge velocity, a significant increase in Nusselt number ( is observed compared to a stationary plate representing an increase in the extent of heat transferred. With more vigorous oscillations, the increase in becomes more prominent and similar trends and comparable magnitudes were observed for a constant value. Finally, the dependence of heat transfer augmentation on the frequency and amplitude of vibration is quantified with a simple parameterization for a plate-fin in a fluid medium.

Made available in DSpace on 2014-06-11T19:30:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-03Bitstream added on 2014-06-13T19:39:45Z : No. of bitstreams: 1 simoes_rp_dr_bauru.pdf: 3105631 bytes, checksum: 49bc95b3c3c78388d520425875d9eabb (MD5) / Atualmente há por parte das empresas uma constante preocupação com a atualidade de seus sistemas produtivos, buscando a melhoria da eficiência dos processos respeitando as leis de preservação ambiental. Dentro desse contexto e considerando que o segmento das cerâmicas corresponde a aproximadamente 1% do PIB brasileiro, com perspectiva de crescimento, inúmeros estudos têm sido feitos nesse campo de pesquisa. Contudo, ainda se tem um alto custo agregado ao acabamento da peça, o qual é feito, na maioria dos casos, pelo processo de retificação. Além do alto custo do processamento, o uso de fluidos de corte tem se tornado um problema para a indústria devido à dificuldade de descarte imposta pela rígida Legislação Ambiental. Face ao exposto, o presente trabalho propõe o estudo de métodos alternativos de lubri-refrigeração para o processo de retificação externa de mergulho de cerâmica avançado com rebolo diamantado. Tais métodos visam diminuir os gastos com fluido de corte, sendo eles: a técnica de lubri-refrigeração otimizada e a de mínima quantidade de lubrificação (MQL). A avaliação das técnicas foi feita através do monitoramento do processo e da quantidade final da peça retificada. Mais especificamente, foram analisados: força tangencial de corte, rugosidade, relação G, desvio de circularidade, microestrutura e tensão residual por difração de raios X. Os resultados obtidos mostram que as duas técnicas propostas podem substituir o método convencional de lubri-refrigeração, destacando-se que a técnica otimizada reduziu o desgaste do rebolo e produziu pelas com melhor acabamento geométrico e dimensional, enquanto a técnica de MQL reduziu significativamente a quantidade de fluido utilizado no processo / During the last years there has been a constant concern by the companies about the modernization of their manufacturing methods, seeking to improve the process efficiency and environmental preservation. In this context, and considering the ceramic segment corresponds to approximatelly 1% of Brazilian GDP, with growing perspective, many studies have been done in this area. Nevertheless, the work piece finishing is still expensive, mainly because it has been usually made by the grinding process. Besides of the high cost of the process, the use of cutting fluids has become a problem for the industry because of the discard dificulty imposed by the rigorous environmental laws. In this way, the present work proposes alternative methods for the lubrification and cooling in the external cylindrical plunge grinding of advanced ceramic with diamond wheels, which aims to reduce the costs with cutting fluid. These methods are: the optimized cooling and the Minimal Quantity Lubrication (MQL) techniques. The evaluation of these techniques has been made by the process monitoring and the work piece final quality. In the present work the following analysis techniques were used: tangential cut force, roughness, G relation, circularity deviation, microstructure and residual stress by X ray diffraction measurements. The results show both proposed techniques can replace the conventional cooling method. The main result is that the optimized technique reduced the cutting tool consuming and produced work pieces with better dimensional finishing, while the MQL techniques significantly reduced the volume of cutting fluid in the process