Vibration compaction is the most effective way of compacting coarse-grained materials. The effects of vibration frequency and amplitude on the compaction density of different backfill materials (No. 4 natural sand, No. 24 stone sand and No. 5, No. 8, No. 43 aggregates), were studied in this research. The test materials were characterized based on the particle sizes and morphology parameters using digital image analysis technique. Small-scale laboratory compaction tests were carried out with variable frequency and amplitude of vibrations using vibratory hammer and vibratory table. The results show an increase in density with the increase in amplitude and frequency of vibration. However, the increase in density with the increase in amplitude of vibration is more pronounced for the coarse aggregates than for the sands. A comparison of the maximum dry densities of different test materials shows that the dry densities obtained after compaction using the vibratory hammer are greater than those obtained after compaction using the vibratory table at the highest amplitude and frequency of vibration available in both equipment. Large-scale vibratory roller compaction tests were performed in the field for No. 30 backfill soil to observe the effect of vibration frequency and number of passes on the compaction density. Accelerometer sensors were attached to the roller drum (Caterpillar, model CS56B) to measure the frequency of vibration for the two different vibration settings available to the roller. For this roller and soil tested, the results show that the higher vibration setting is more effective. Direct shear tests and direct interface shear tests were performed to study the impact of particle characteristics of the coarse-grained backfill materials on interface shear resistance. A unique relationship was found between the normalized surface roughness and the ratio of critical-state interface friction angle between sand-gravel mixture with steel to the internal critical-state friction angle of the sand-gravel mixture.

Main subject of this diploma thesis is design proposal of walk-behind vibratory roller which is a part of the light compaction technology. The proposal brings different design solution from existing products in the current market and it is aimed on the ergonomics and machine handling.

Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Compaction is one of the key processes in the construction of road pavement layers. Not only is it significant in ensuring the structural integrity of the material in the road layers, but it also has an influence on the engineering properties and performance of the soil material. A poorly compacted material is characterised by low density, high porosity and below standard shear strength. This, as a result causes rutting, moisture susceptibility, potholing, corrugations and passability problems on the road. Therefore, it is vitally important that field compaction is done correctly. For this reason, laboratory compaction methods have been developed to simulate the field compaction process in the laboratory. The Mod AASHTO test has long been used as the laboratory compaction method of choice by virtue of its simplicity and the lack of bulky equipment required. However, previous studies have established that the Modified AASHTO method does not adequately simulate field compaction criteria especially for cohesionless materials. Two reasons have been advanced; The Mod AASHTO compaction method does not adequately simulate the compaction done in the field when the granular mix is laid; The compaction method may cause disintegration of the material. Alternative tests have been considered and much research has focused upon the use of a modified demolition hammer (vibratory hammer) for laboratory compaction of granular materials. This study undertook to evaluate the influence of test factors pertinent to the vibratory hammer compaction method. The influence of these test factors on compaction time and obtainable material density was assessed with the objective of developing a compaction method for granular materials. Vibratory hammer compaction tests were conducted on G3 hornfels, G4 hornfels and G7 sandstone material types and to a lesser extent, reclaimed asphalt (RA). Densities obtained were referenced to Mod AASHTO compaction density. Findings of the study showed that, the mass of the tamping foot has a significant influence on the obtainable compaction density. Other factors such as, moisture content, frequency and frame rigidity were also found to affect compaction with the vibratory hammer. In addition, it is shown that the surcharge load does not significantly influence the obtainable compaction density but does contribute to the confinement of the material and restricts the upward bounce of the hammer. On the basis of the results and findings, a compaction method was proposed, incorporating test parameters and factors that would provide ideal results for a set compaction time. Repeatability tests showed that, the developed vibratory hammer compaction method was effective in compacting graded crushed stone material types (i.e. G3 and G4) and probably RA. The test was not as effective on the G7 material. Further studies on this material (G7) are required. In addition to the previous testing regime, a comparative assessment of the developed vibratory hammer compaction method in relation to the vibratory table method was done. The results show that the vibratory hammer is capable of producing specimens of densities comparable to those of the vibratory table. A sieve analysis undertaken before and after compaction showed that compaction with the developed vibratory hammer compaction method does not result in any significant material disintegration. Based on the results of this study, a specification for the determination of maximum dry density and optimum moisture content of granular material using the vibratory hammer is recommended. / AFRIKAANSE OPSOMMING: Kompaksie is een van die belangrikste prosesse in die konstruksie van die padplaveisel. Dit is nie net waardevol vir die versekering van strukturele integriteit van die materiaal, maar dit het ook 'n invloed op die ingenieurseienskappe en vermoë van die grond materiaal. 'n Swak gekompakteerde materiaal word gekenmerk deur 'n laë digtheid, hoë porositeit, on onvoldoende skuifweerstand. Die kenmerke maak die material vatbaar vir vogen. Lei tot spoorvorming, slaggate, golwe en deurgangs probleme op die pad. Dit is dus uiters noodsaaklik dat veld kompaksie korrek gedoen word. Om hierdie rede, is kompaksie metodes in die laboratorium ontwikkel om sodaend veldkompaksie te simuleer. Die “Mod AASHTO” laboratorium kompaksie toets is die gekose laboratorium kompaksie metode op grond van sy eenvoudigheid en gebruik van minimale toerusting. Vorige studies het egter bevestig dat die “Mod AASHTO”-metode nie veldkompaksie akkuraat kan simuleer nie, veral vir kohesielose materiaal. As gevolg van twee hoofredes; Die Mod AASHTO kompaksiemetode is nie ‘n realistiese en vergelykende simmulering van kompaksie soos dit in die veld gedoen word nie; Die kompaksie metode mag verbrokkeling van die materiaal veroorsaak. Alternatiewe toetse was oorweeg en baie navorsing het gefokus op die gebruik van 'n aangepaste vibrerende hamer. Hierdie studie het onderneem om verskeie relevante toetsfaktore van die vibrerende hamer en hul invloed op die kompaksie en verkrygbare digtheid te bestudeer. Die invloed van hierdie toetsfaktore op kompaksietyd en verkrygbare materiaal digtheid was geassesseer met die doel om 'n kompaksiemetode vir granulêre materiaal te ontwikkel. Vibrerende hammer kompaksietoetse was uitgevoer op G3 hornfels, G4 hornfels en G7 sandsteen materiaal en tot 'n mindere mate herwinde asfalt. Digthede verkry was verwys na die Mod AASHTO kompaksie digtheid. Resultate van die studie het getoon dat die gewig van die stamp voet ‘n merkwaardige invloed het op die verkrygbare kompaksie digtheid. Ander faktore soos voginhoud, frekwensie en raam styfheid het ook getoon om kompaksiedigtheid te beïnvloed met die vibrerende hammer. Benewens was ook getoon dat die toeslaglading geen beduidende invloed het op die verkrygbare kompaksie digtheid nie, maar wel bydrae tot die inperking van die materiaal en verhoed die vertikale terugslag van die hammer. Gebaseer op die resultate en bevindinge was ‘n kompaksiemetode voorgestel wat toets parameters integreer met toetsfaktore en tot volg ideale resultate vir ‘n gegewe kompaksietyd voorsien. Herhaalde kalibrasie toetse het getoon dat die ontwikkelde kompaksiemetode effektief is in die kompaktering van gegradeerde gebreekte klip materiaaltipes (G3 en G4) en moontlik herwanne asfalt. Die toets was nie so doeltreffend op die G7 materiaal nie. Verdere studies op hierdie materiaal (G7) is dus nodig. Addisioneel tot die vorige toets, is bevind dat ‘n vergelykende assesering van die ontwikkelde vibrerende hammer kompaksiemetode in verhouding tot die vibrerende tafel. Die resultate wys dat die vibrerende hammer die vermoë het om toetsmonsters met digthede vergelykbaar met die vibrerende tafel te produseer. Sifanalise voor en na kompaksie het getoon dat verdigting met die ontwikkelde vibrerende hamer kompaksie metode nie lei tot die disintegrasie van die materiaal nie. Gebasseer op die resultate van dié studie was ‘n spesifikasie vir die bepaling van maksimum droé digtheid en optimale voginhoud van granulêre material aangeraai.

This work deals with the possibility of use of intelligent methods in construction machines control. These methods are based on GPS in combination with using laser and ultrasonic technology. There is in detail described especially control by robotic total station and 3D control, which includes digital model of construction site. The new trends of control are especially applied on the vibratory rollers. There are taken into consideration: achievement of sufficient degree of compaction on the basis of on-line information about conditions of subsoil.

Le roulement est l'un des composants les plus importants des machines tournantes. Néanmoins, dans des conditions normales d'utilisation, il est soumis à de la fatigue de roulement qui peut conduire à un défaut d'écaillage. Dans ce travail, nous présentons un suivi de la fatigue d'un roulement de butée grâce à un banc d'essais dédié. L'analyse vibratoire est une méthode qui permet de caractériser et de localiser les défauts dans les roulements. Des mesures successives de ces niveaux de vibrations donnent des indications quant à l'évolution de la sévérité des défauts. Le suivi de cette évolution est fait grâce à un indicateur statistique, la valeur RMS (Root Mean Square) qui peut être corrélée avec la taille d'un écaillage de roulement. L'approche suit le fonctionnement du roulement de butée jusqu'à la dégradation avec une acquisition on line des états vibratoires sous forme de signaux temporels. A l'aide du traitement de signal, on obtient les valeurs des amplitudes vibratoires qui caractérisent l'état vibratoire du roulement. Par conséquent, ces valeurs nous permettent de tracer les courbes de fatigue. Au cours de notre travail expérimental, cette opération est appliquée à un lot de butées à billes pour lesquelles nous avons obtenu des courbes semblables où la tendance de l'évolution suit un modèle mathématique à partir de la détection de l'apparition de la première écaille. Le résultat de ce travail contribuera à prédire la durée de vie résiduelle avant la panne. / The bearing is one of the most important components of rotating machines. Nevertheless, in normal conditions of use, it is subject to fatigue which creates a defect called a rolling fatigue spalling. In this work, we present a follow-up of the thrust bearing fatigue on a test bench. Vibration analysis is a method used to characterize the defect. In order to obtain the fatigue curve more adjusted, we have studied the vibration level according to statistical indicators: the Root Mean Square value (RMS value), which is one of the best indicators to show the evolution of the bearing degradation. The approach follows the working of the bearing until the degradation with an on line acquisition of vibration statements in form of time signals. With the signal treatment, we obtain the values of the vibration amplitudes which characterize the vibration state of the bearing. Consequently, these values allow us to plot the fatigue curves. During our experimental work, this operation is applied for a batch of thrust bearings for which we have obtained similar fatigue curves where the evolution trend follows a mathematical model from the detection of the onset of the first spall. The result of this work will contribute to predict the working residual time before failure.

Concepção, desenvolvimento de projeto e fabricação de um mini-moinho vibratório para cerâmica avançada. Diversas áreas de engenharia são hoje dependentes de componentes de cerâmica avançada. A conformação da cerâmica, baseada na compactação de pós, seguida de sinterização, tem encontrado diversas aplicações em processos de manufatura dos produtos cerâmicos avançados. Tamanhos de partículas pequenas (abaixo de 1 \'mü\'m) e controle da distribuição granulométrica são desejáveis, porque aumentam a reatividade das partículas cerâmicas. O presente projeto busca pela concepção de um moinho que processe pequena quantidade de material em múltipla moagem no atendimento das necessidades de ambientes de trabalho de desenvolvimento e fabricação de peças especiais tais como os laboratórios e indústrias de pequeno porte. Normalmente os moinhos encontrados no mercado são para escalas maiores e moagem simples. Dessa forma, baseado em técnicas de metodologia de projeto, principalmente na busca de soluções para a concepção e desenvolvimento, tanto do sistema \"moinho vibratório\", quanto dos jarros, procurou-se desenvolver um procedimento para um projeto adaptativo de moinho vibratório. Foi projetado e construído um moinho para moagem simultânea de seis jarros com volume útil de moagem de 20 a 300 mL em cada jarro. Foram realizadas moagens de alumina de tamanho médio inicial de 5,2 \'mü\'m as quais foram analisadas em sedígrafo. Foram obtidos pós com 0,7 \'mü\'m de diâmetro médio equivalente e pós com 18% abaixo de 0,2 \'mü\'m. / Conception, project development and manufacture of a vibratory mini-mill for advanced ceramics. Diverse areas of engineering today are dependent on advanced ceramic components. The ceramic conformation, based on powder compaction, and followed by sintering, has been found to have many different applications in manufacturing process in advanced ceramic products. Small size particles (below 1 \'mü\'m) and the control of particle size distribution are desirable, as they increase the reactivity of ceramic particles. The present project involves a search for the conception of a mill that process small amounts of material in multiple milling to meet the requirements of research laboratories and small industries. Normally the mills available on the market are for larger scale and simple, milling. Therefore based on techniques of project methodology, mainly in brainstorming for conception and development, not only on the \"vibratory mill system\" but also on the jars, it was developed a procedure for an adaptable project for a vibratory mill. A mill for the simultaneous milling of six jars with milling volume from 20 to 300 mL on each jar was projected and built. Alumina with medium particle size of 5.2 \'mü\'m, were milled using the \"vibratory mill system\" and analyzed by sedigraph. After milling the particles had an average diameter of 0.7 \'mü\'m with 18% of the particles below 0.2 \'mü\'m.

The surface-normal impact velocity distributions, impact frequencies and impact power per unit area were measured using a force sensor in a vibratory finisher for two types of spherical media. These parameters control the degree, rate and character of plastic deformation of a workpiece surface in vibratory finishing. The force sensor was also used to quantify the effect of media type, finisher amplitude, and location within the finisher on the probability distribution of the particle impact velocity normal to the workpiece. It was found that reducing the total media mass in the finisher and moving closer to the wall resulted in a more aggressive process. It was also found that contacts occured periodically within time periods that corresponded to the finisher’s driving frequency. The Almen system was adapted to a vibratory finishing process to characterize the effect of varying process parameters for the purposes of process development and control. Saturation curves for two types of aluminum Almen strips were obtained by finishing at two distinct conditions. Comparison with the normal contact forces and effective impact velocities, measured for both these conditions, provided insight into the mechanics of the vibratory finishing process. An electromagnetic apparatus was constructed to simulate the normal impacts in the vibratory finisher. It was found that surface-normal impacts at velocities comparable to the higher range in the vibratory finisher produced Almen saturation curves similar to those created in the vibratory finisher. This provided support for the modeling approximation of treating all contact events in a vibratory finisher as effective surface-normal impacts, and the accuracy of the effective impact velocity measurement. A model of the process by which Almen strips were plastically deformed by media impacts in vibratory finishing was presented. The motivation was to extend the use of Almen strip measurements as a means of characterizing vibratory finishing through an improved understanding of the process parameters that controlled time-dependent curvature development. Two thicknesses of Almen strip were tested for two finishing conditions. The quantitative agreement between the model saturation curves and the experimental curves was fair, although the overall trends were predicted very well.

The surface-normal impact velocity distributions, impact frequencies and impact power per unit area were measured using a force sensor in a vibratory finisher for two types of spherical media. These parameters control the degree, rate and character of plastic deformation of a workpiece surface in vibratory finishing. The force sensor was also used to quantify the effect of media type, finisher amplitude, and location within the finisher on the probability distribution of the particle impact velocity normal to the workpiece. It was found that reducing the total media mass in the finisher and moving closer to the wall resulted in a more aggressive process. It was also found that contacts occured periodically within time periods that corresponded to the finisher’s driving frequency. The Almen system was adapted to a vibratory finishing process to characterize the effect of varying process parameters for the purposes of process development and control. Saturation curves for two types of aluminum Almen strips were obtained by finishing at two distinct conditions. Comparison with the normal contact forces and effective impact velocities, measured for both these conditions, provided insight into the mechanics of the vibratory finishing process. An electromagnetic apparatus was constructed to simulate the normal impacts in the vibratory finisher. It was found that surface-normal impacts at velocities comparable to the higher range in the vibratory finisher produced Almen saturation curves similar to those created in the vibratory finisher. This provided support for the modeling approximation of treating all contact events in a vibratory finisher as effective surface-normal impacts, and the accuracy of the effective impact velocity measurement. A model of the process by which Almen strips were plastically deformed by media impacts in vibratory finishing was presented. The motivation was to extend the use of Almen strip measurements as a means of characterizing vibratory finishing through an improved understanding of the process parameters that controlled time-dependent curvature development. Two thicknesses of Almen strip were tested for two finishing conditions. The quantitative agreement between the model saturation curves and the experimental curves was fair, although the overall trends were predicted very well.

The objective of this research dissertation is to design and implement two novel micromachined silicon vibratory gyroscopes, which attempt to incorporate all the necessary attributes of sub-deg/hr noise performance requirements in a single framework: large resonant mass, high drive-mode oscillation amplitudes, large device capacitance (coupled with optimized electronics), and high-Q resonant mode-matched operation. Mode-matching leverages the high-Q (mechanical gain) of the operating modes of the gyroscope and offers significant improvements in mechanical and electronic noise floor, sensitivity, and bias stability. The first micromachined silicon vibratory gyroscope presented in this work is the resonating star gyroscope (RSG): a novel Class-II shell-type structure which utilizes degenerate flexural modes. After an iterative cycle of design optimization, an RSG prototype was implemented using a multiple-shell approach on (111) SOI substrate. Experimental data indicates sub-5 deg/hr Allan deviation bias instability operating under a mode-matched operating Q of 30,000 at 23ºC (in vacuum). The second micromachined silicon vibratory gyroscope presented in this work is the mode-matched tuning fork gyroscope (M2-TFG): a novel Class-I tuning fork structure which utilizes in-plane non-degenerate resonant flexural modes. Operated under vacuum, the M2-TFG represents the first reported high-Q perfectly mode-matched operation in Class-I vibratory microgyroscope. Experimental results of device implemented on (100) SOI substrate demonstrates sub-deg/hr Allan deviation bias instability operating under a mode-matched operating Q of 50,000 at 23ºC. In an effort to increase capacitive aspect ratio, a new fabrication technology was developed that involved the selective deposition of doped-polysilicon inside the capacitive sensing gaps (SPD Process). By preserving the structural composition integrity of the flexural springs, it is possible to accurately predict the operating-mode frequencies while maintaining high-Q operation. Preliminary characterization of vacuum-packaged prototypes was performed. Initial results demonstrated high-Q mode-matched operation, excellent thermal stability, and sub-deg/hr Allan variance bias instability.

Made available in DSpace on 2014-06-11T19:27:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-08-12Bitstream added on 2014-06-13T19:34:58Z : No. of bitstreams: 1 santos_ch_me_guara.pdf: 2207083 bytes, checksum: 6c810376924fcd84cb5a78acf9dd1896 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A estampagem de chapas metálicas é importante e se destaca entre os processos de conformação, pois, é possível de se obter vários produtos com alta produtividade e baixo custo. No entanto, como todo processo de conformação pode haver alguns inconvenientes, como as tensões residuais, que são geradas devido ao aumento da resistência mecânica do material resultante da deformação plástica a frio ou devido à geometria complexa da peça, com regiões de tração e compressão. Algumas medidas são realizadas dentro da área fabril para minimizar o problema e assim as peças irem para a etapa seguinte de conformação. Uma delas é a realização de tratamento térmico de alívio das tensões residuais de forma manual. O problema é que esse processo não garante nenhum controle da microestrutura e também não há garantia que as tensões foram aliviadas e como consequência peças são sucateadas na etapa seguinte de conformação, acarretando um aumento maior dos custos de fabricação. Neste trabalho foi realizado um estudo do alívio das tensões residuais através de vibrações mecânicas abaixo da frequência de ressonância em uma peça estampada a frio. O objetivo deste trabalho é avaliar os efeitos das vibrações mecânicas abaixo da frequência de ressonância no alívio das tensões residuais, de tal forma que possa ser uma opção ao tratamento térmico. Os resultados mostram que ouve redução nas tensões residuais, porém novos estudos devem ser realizados para garantir a eficácia deste processo / The stamping of sheet metal is important and stands out among the forming processes, therefore it is possible to obtain various products with high productivity and low cost, however, the whole process of conformation can bring some drawbacks, such as residual stresses, that are generated due the rigidity of the material against cold plastic deformation or due the geometry complex of the piece, with areas on tension and compression. Some processes are carried out within the factory area to minimize the problem and so the pieces go to the next step of forming, for instance perform heat treatment relief residual stresses. The problem is that this process does not guarantee any control of the microstructure and also there is not guarantee that the tensions were reduced and failure pieces in the next step of conformation, resulting in a greater increase in manufacturing costs. In this paper has been studied relief residual stress by mechanical vibrations, with carry out of treatment relief from vibrations below the resonant frequency in component cold drawned. The objective of this study is to evaluate the effects of mechanical vibration below the resonant frequency to relieve residual stresses, so that might be an option to heat treatment. The results show a reduction in residual stress; however, we have to compare them with other treatments for which they can ensure the effectiveness of mechanical vibrations