Vibratory rollers are commonly used for compaction of embankments and landfills. This task is time consuming and constitutes a significant part of most large construction and infrastructure projects. By improving the compaction efficiency, the construction industry would reduce costs and environmental impact. This research project studies the influence of the vibration frequency of the drum, which is normally a fixed roller property, and whether resonance can be utilized to improve the compaction efficiency. The influence of frequency on roller compaction has not before been studied but the concept of resonance compaction has previously been applied successfully in deep compaction of fills and natural deposits. In order to examine the influence of vibration frequency on the compaction of granular soil, small-scale compaction tests of sand were conducted under varying conditions with a vertically oscillating plate. Subsequently, full-scale tests were conducted using a vibratory soil compaction roller and a test bed of crushed gravel. The results showed that resonance can be utilized in soil compaction by vibratory rollers and plates and that the optimum compaction frequency from an energy perspective is at, or slightly above, the coupled compactor-soil resonant frequency. Since rollers operate far above resonance, the compaction frequency can be significantly reduced, resulting in a considerable reduction in fuel consumption, environmental impact and machine wear. The thesis also presents an iterative equivalent-linear method to calculate the frequency response of a vibrating foundation, such as a compacting plate or the drum of a roller. The method seems promising for predicting the resonant frequency of the roller-soil system and can be used to determine the optimum compaction frequency without site- and roller-specific measurements. / <p>QC 20160613</p>

The main objective of the project was to develop a model for the motion of granular media under vibration in a tub vibrator. For such a system, it was decided that a discrete element method (DEM) was the most appropriate tool to model bulk velocity and circulation of media. In the first phase of the work, a vibratory finisher was modified to introduce planar vibration into a single layer of particles. The motion of the tub was measured using accelerometers and the corresponding granular media behavior was determined by video recording. A discrete element model, based on Cundall’s approach to contact, was developed to model granular flow in different vibratory beds, and the results were compared with experimental measurements of bulk flow velocity and bed expansion for the tub finisher. The sensitivity of the model predictions to the contact parameters was considered and the parameters were optimized with respect to the experimental results. After optimization, the difference between the model predictions of the bulk flow velocity and the measurements was less than 20% at four locations in media beds of two depths. The average bulk density of the vibrating beds was also predicted to be within 20% of the measured values. In the next phase, a two-dimensional discrete element model was developed to model single-cell circulation in vibratory beds that had both vertical and horizontal components of motion. The model predictions were compared with experimental measurements of the onset and growth of circulation in beds of steel and glass spheres as a function of bed depth, inter-particle and wall friction coefficients, and the amplitude of vibration. While the values from the DEM showed an error of up to 50% in the predicted circulation strength, depending on the type of the media and system conditions, the trends predicted by the model closely matched those in the experiments. Finally, a physical model was developed to describe the relationship between the onset and direction of circulation with the vibration of the container. A similar model was used to describe the experimental results as well as the transition in circulation patterns in terms of the resultant shear forces at the vibrating container walls and the interlocking of media close to the container walls. It was also demonstrated that a two-dimensional DEM could model a granular flow in which the media had three-dimensional contact and freedom of movement, but that was driven by vibrations in a plane. In summary, it was found that the linear optimization procedure for the contact parameters is an efficient way to improve the results from DEM. Additionally, the circulation in a tub-vibrator increased with the depth of the particulate media in the container, and with the magnitude of the wall-particle and particle-particle friction coefficients. The strength of circulation also increased with the amplitude of vibration. A strong correlation existed between the total shear force along the vibrating container walls and the circulation behavior. Bulk circulation increased sharply when increasing bed depth increased the pressure and the shear forces at the walls and between particle layers. It was also concluded that dimensionless bed depth (the ratio of bed depth to particle diameter) was not a proper dimensionless group when discussing the circulation behavior and it should act in conjunction with other parameters.

The main objective of the project was to develop a model for the motion of granular media under vibration in a tub vibrator. For such a system, it was decided that a discrete element method (DEM) was the most appropriate tool to model bulk velocity and circulation of media. In the first phase of the work, a vibratory finisher was modified to introduce planar vibration into a single layer of particles. The motion of the tub was measured using accelerometers and the corresponding granular media behavior was determined by video recording. A discrete element model, based on Cundall’s approach to contact, was developed to model granular flow in different vibratory beds, and the results were compared with experimental measurements of bulk flow velocity and bed expansion for the tub finisher. The sensitivity of the model predictions to the contact parameters was considered and the parameters were optimized with respect to the experimental results. After optimization, the difference between the model predictions of the bulk flow velocity and the measurements was less than 20% at four locations in media beds of two depths. The average bulk density of the vibrating beds was also predicted to be within 20% of the measured values. In the next phase, a two-dimensional discrete element model was developed to model single-cell circulation in vibratory beds that had both vertical and horizontal components of motion. The model predictions were compared with experimental measurements of the onset and growth of circulation in beds of steel and glass spheres as a function of bed depth, inter-particle and wall friction coefficients, and the amplitude of vibration. While the values from the DEM showed an error of up to 50% in the predicted circulation strength, depending on the type of the media and system conditions, the trends predicted by the model closely matched those in the experiments. Finally, a physical model was developed to describe the relationship between the onset and direction of circulation with the vibration of the container. A similar model was used to describe the experimental results as well as the transition in circulation patterns in terms of the resultant shear forces at the vibrating container walls and the interlocking of media close to the container walls. It was also demonstrated that a two-dimensional DEM could model a granular flow in which the media had three-dimensional contact and freedom of movement, but that was driven by vibrations in a plane. In summary, it was found that the linear optimization procedure for the contact parameters is an efficient way to improve the results from DEM. Additionally, the circulation in a tub-vibrator increased with the depth of the particulate media in the container, and with the magnitude of the wall-particle and particle-particle friction coefficients. The strength of circulation also increased with the amplitude of vibration. A strong correlation existed between the total shear force along the vibrating container walls and the circulation behavior. Bulk circulation increased sharply when increasing bed depth increased the pressure and the shear forces at the walls and between particle layers. It was also concluded that dimensionless bed depth (the ratio of bed depth to particle diameter) was not a proper dimensionless group when discussing the circulation behavior and it should act in conjunction with other parameters.

Dissertation (Ph.D.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references (p.283-292).

Contexte de travail Le travail de thèse se déroulera en collaboration entre le CTDEC et le laboratoire GSCOP de Grenoble sous la responsabilité scientifique de Henri PARIS. Le travail de thèse sera co-dirigé opar Joël RECH (MdCf) du laboratoire LTDS en poste à l'ENI de Saint-Etienne. Le travail de thèse s'inscrit dans le cadre d'un projet dénommé FGVV (Forage à Grande Vitesse Vibratoire) soutenu par le FCE (pôles de compétitivité VIAMECA et ARVES INDUSTRIES). Objectifs industriels et scientifiques Ce projet FGVV vise essentiellement à maîtriser et à industrialiser la technologie dite de « forage vibratoire ». Cette technologie permet de réaliser des trous de très grandes profondeurs grâce à une vibration axiale du foret conduisant à une fine fragmentation des copeaux qui s'évacuent alors naturellement sans aucune difficulté. Le projet fait suite à plusieurs années de travaux scientifiques et technologiques, qui ont montré la viabilité technique et économique de ce procédé. L'objectif de cette thèse est d'étendre l'utilisation de cette technologie à des applications concernant des diamètres plus petits et sur des matériaux plus difficile à usiner. Le domaine du décolletage est souvent confronter à des perçages de petit diamètre, voire très petit diamètre (<1mm) dans des matériaux difficile à usiner (acier inox, titane, …). Dans ces applications, l'incidence de l'âme du foret devient importante et les modèles mis en place trouve leurs limites. De plus, les aspects thermiques et tribologiques à l'interface copeau outil ne sont pas simples à maîtriser et génèrent un amortissement qui peut être préjudiciable au bon fonctionnement de la tête de perçage vibratoire. Il s'agit, dans un premier temps, à l'aide de résultats expérimentaux d'identifier les phénomènes liés à coupe de ces matériaux qui sont les plus influents sur le comportement dynamique de la tête de perçage vibratoire. Dans un deuxième temps, cette caractérisation devrait permettre de mettre en place des modèles permettant de prédire le comportement et ainsi d'identifier des points de fonctionnement intéressants. Ces modèles seront alors intégrés dans un outil de simulation permettant de prédire le fractionnement du copeau et plus largement le comportement du système composé de la tête de perçage vibratoire, du foret et de la pièce. Dans un troisième temps, l'extension vers les très petits diamètres nécessite une bonne compréhension et un modélisation de l'amortissement issu de l'âme du foret qui devient prépondérant est nécessaire. Enfin, une optimisation des paramètres autour des points de fonctionnement identifiés permettra de répondre au mieux aux contraintes de productivité. Une re conception de la tête, intégrant ces nouvelles connaissances, est alors prévue pour répondre au mieux aux applications industrielles. Les modèles mis en place devraient aussi permettre une extension vers les applications sur des pièces en alliages d'aluminium moulées car les phénomènes de collage du copeau et son l'incidence sur la comportement dynamique de la tête de perçage vibratoire sont aussi présent sur ce type de matériau. / Background work The thesis work is conducted in collaboration between the laboratory and CTDEC GSCOP Grenoble in the scientific responsibility of Henri PARIS. This thesis will be co-directed by Joël RECH (MdCf) laboratory LTDS stationed in ENI Saint-Etienne. This thesis is part of a project called FGVV (Forage Vibratoire a Grande Vitesse) supported by the CFE (competitiveness clusters VIAMECA and ARVES INDUSTRIES). Objectives industrial and scientific This project focuses FGVV control and industrialize a technology called "drilling vibration." This technology can make holes very deep thanks to an axial vibration of drills leading to fragmentation of a thin shavings which go out then naturally without any difficulty. The project follows several years of scientific and technological work, which demonstrated the technical and economic viability of this process. The objective of this thesis is to extend the use of this technology in applications involving smaller diameters and materials more difficult to machine. The field of cutting is often confronted with small-diameter holes, even very small diameter (<1 mm) in materials difficult to machine (stainless steel, titanium,…). In these applications, the impact of the soul of drills becomes important and models introduced found their limits. In addition, thermal and tribological aspects to the interface chip tool are not easy to control and generate an amortization, which may adversely affect the proper functioning of the head of drilling vibration. In a first step, using experimental results to identify phenomena related to cutting of these materials which are most influential on the dynamic behavior of the head of drilling vibration. In a second time, this characterization is expected to introduce models to predict the behaviour and identify points of operation interesting. These models are then integrated into a simulation tool to predict splitting chip and more broadly the behaviour of the system composed of the head drilling vibration, and the drill room. In a third time, extending to the very small diameters requires a good understanding and modeling of depreciation from the soul of drills that becomes dominant is necessary. Finally, an optimization settings around the operating points identified will best respond to constraints on productivity. A re design of the head, incorporating this new knowledge, is then scheduled to suit the industrial applications. The models put in place should also allow an extension to the applications on parts of aluminum alloy castings as the phenomena of bonding the chip and its impact on the dynamic behavior of the head drilling vibration are also present on this type material.

L’objet de ce travail de thèse consiste à utiliser un formalisme vibratoire pour la détermination de contraintes dans les dépôts à l’aide de la méthode dynamique résonante. Ceci a nécessité le développement d’un formalisme vibratoire adapté aux massifs revêtus, en reliant le niveau de contrainte à la variation des fréquences de résonance mesurées. L’étude a été effectuée en menant trois approches en parallèle : numérique, analytique et expérimentale. En premier lieu, nous avons réalisé des simulations numériques par éléments finis, afin de déterminer la distribution de contraintes dans l’épaisseur d’une poutre composite contrainte et d’évaluer l’effet de ces profils de contraintes sur la fréquence de résonance. Les résultats numériques ont permis d’optimiser le développement d’un nouveau formalisme vibratoire analytique. Pour valider ce dernier formalisme, il nous a fallu l’appliquer sur des dépôts réels,en confrontation avec les résultats d’autres méthodes de mesures de contraintes (DRX/Stoney). Cette confrontation numérique-analytique/expérimentale a révélé que la méthode dynamique résonante est pertinente pour des systèmes de dépôts ayant des rapports d’épaisseur supérieur à0,01. / The aim of this work is to use a new vibratory formalism in order to determine the level of internal stresses in coated materials using the dynamic resonant method. This requires the improvement of vibratory formalism, which allows to link the stress level to the variation of resonance frequency in free flexural mode. This study was conducted by doing three different approaches: numerical, analytical and experimental measurements in real coating. Numerical simulations were conducted by finite element method in static mode to determine the stress distribution in depth. Furthermore, we made other numerical simulations in dynamic mode to evaluate the effect of these static results on the resonant frequency, in comparison with those of coated material without stress. At this stage, these numerical studies let us to develop the vibratory formalism analytically. To validate this latter formalism, we applied it in a real coating for measuring the stress level and we made comparisons with results from others methods(DRX/Stoney). This confrontation (numerical-analytical/experimental measurements) found that dynamic resonant method is efficient for coated material having a thickness ratio moreimportant than 0,01.

Includes bibliography. / The thesis consists of a literature review and a limited experimental investigation in a soils laboratory. The objective of the literature review is to determine what standard laboratory test methods based on vibration exist for the control of compaction, to what soil types these tests are applicable and what the factors are which affect laboratory vibratory compaction. The study revealed that extensive research has been carried out in the USA and Europe, where standard laboratory compaction tests exist for the determination of the maximum dry density of cohesionless, free-draining soil. The US methods are based on the use of a vibratory table, while the European practice is based on the use of a vibratory tamper. No standard tests appear to exist for soil exhibiting cohesion, though limited research has been carried out in the USA into the behaviour of such soils under laboratory vibratory compaction. The factors; frequency, amplitude, mould size and shape surcharge intensity and manner of application, soil type, time of vibration, number of layers and moisture content are all reported to have an effect on the maximum dry density achievable. It has been recognised that significant interaction occurs between the factors affecting vibratory compaction, but the extent of the interaction appears to be only partly understood. The objective of the limited experimental program was to determine whether a specific graded crushed stone could be compacted to Modified AASHTO maximum dry density with a laboratory vibratory compaction technique using a vibratory table, and how this could best be achieved. The effects on dry density of changing the frequency, the time of vibration, mould size, surcharge pressure, grading and moisture content were investigated. It is concluded that the graded crushed stone in question can be compacted to Mod. AASHTO maximum dry density but that before reliable reproducible results can be achieved with this type of test further work is necessary. Such research should be aimed at investigating the interaction effect between the amplitude of vibration, the soil type and the type and intensity of the applied surcharge pressure.

Effective models of vibratory screens which can capture the true response characteristics are crucial in the understanding of faults and failures which occur in vibratory screens. However, the current available models are usually simplified and have limited validation to that of a physical screen. Much research has been conducted to optimise the screening efficiency of screens. The optimisation includes screen geometry, material processing of the screen and the dynamic response of the screen. These investigations have not been furthered to investigate the effects of different faults on the dynamic response of a vibratory screen. To model a vibratory screen which can replicate the dynamics of a physical vibratory screen it is important to create a model with enough complexity to capture the dynamics of the screen. The model of the screen was validated using both modal analysis and the transient response of the screen. The modal analysis was used to ensure that the physical characteristics of the model are consistent with that of the physical screen. Once this was completed, the second validation aimed to investigate if the model of the screen could capture transient faults which are measured experimentally. It was found that it was not possible to conclusively determine if the finite element methods model could Finally, an intelligent method was used to distinguishing between different faults and classifying them accordingly. The intelligent method was also trained using the FEM data and then used to classify the physical screen data. / Dissertation (MEng)--University of Pretoria, 2020. / Mechanical and Aeronautical Engineering / MEng / Unrestricted

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / In order to comply with lima beans peruvian export standards, this study develops an automatic sorter machine. This system uses vibratory conveying to linearly move the grains and to allow their faces to rotate. In addition, image processing algorithms were used for the detection and rejection of defective lima beans. After performing 2200 sorting tests, an industrial performance with an efficiency of 96.81% in acceptance and 95.26% in product rejection was obtained

This study models the compaction of soil by a vibratory roller compactor and examines changes to current designs that may provide more efficient compaction. The modeling of the soil differs from previous analyses of the compaction process in its use of a distributed-parameter characterization of the soil mass and in the application of nonlinear constitutive relations that predict the continuous evolution of residual stresses in the soil. The model was used to determine whether compactor performance might be improved by changes in the forward speed of the compactor or by redistribution of the weight of the frame. No improvement was found to occur. The model was also used to estimate the effects of varying the frequency of vibration to match the evolutionary changes in soil properties during compaction. Hardly any improvement over operation at constant frequency was indicated, but this finding may reflect the tendency of the model to underestimate the rate of stiffening in the soil. / Master of Science