Talking about ultrasonic vibration we can say that it is the essential thing of experimental physics science. The ultrasound is applied amply, for example in: medicine and pharmacy, dimensional and diagnostics devise, mechatronic, mine working, building, automobile and aliment industry, textile industry, connection, energetic – that is not all the actions ranges off people doing, where he is applying. Although hypersonic technologic rise and begin proceed lately, however they are taking the strongest positions in science and technique. Ultrasonic vibration systems (UVS), are designed for push realization, the main function is - interaction with other solid at the dot and to establish the secret elliptical movement trajectory. Also we need a control of this movement, stabilized cooperating with other solids and to keep particular dynamic parameters. Destination of the work: To establish mathematical model of ultrasonic vibration systems (UVS) and to explorer his work dot characterizations. Tasks: 1. Classification, material analysis of existing elliptical movement formative ultrasonic vibration systems (UVS), construction internal, resilient wave spread forms, vibration stimulation tempers. 2. To examine made-up system by finite essential method : determine her vibration parameters – her forms and frequencies; to take measurements of dots, witch formative elliptical trajectory vibration displacement and to establish their movement trajectory. 3. To compare by analytical... [to full text]

Doctor of Philosophy / Department of Industrial & Manufacturing Systems Engineering / Zhijian Pei / Donghai Wang / Both the U.S. and world economies have been depending on petroleum based liquid transportation fuels (such as gasoline, diesel, and jet fuels), which are finite and nonrenewable energy sources. Increasing demands and concerns for the reliable supply of liquid transportation fuels make it important to find alternative sources to petroleum based fuels. One such alternative is cellulosic ethanol. Research, development, and production of cellulosic ethanol have received significant support from both the U.S. government and private investors. However, several technical barriers have hindered large-scale, cost-effective manufacturing of cellulosic ethanol. One such barrier is related to the low density of cellulosic feedstocks, causing high cost in their transportation and storage. Another barrier is the lack of efficient pretreatment procedures, making pretreatment one of the most expensive processing steps and causing efficiency in the subsequent enzymatic hydrolysis to be very low. There is a crucial need to develop more cost-effective processes to manufacture cellulosic ethanol. Ultrasonic vibration-assisted (UV-A) pelleting can increase not only the density of cellulosic feedstocks but also sugar and ethanol yields. It can help realize cost-effective manufacturing of cellulosic ethanol. This PhD research consists of eleven chapters. Firstly, an introduction of this research is given in Chapter 1. Secondly, a literature review on ultrasonic pretreatment for ethanol manufacturing is given in Chapter 2 to show what has been done in this field. Thirdly, a feasibility test on UV-A pelleting of cellulosic biomass is conducted in Chapter 3. Comparisons of the pellet density and sugar yield are also made between pelleting with and without ultrasonic vibration. Next, effects of process variables (such as biomass moisture content, biomass particle size, pelleting pressure, and ultrasonic power) on output variables (such as pellet density, durability, stability, and sugar yield) have been studies in Chapters 4~6. Chapter 7 compares sugar yields between two kinds of materials: pellets processed by UV-A pelleting and biomass not processed by UV-A pelleting under different combinations of three pretreatment variables (temperature, processing time, and solid content). Next, mechanisms through which UV-A pelleting increases sugar and ethanol yields are investigated in Chapters 8 and 9. Then, a predictive model of pellet density is developed for UV-A pelleting in Chapter 10. Finally, conclusions are given in Chapter 11.

Doctor of Philosophy / Department of Industrial & Manufacturing Systems Engineering / Zhijian Pei / Poor machinability of hard-to-machine materials (such as advanced ceramics and titanium) limits their applications in industries. Ultrasonic-vibration-assisted grinding (UVAG), a hybrid machining process combining material-removal mechanisms of diamond grinding and ultrasonic machining, is one cost-effective machining method for these materials. Compared to ultrasonic machining, UVAG has much higher material removal rate while maintaining lower cutting pressure and torque, reduced edge chipping and surface damage, improved accuracy, and lower tool wear rate. However, physics-based models to predict cutting force in UVAG have not been reported to date. Furthermore, edge chipping is one of the technical challenges in UVAG of brittle materials. There is no report related to effects of cutting tool design on edge chipping in UVAG of brittle materials. The goal of this research is to provide new knowledge of machining these hard-to-machine materials with UVAG for further improvements in machining cost and surface quality. First, a thorough literature review is given to show what has been done in this field. Then, a physics-based predictive cutting force model and a mechanistic cutting force model are developed for UVAG of ductile and brittle materials, respectively. Effects of input variables (diamond grain number, diamond grain diameter, vibration amplitude, vibration frequency, spindle speed, and federate) on cutting force are studied based on the developed models. Interaction effects of input variables on cutting force are also studied. In addition, an FEA model is developed to study effects of cutting tool design and input variables on edge chipping. Furthermore, some trends predicted from the developed models are verified through experiments. The results in this dissertation could provide guidance for choosing reasonable process variables and designing diamond tools for UVAG.

Bone cutting is widely used in orthopaedic, dental and neuro surgeries and is a technically demanding surgical procedure. Novel surgical methods are continually introduced in orthopaedic, neuro and dental surgeries and are aimed at minimising the invasiveness of the operation and allowing more precise cuts. One such method that utilises cutting with superimposed ultrasonic vibration is known as ultrasonically- assisted cutting (UAC). The main concern in bone cutting is the mechanical and thermal damage to the bone tissue induced by high-speed power tools. Recent technological improvements are concerned with the efforts to decrease the force required by the surgeon when cutting the bone as well as increases in surgery speed. A programme of experiments was conducted to characterise properties of a bone and get a basic understanding of the mechanics of bone cutting. The experiments included: (a) nanonindentation and tension tests to obtain the properties for the finite element (FE) bone cutting model, (b) high-speed filming to observe the chip formation process, which influences thermomechanics of the cutting process in conventional drilling (CD) and ultrasonically-assisted drilling (UAD) and, (c) plane cutting and drilling experiments to measure the levels of force and temperature rise in the bone tissue. Novel two-dimensional finite element (FE) models of cortical bone cutting were developed for conventional and ultrasonically-assisted modes with the MSC.MARC general FE code that provided thorough numerical analysis of thermomechanics of the cutting process. Mechanical properties such as the elastic modulus and strain-rate sensitivity of the bone material were determined experimentally and incorporated into the FE models. The influence of cutting parameters on the levels of stress, penetration force and temperature in the bone material was studied using conventional cutting (CC) and ultrasonically-assisted cutting (UAC). The temperature rise in the bone material near the cutting edge was calculated and the effect of cutting parameters on the level of thermal necrosis was analysed. The necrosis depth in bone was calculated as a distance from the cut surface to the point where the thermal threshold level was attained. Comparative studies were performed for the developed FE models of CC and UAC of bone and the results validated by conducting experiments and using data from scientific publications. The main outcome of the thesis is an in-depth understanding of the bone cutting process, and of its possible application in orthopaedics. Recommendations on further research developments are also suggested.

Este trabalho tem por objetivo apresentar uma técnica de identificação de falhas em mancais de rolamento até então praticamente inexistente no Brasil. Ela refere-se à mudança da tradicional lubrificação base-tempo, baseada em recomendações de fabricante e fórmulas retiradas de ábacos clássicos para a lubrificação base-condição. Mancais de rolamento são peças obrigatórias em uma infinidade de equipamentos, em sua grande parte, rotativos. A técnica mais difundida de identificação de falhas é a análise de vibração, em seus mais diversos graus de tecnologia embarcada. No entanto, o que ocorre por inúmeras vezes é a identificação da falha já em um estágio onde a falha não pode mais ser reparada, e sim apenas ter seu desenvolvimento monitorado. Isto ocorre devido à freqüência de coleta de dados ser baseada em cartas de severidade, e a falha pode se propagar de uma forma acelerada entre as medições realizadas. A partir desta nova técnica o que se busca é proporcionar à técnica de manutenção preventiva conhecida por lubrificação, que por muitas vezes é tão menosprezada dentro das indústrias, a aquisição de informações importantes a partir de coleta das vibrações ultrassônicas emitidas pelos mancais. Desta forma se fornecem condições para que a lubrificação atue de modo a auxiliar a técnica de análise de vibração, evitando lubrificações em demasia e prevenindo a falta de lubrificante nos mancais, a partir de inspeção baseada em condição. / The aim of this work is to develop a root cause fail identification technique in rolling bearings fairly known in Brazil. This technique refers to the changing from traditional time-based lubrication, done upon manufacturers’ recommendation and formulas taken from classic abacus to condition based lubrication. Rolling bearing are mandatory parts in a large amount of equipments, especially in dynamics. The most known technique for fail identification is vibration analysis, used with different technologies. However several times the identification is made in a stage where the problem can no longer be fixed only monitored. That situation happens because of data collection is made based in severity charts, and fail can propagate in a fast mode between collections. With this condition based technique, it follows to purpose to the other predictive maintenance technique known as lubrication, which is so many cases is undervalued inside industries, the acquisition of important information from bearing ultrasonic vibration data collection. Since this important model apparatus are given to that lubrication acts in order to help vibration analysis technique to avoid over greasing and preventing bearing lack of lubrication, inspection based on condition.

Este trabalho tem por objetivo apresentar uma técnica de identificação de falhas em mancais de rolamento até então praticamente inexistente no Brasil. Ela refere-se à mudança da tradicional lubrificação base-tempo, baseada em recomendações de fabricante e fórmulas retiradas de ábacos clássicos para a lubrificação base-condição. Mancais de rolamento são peças obrigatórias em uma infinidade de equipamentos, em sua grande parte, rotativos. A técnica mais difundida de identificação de falhas é a análise de vibração, em seus mais diversos graus de tecnologia embarcada. No entanto, o que ocorre por inúmeras vezes é a identificação da falha já em um estágio onde a falha não pode mais ser reparada, e sim apenas ter seu desenvolvimento monitorado. Isto ocorre devido à freqüência de coleta de dados ser baseada em cartas de severidade, e a falha pode se propagar de uma forma acelerada entre as medições realizadas. A partir desta nova técnica o que se busca é proporcionar à técnica de manutenção preventiva conhecida por lubrificação, que por muitas vezes é tão menosprezada dentro das indústrias, a aquisição de informações importantes a partir de coleta das vibrações ultrassônicas emitidas pelos mancais. Desta forma se fornecem condições para que a lubrificação atue de modo a auxiliar a técnica de análise de vibração, evitando lubrificações em demasia e prevenindo a falta de lubrificante nos mancais, a partir de inspeção baseada em condição. / The aim of this work is to develop a root cause fail identification technique in rolling bearings fairly known in Brazil. This technique refers to the changing from traditional time-based lubrication, done upon manufacturers’ recommendation and formulas taken from classic abacus to condition based lubrication. Rolling bearing are mandatory parts in a large amount of equipments, especially in dynamics. The most known technique for fail identification is vibration analysis, used with different technologies. However several times the identification is made in a stage where the problem can no longer be fixed only monitored. That situation happens because of data collection is made based in severity charts, and fail can propagate in a fast mode between collections. With this condition based technique, it follows to purpose to the other predictive maintenance technique known as lubrication, which is so many cases is undervalued inside industries, the acquisition of important information from bearing ultrasonic vibration data collection. Since this important model apparatus are given to that lubrication acts in order to help vibration analysis technique to avoid over greasing and preventing bearing lack of lubrication, inspection based on condition.

Este trabalho tem por objetivo apresentar uma técnica de identificação de falhas em mancais de rolamento até então praticamente inexistente no Brasil. Ela refere-se à mudança da tradicional lubrificação base-tempo, baseada em recomendações de fabricante e fórmulas retiradas de ábacos clássicos para a lubrificação base-condição. Mancais de rolamento são peças obrigatórias em uma infinidade de equipamentos, em sua grande parte, rotativos. A técnica mais difundida de identificação de falhas é a análise de vibração, em seus mais diversos graus de tecnologia embarcada. No entanto, o que ocorre por inúmeras vezes é a identificação da falha já em um estágio onde a falha não pode mais ser reparada, e sim apenas ter seu desenvolvimento monitorado. Isto ocorre devido à freqüência de coleta de dados ser baseada em cartas de severidade, e a falha pode se propagar de uma forma acelerada entre as medições realizadas. A partir desta nova técnica o que se busca é proporcionar à técnica de manutenção preventiva conhecida por lubrificação, que por muitas vezes é tão menosprezada dentro das indústrias, a aquisição de informações importantes a partir de coleta das vibrações ultrassônicas emitidas pelos mancais. Desta forma se fornecem condições para que a lubrificação atue de modo a auxiliar a técnica de análise de vibração, evitando lubrificações em demasia e prevenindo a falta de lubrificante nos mancais, a partir de inspeção baseada em condição. / The aim of this work is to develop a root cause fail identification technique in rolling bearings fairly known in Brazil. This technique refers to the changing from traditional time-based lubrication, done upon manufacturers’ recommendation and formulas taken from classic abacus to condition based lubrication. Rolling bearing are mandatory parts in a large amount of equipments, especially in dynamics. The most known technique for fail identification is vibration analysis, used with different technologies. However several times the identification is made in a stage where the problem can no longer be fixed only monitored. That situation happens because of data collection is made based in severity charts, and fail can propagate in a fast mode between collections. With this condition based technique, it follows to purpose to the other predictive maintenance technique known as lubrication, which is so many cases is undervalued inside industries, the acquisition of important information from bearing ultrasonic vibration data collection. Since this important model apparatus are given to that lubrication acts in order to help vibration analysis technique to avoid over greasing and preventing bearing lack of lubrication, inspection based on condition.

Made available in DSpace on 2014-12-17T15:01:25Z (GMT). No. of bitstreams: 1 JoselisseSCS_DISSERT_partes autorizadas.pdf: 100593 bytes, checksum: 6e0be4155f59bdd61810503b91014cbc (MD5) Previous issue date: 2010-11-10 / The objective of this study was to evaluate the displacement of petroleum/diesel solutions, at different concentrations, observing the effect of ultrasonic vibrations in fluids present in porous media to obtain an increase in oil production. The bubbles produced by ultrasound implode asymmetrically in the rock, generating liquid jets with high speed, displacing the oil present in porous media. The oil/diesel solutions were prepared with concentrations ranging from 20 g/L to 720 g/L in oil in relation to diesel and its viscosities were obtained in a Brookfield Rheometer RS2000, with temperature ranging from 25 to 55 ?C. After, calculations were performed to obtain the activation energy data for oil/diesel solutions. For oil recovery experiments, cylindrical samples of porous rock (core samples), with resin around the perimeter and its two circular bases free to allow the passage of fluids, were first saturated with 2% KCl solution and after with oil solutions. The results of oil extraction were satisfactory for all studied solutions, being obtained up to 68% partial displacement with saline solution injection. The ultrasound system was used after saline injection, increasing oil displacement, with oil extractions ranging from 63% to 79%. During the experiments, it was observed the warming of core samples, helping to reduce the viscosity of more concentrated systems, and consequently enhancing the percentage of advanced recovery for all studied solutions / O objetivo desse trabalho foi avaliar o deslocamento de solu??es de petr?leo/diesel, em diferentes concentra??es, observando o efeito das vibra??es ultrass?nicas no deslocamento dos fluidos presentes em meio poroso para obter um aumento na produ??o de petr?leo. As bolhas formadas pelo ultrassom implodem na rocha de forma assim?trica, gerando jatos de l?quido em alta velocidade, deslocando o ?leo do meio poroso. As solu??es foram preparadas em concentra??es variadas de 20 g/L a 720 g/L em ?leo com rela??o ao solvente diesel e suas viscosidades analisadas em um Re?metro Brookfield RS2000, com intervalos de temperaturas de 25 a 55 ?C. Em seguida, foram realizados c?lculos para obten??o dos dados de energia de ativa??o das solu??es ?leo/diesel. Para a realiza??o dos experimentos de recupera??o de petr?leo foram utilizadas amostras de rochas porosas cil?ndricas (plugs) resinadas na lateral deixando as extremidades livres para a transposi??o dos fluidos at? a satura??o, inicialmente com solu??o de KCl (2%) e posteriormente com as solu??es de petr?leo. Foram obtidos resultados satisfat?rios da extra??o para todas as solu??es estudadas, obtendo-se um deslocamento parcial por meio de inje??o salina de at? 68%. Ap?s este estudo foi utilizado o sistema de ultrassom, que ajudou ainda mais no deslocamento final, obtendo-se extra??es que variaram entre 63% e 79% de petr?leo. Durante os experimentos ocorreu um aquecimento nos plugs, que auxiliou na diminui??o da viscosidade dos sistemas mais concentrados, e consequentemente aumentou os percentuais de recupera??o avan?ada para todas as solu??es estudadas