Thesis (M.A.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains v, 173 p. Includes abstract. Includes bibliographical references (p. 169-173).

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19236号 / 工博第4071号 / 新制||工||1628(附属図書館) / 32235 / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 西脇 眞二, 教授 松原 厚, 准教授 小森 雅晴 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

This thesis was submitted to the School of Graduate Studies in partial fulfillment of the requirements for the Degree Master of Applied Science. / <p>Accuracy and surface finishes play an important role in modem industry. However, the deformability of ductile materials induces challenges in achieving high accuracy and surface finish. Undesired projections of material produced during metal cutting, known as burrs, significantly reduces the accuracy of the parts and affect both the assembly process and product quality. Around 30% of total production costs are used for deburring processes. This thesis presents one modem and promising method in reducing burr size through the use of ultrasonic assistance. With ultrasonic assistance, high frequency vibrations are added in the feed direction during cutting. In particular, ultrasonic assisted drilling of 1100-0 aluminum using high speed steel standard twist drills was investigated.</p> <p>Two simulation studies were conducted. Firstly, a finite element model of orthogonal cutting with and without ultrasonic assistance was developed. The results predicted that ultrasonic assistance should produce smaller burrs for the simulated operating conditions. Secondly, a drilling exit burr model was created based on a circular plate deflection model. Unfortunately this simulation failed to predict the experimentally observed burr sizes and thus the model requires further development.</p><p>To provide the ultrasonic vibration a preloaded workpiece holder and a drive circuit were designed and implemented for use with a commercial piezoelectric actuator. This equipment was cost effective (costing about 400 CAN$) and functional.</p><p>The effects of ultrasonic assistance under different vibration and cutting conditions were investigated experimentally. The experimental results demonstrated that, for certain combinations of vibration frequency and amplitude, burr size reduction can be achieved. Under these conditions the ultrasonic impact actions become significant, causing chip segmentation and smaller burrs. The results also show that ultrasonic assisted drilling allows a higher spindle speed and feed to be used without increasing burr size. However, ultrasonic assistance has a negative impact on tool life. Compared with conventional drilling, chipping of the chisel edge and greater wear of the cutting lips was observed after drilling 10 holes. This situation may be improved in the future if drills with suitable coating are used in place of the standard high speed steel drills.</p> / Thesis / Master of Engineering (ME)

This thesis presents a short biography of Aaron Burr followed by a look at his controversial political life from 1783-1804.

Burrs are rough protrusions that form along the edge of a component during processing and are commonly produced during machining. Generally, the presence and severity of a burr directly impacts the final part quality. Thus, burrs need to be removed in subsequent processes to avoid injury when handling a part and/or negatively impacting the part's functionality. The size, shape, and nature of the attachment of the burr to the cutting edge are highly dependent on the material, tooling, and process parameters used during machining. This research aimed to develop two new approaches to minimize and/or eliminate burr formation during the drilling of ductile materials. The first new method outlined in this thesis relates to injecting materials in different forms at high pressures under the workpiece on the side from which the drilling tool exits to support the drilling thrust force and thereby minimize exit burr formation. The second method introduced a novel technique for designing and testing highly effective step drills based on the workpiece material and cutting parameters, using commercial drills. Testing the two approaches showed promising results for producing comparatively smaller exit burrs. / Thesis / Master of Applied Science (MASc)

Burrs severely inhibit the performance and aesthetics in machined parts besides posing a safety risk to the user and manufacturer. Abrasive assisted brushing presents a fast and effective method for deburring these parts but is difficult to control. The dependence of deburring rate on the workpiece material, abrasive grit size, type and rotational speed of the brush is studied. It is found that deburring rate is proportional to initial burr height indicating fracture of the burr at the root. Deburring rate increases with spindle speed and is higher for diamond than SiC. The formation of burrs in micromilling of a thin nickel-titanium alloy (nitinol or NiTi) foil used in implantable biomedical device applications is analyzed as a function of micromilling process parameters such as spindle speed, feed, tool wear, backing material and adhesive used to attach the foil to the backing material. All factors except spindle speed are found to affect burr size. If initial penetration is sufficient to cause the foil to fail in tension, the foil tears with the crack starting closer to the upmilling side and thereby resulting in larger downmilling burrs. If penetration is insufficient, the foil plastically deforms until it tears typically in the middle of the cutter tooth path. A kinematic model that captures this behavior is used to predict burr widths and is verified through experiments. The thesis also presents an investigation of the abrasive impregnated brush deburring process for thin NiTi foils. Models based on Hertzian indentation and fracture mechanics are proposed to predict the rates of indentation and deburring during brushing and are validated using experiments. The predictions of the models are within the experimental variation. Burrs can be removed with this process within 12 minutes for a 6 mm long groove with no more than a micron change in foil thickness. Knowledge of burr formation and deburring is applied to a novel micromilled thin shape memory based NiTi foil device used for the surgical correction of Age-related Macular Degeneration (AMD), a leading cause of blindness in the western world in those over age 50. Burrs on the surface of the structure are used successfully to mechanically constrain and translocate an autograft to replace the diseased RPE-Bruch's membrane under the macula. The shape memory device is analyzed using experiments and simulations.

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Estatística, 2017. / Submitted by Raiane Silva (raianesilva@bce.unb.br) on 2017-07-18T15:47:02Z No. of bitstreams: 1 2017_VanessaSilvaResende.pdf: 1790290 bytes, checksum: 2113a9e077de5258cc6628ebcb59784a (MD5) / Approved for entry into archive by Raquel Viana (raquelviana@bce.unb.br) on 2017-08-31T21:45:10Z (GMT) No. of bitstreams: 1 2017_VanessaSilvaResende.pdf: 1790290 bytes, checksum: 2113a9e077de5258cc6628ebcb59784a (MD5) / Made available in DSpace on 2017-08-31T21:45:10Z (GMT). No. of bitstreams: 1 2017_VanessaSilvaResende.pdf: 1790290 bytes, checksum: 2113a9e077de5258cc6628ebcb59784a (MD5) Previous issue date: 2017-08-31 / A censura intervalar ocorre quando não se conhece o tempo de sobrevivência exato, sabe-se somente que ocorreu em um intervalo de tempo. De outra forma, quando todos os indivíduos são avaliados nos mesmos intervalos de tempo, ocasionando muitos empates, têm-se dados grupados. Portanto, os dados de sobrevivência grupados são casos particulares da censura intervalar. Neste trabalho, foi proposto um modelo de regressão para dados de sobrevivência grupados utilizando a distribuição log-beta Burr III, cuja principal característica é a possibilidade da função taxa de falha assumir diferentes formas (crescente, decrescente, unimodal). Posteriormente, foi proposto um modelo de regressão para dados grupados utilizando a distribuição log-Burr III, que um caso particular da distribuição anteriormente citada. Os parâmetros dos modelos foram estimados utilizando os métodos de máxima verossimilhança e bootstrap. Por fim, utilizou-se um conjunto de dados reais para exemplificar a aplicação dos modelos propostos. / Interval-censored data occur when the exact survival times are known only to be in a time interval. When all individuals are evaluated in the same time intervals, causing many ties, we have grouped data. Thus, grouped survival data are particular cases of interval censored data. In this work, a regression model for grouped survival data was developed using log-beta Burr III distribution, which main characteristic is the possibility of the hazard function assuming different forms (increasing, decreasing, unimodal). Also, a regression model for grouped data was developed using log-Burr III distribution, which is a particular case of the aforementioned distribution. The parameters of the models were estimated by maximum likelihood method and bootstrap. Finally, a real data set is used to exemplify the application of the proposed models.

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Estatistica, 2016. / Submitted by Fernanda Percia França (fernandafranca@bce.unb.br) on 2016-09-19T15:39:17Z No. of bitstreams: 1 2016_AdélioHenriquedaSilvaNeto.pdf: 7022430 bytes, checksum: 482a6ceed2781b83bc70849b698e89db (MD5) / Approved for entry into archive by Raquel Viana(raquelviana@bce.unb.br) on 2016-09-19T16:16:23Z (GMT) No. of bitstreams: 1 2016_AdélioHenriquedaSilvaNeto.pdf: 7022430 bytes, checksum: 482a6ceed2781b83bc70849b698e89db (MD5) / Made available in DSpace on 2016-09-19T16:16:23Z (GMT). No. of bitstreams: 1 2016_AdélioHenriquedaSilvaNeto.pdf: 7022430 bytes, checksum: 482a6ceed2781b83bc70849b698e89db (MD5) / Na última década, diversos autores têm investigado novas famílias de distribuições de probabilidade com o intuito de obter modelos mais flexíveis para o ajuste a conjunto de dados. Neste trabalho, introduzimos pela primeira vez uma nova família de distribuições referida como a Gama tipo III Generalizada, que é uma generalização da família Gama tipo III (Torabi e Montazeri [6]). Estudamos duas distribuições particulares desta família: a Gama tipo III Burr III Generalizada (GIIIBIIIG) e a Gama tipo III Weibull Generalizada (GIIIWG). Fornecemos, também, uma descrição básica de algumas propriedades matemáticas e computacionais desta nova classe e destas novas distribuições. Para investigar o ajuste das novas distribuições foi analisado para cada modelo um conjunto de dados reais. ________________________________________________________________________________________________ ABSTRACT / In the last decade, several authors have studied new probability distribution families to obtain more flexible models. In this work, we introduce for the first time the Generalized Gama type III family of distributions wich is a generalization of gama type III family (Torabi and Montazeri [6]). We have studied two specific models of this family: Generalized Gama type III Burr III and Generalized Gama type III Weibull. We provide, also, a description of some of the mathematical and computational properties of this new class of distributions and the studied models. We fitted each model to a data set to investigate their flexibility.

Submitted by Danielle Karla Martins Silva (danielle.martins@ufpe.br) on 2015-03-12T12:39:08Z No. of bitstreams: 2 Dissertacao Luis Gustavo.pdf: 741015 bytes, checksum: 4440a3bf4f752a7b808ba89edf97abcf (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-12T12:39:08Z (GMT). No. of bitstreams: 2 Dissertacao Luis Gustavo.pdf: 741015 bytes, checksum: 4440a3bf4f752a7b808ba89edf97abcf (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2013 / Apresentamos resultados novos sobre a classe de distribuições obtidas pela composição de uma distribuição contínua qualquer com a distribuição de Harris, a qual está relacionada a um processo de ramificação. A nova classe, denominadaHarris-G, contémtodas as famílias obtidas pelo método proposto por Marshall e Olkin em 1997. Entre os resultados obtidos destacamos a decomposição da função densidade de probabilidade das novas famílias em combinação linear de densidades exponencializadas, expressões para momentos, funções geradoras, entropias e caracterização por máxima entropia. Duas novas famílias da classe Harris-G são apresentadas nesse trabalho com exemplos de aplicações práticas para motivar o uso das mesmas.

<p> Burr formation is a frequent problem in metal cutting. Burrs, which are defined as undesired projections of material resulting from plastic deformation, affect the precision of machined components and can negatively affect the assembly process. One common burr is the exit burr that forms when drilling ductile materials such as aluminum alloy. Deburring, the process of removing burrs, can account for up to 30% of the total production cost. If the burr size can be reduced, the deburring effort can also be reduced or even eliminated, resulting in an improvement in productivity and an increase in profit. </p> <p> There are different methods to reduce burr formation in drilling. One method is known as vibration assisted drilling. Vibration assisted drilling has been reported as an effective method to reduce burr height without reducing the material removal rate or permanently altering the mechanical behavior of the workpiece material. Other reported benefits of vibration assisted drilling include improvement of tool life and better machined surface quality. However, it has been reported that poor choice of vibration conditions (frequency and amplitude) can increase burr height. No accurate analytical model exists in the current literature that can predict the exit burr height for vibration assisted drilling. To predict exit burr height, a model capable of predicting thrust force accurately is important because higher thrust force produces larger exit burr. Clearly there is a need to develop these models. </p> <p> This thesis presents the development of analytical models for predicting thrust force and exit burr height for vibration assisted drilling of aluminum 6061-T6. The developed models incorporate all significant characteristics of vibration assisted drilling to achieve accurate predictions. Drilling experiments were performed over a range of cutting and vibration conditions. The experimental results demonstrate that the developed thrust force model improves the accuracy by up to 45% in comparison to the existing vibration assisted drilling models. The developed burr height model accurately predicts the exit burr height for vibration assisted drilling, with an averaged deviation of 10% from the experimental results. The developed models are also applicable to conventional drilling. Comparing with the existing drilling models, the new models improve the accuracy of thrust force and burr height predictions by 6 and 36% respectively. A fast analytical method has also been developed that predicts the favourable vibration conditions that minimize burr height. The predictions obtained using this method are consistent with the experimental results. Drilling experiments for combined frequency vibration assisted drilling were also performed over a range of vibration conditions. The experimental results demonstrate that combining two different favourable vibration conditions together produces greater mean thrust force reduction than using a single frequency vibration assistance. </p> / Thesis / Doctor of Philosophy (PhD)