published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Paul Dudley Hartung. / M.S.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / by Peter Thompson. / B.S.

After the review of the basic theory of the inverse method, a new modified arc-length search method is proposed to find better initial solution. The methods to deal with the vertical walls are also discussed and presented. Then, a generalized multi-step inverse FEM method is proposed. It solves two key obstacles: the first one is to determine the initial solution of the intermediate three-dimensional configurations and the other is to control the movement of nodes so they could only slide on constraint surfaces during the search by Newton-Raphson iteration. The computer implementation of the generalized multi-step inverse FEM is also presented. By comparing to the simulation results using a commercial software system, the effectiveness of the new method is validated. / Currently, there are a number of commercial FEM software systems available in the market. These software systems are based on an incremental FEM process that models the sheet metal stamping process in small incremental steps. Even though the incremental FEM is accurate, it is not suitable for the initial conceptual design for its needing of detailed design parameters and enormous calculation times. As a result, another type of FEM, called the inverse FEM method or one-step FEM method, has been proposed. While it is less accurate than that of the incremental method, this method requires much less computation and hence, has a great potential. However, it also faces a number of unsolved problems, which limits its application. This motivates the presented research. / From a physical point of view, the formability and the quality of a product are influenced by several factors. The design of the product in the initial stage and the motion of the press during the production stage are two of these crucial factors. This thesis focuses on the numerical simulation for these two factors using FEM. / Other than the product design, the punch motion (including punch speed and punch trajectory) of the stamping press also has significant effect on the formability and the quality of the product. In fact, this is one of the major reasons why hydraulic presses and/or servo presses are used for parts which demand high quality. In order to reveal the quantitative correlation between the punch motion and the part quality, the Cowper-Symonds strain rate constitutive model and the implicit dynamic incremental FEM are combined to conduct the research. The effects of the punch motion on the part quality, especially the plastic strain distribution and the potential springback, have been investigated for the deep drawing and the bending processes respectively. A qualitative relationship between the punch motion and the part quality is also derived. / The reaction force of the punch motion causes the dynamic deformation of the press during the stamping, which in turn influences the part quality as well. This dynamic information, in the form of the strain signal, is an important basis for the on-line monitoring of the part quality. By using the actual force as the input to the press, the incremental FEM is needed to predict the strain of the press. The result is validated by means of experiments and can be used to assist the on-line monitoring. / The sheet metal stamping process plays an important role in modern industry. With the ever-increasing demand for shape complexity, product quality and new materials, the traditional trial and error method for setting up a sheet metal stamping process is no longer efficient. As a result, the Finite Element Modeling (FEM) method has now been widely used. / Huang Ying. / "March 2006." / Adviser: Ruxu Du. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6694. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 141-160). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Thesis. 1979. M.C.P.--Massachusetts Institute of Technology. Dept. of Urban Studies and Planning. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Bibliography: leaves 188-190. / M.C.P.

Orientador: Marcos Valério Ribeiro / Banca: José Vitor Candido de Souza / Banca: Manoel Cleber de Sampaio Alves / Banca: Rosemar Batista da Silva / Banca: João Roberto Ferreira / Resumo: Reduzir o uso de fluidos de corte em operações de usinagem é uma meta que tem sido buscada na indústria devido aos problemas ecológicos e de saúde humana, causados pelos fluidos de corte. No entanto, os fluidos de corte ainda promovem uma vida de ferramenta mais longa para muitas operações de usinagem. Este é o caso da operação de fresamento de acabamento da liga de titânio Ti6Al4V usando pastilhas de metal duro recobertas. Portanto, o objetivo deste trabalho é estudar condições de corte mais adequadas para o uso da técnica de mínima quantidade de fluido, ou seja, condições que tornem a vida da ferramenta na técnica MQF, mais próximas ou superiores àquelas obtidas com corte sem lubri-refrigeração e corte com jorro de fluido, sem prejudicar a rugosidade da peça. Para alcançar estes objetivos vários experimentos de fresamento de acabamento foram realizados, variando-se a velocidade de corte e taxa de avanço com aplicação da técnica MQF com o uso de três diferentes fluidos comparados com o corte sem lubri-refrigeração e corte com jorro de fluido. A principal conclusão deste estudo foi que a aplicação da técnica MQF no processo de fresamento de acabamento do Ti-6Al-4V aumenta a vida da ferramenta, melhorando a produtividade e rugosidade, quando mantidas as mesmas condições de corte originalmente propostas / Abstract: To reduce cutting fluids use in machining operations is one goal that has been searched in industrial companies, due to ecological and human health problems caused by the cutting fluid. However, the cutting fluids still provide a longer tool life for many machining operations. This is the case of Ti6Al4V titanium alloy end milling operation using coated carbide inserts. Therefore, this work objective is to study cutting conditions more suitable for minimum quantity of fluid technique use, i.e., conditions which make tool life in MQF technique, closer or over to that obtained with dry cutting and cutting with fluid fload, without damaging the workpiece roughness. To reach these goals several end milling experiments were carried out, varying up cutting speed and feed rate with MQF technique application with three different fluids compared with dry cutting and cutting with fluid fload. The main study conclusion was that applying the MQF technique in Ti-6Al-4V end milling process increases tool life, improving productivity and roughness, when kept up the same cutting conditions proposed originally / Doutor

Spindle failure during fast steel rolling is one of the major equipment failures encountered at Onesteel Whyalla Steelworks (WS). Spindle failure whilst infrequent has been occurring over a long period of time and is a significant cost impost in terms of replacement parts, repair and lost production. Previous attempts at mechanical analysis and spindle redesign have not rectified the problem. This thesis presents an in-depth investigation of the problem and uses a completely new approach, modeling and control, to obtain a solution to the problem.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 130-135).

The proliferation of electric machines has drastically increased in recent years and is likely to increase into the future. This interest in the production of advanced, high power density electrical machines that are small in size has heightened the need for flexible manufacturing processes to produce their laminated components during short batch and prototyping production runs. A means of cost effective, accelerated prototyping of these machines will have a substantial impact on their design and optimization, reducing time requirements to produce and test a given design. A review of the current manufacturing methods for prototyping electric machines was conducted. In particular, laser cutting, electric discharge machining, and abrasive waterjet (AWJ) machining were researched as competitive processes. Each of these methods exhibits marked advantages and disadvantages that present the opportunity for a new process to compete. This work investigates the applicability of high throughput profile milling (HTPM) for the prototyping of advanced electric machines, specifically, the process parameter space for milling of electrical steels. The material response will be determined by characterizing its specific cutting energy and utilizing this to develop a model to predict cutting forces during the milling process. Optimal process parameters will be investigated to obtain maximum productivity and minimal burr formation. Finally, the impact of HTPM processing on the magnetic properties of electrical steels will be compared to that of a leading prototyping technology, AWJ machining.

Slight revision of Thesis (doctoral), Bonn, 1977. / Includes bibliographical references and indexes.