Good welding research requires accurate control of the variables involved,to achieve consistent results. The variables involved in arc welding are of the dependent and independent type. Control of the independent variables such as arc current, arc voltage and welding velocity is necessary to control the independent variables such as penetration, electrode consumption rate, etc. The purpose of this thesis was to design, develop and test an automatic welding machine which controlled the above variables within the limits required for welding research.

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A major challenge in tire research, is tire wear modeling. There are too many factors affecting tire wear, and part of those factors are difficult to be accurately expressed in physics and math. The objective of this research is to develop a machine learning based rubber sample wear model, and find the correlation between sample wear and tire wear. To develop this model, accurate and diverse wear data is necessary. The Dynamic Friction Tester (DFT) was designed and built for this purpose. This test machine has made it possible to collect accurate rubber sample wear data which has been validated under different conditions. Wear tests under diverse test conditions were conducted, and the test data were used to train machine learned based wear models with different algorithms, such as Neural Networks and Support Vector Machines. With test-proved wear behavior classification as additional input, and feature selection, performance of the trained rubber sample wear model has been further improved. To correlate rubber sample wear and tire wear, a set of correlation functions were developed and proposed. By validating the correlation functions using tire wear test data collected on roads, this research contributes a fast and economical approach to predict tire wear. / Doctor of Philosophy / Tire wear is closely related to the life time of tire, and excessive wear of tire can results in serious accidents. Since 1950s, research have been done to predict tire wear using experiments and empirical relations. These approaches are expensive, time consuming, and highly restricted to certain conditions. The objectives of this research is to develop a statistic based rubber sample wear model, and find the correlation between rubber sample wear and tire wear. To develop the statistic based rubber sample wear model, a test machine, named Dynamic Friction Tester (DFT) was designed and built to collect rubber sample wear data. The final rubber sample wear model is trained by wear data under 600 different test conditions. A set of mathematical equations were proposed to correlate rubber sample wear and tire wear. These equations were validated by actual tire wear data collected from lab and public roads. In combination of the statistic based rubber sample wear model and mathematical relation between rubber sample wear and tire wear, this research contributes a flexible, economical, and fast method to predict tire wear.

Thesis (MScIng)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Lomolding is a new process similar to injection moulding. In this thesis a numerical model of the polymer flow into the cavity is presented. The model is used to compare the two processes with each other. Lomolding and injection moulding were modelled numerically with the finite element method. The model was an axisymmetric model and takes phenomena such as generalised Newtonian flow, free surfaces, moving boundaries and solidification into account. The processes’ characteristics that were compared are the cavity pressure, shear rate and shear stress. Improvements in these characteristics will result in lomolding having smaller machines, less fibre breakage and a better potential for in-mould-decoration. The thesis shows that lomolding has substantially lower shear rates and shear stresses than injection moulding. The model was also used to investigate certain machine design aspects, and to gain a better understanding of the polymer flow in lomolding. / AFRIKAANSE OPSOMMING: Lomoldering is ’n nuwe proses soortgelyk aan inspuitgiet. Hierdie tesis beskou ’n numeriese model van die polimeervloei soos dit in die gietholte invloei. Die model word gebruik om die twee prosesse met mekaar te vergelyk. Lomoldering en inspuitgiet is numeries gemodeleer met die eindige-elementmetode. Die model is aksiaal-simmetries en neem verskynsels soos Newtoniese vloei, vrye oppervlakke, bewegende grense en stolling in ag. Die proses-karakteristieke wat vergelyk is, sluit die gietholtedruk, vervormingstempo en skuifspanning in. Verbeterings in hierdie karakteristieke sal meebring dat lomoldering kleiner masjiene nodig sal hê, minder veselskade sal veroorsaak en meer versoenbaar met in-gietholte-versierings sal wees, vergeleke met inspuitgiet. Die tesis toon dat lomoldering laer vervormingstempo’s en skuifspanning het, in vergelyking met inspuitgiet. Die model is ook gebruik om sekere masjienontwerpaspekte te ondersoek, en om die polimeervloei in lomoldering beter te verstaan.

Len Lye was born in Christchurch, New Zealand, in 1901. Lye was an avid enthusiast of kinetic sculpture and experimental film. In 1965 Lye built a prototype for a kinetic sculpture called Blade that he intended would be a much larger work. In 1996, Dr. Shayne Gooch of the University of Canterbury embarked on a research contract that saw the fruition of Lye’s Blade at a scale previously unachieved. This work was given the name Big Blade. This thesis provides a study into the maximum realisable scale of Blade using technology and materials available today. A new pivoting clamp design is tested and assessed using a small scale Blade sculpture built at the University of Canterbury and used as a test rig. Advancements in technology, material availability and manufacturing techniques lead to a comprehensive fatigue study of the new clamp design. Stresses are measured at the critical stress location in the blade material and a new maximum economic scale of Blade is suggested. The new sculpture requires a blade material that measures 10024mm x 1080mm x 22mm. The visible blade length is 8424mm. The new sculpture is called Giant Blade. A critical aesthetic component for Len Lye’s performance of Blade is the mode shapes formed by the blade material. Specifically, the second and third bending modes (Lye’s single and double harmonic) and the first torsional bending mode (Lye’s shimmering frequency). These frequencies are calculated using the new pivoting clamp design to ensure that these sections of the performance are maintained in Giant Blade. An important requirement of the new sculpture drive mechanism is the capability to reduce the amplitude of shuttle oscillation dynamically during Blade performances. This capability allows bending stresses in the blade material to be reduced in the third bending mode of vibration without halting the performance to adjust the shuttle oscillation amplitude. Four dynamically adjustable variable stroke mechanisms are presented and compared using the methods of Pahl and Beitz. A suitable mechanism for Giant Blade is selected and a proposed arrangement for the new sculpture is provided. An embodiment design is presented for Giant Blade. This embodiment design consists of a new pivoting clamp design and the proposed variable stroke mechanism. Further work includes the design of a mechanism to support the ball and wand assembly.

This Master Thesis was performed within Research & Technology at GKN Aerospace, Trollhättan. GKN Aerospace is participating in the Clean Sky 2 program, delivering the ICC to the UltraFan demonstrator. On this demonstrator, the split and load paths of three components in the compressor module are similar to earlier engine configurations, but GKN wanted to investigate if there are other, more efficient ways of building this structure. The aim of this thesis was therefore to investigate if there is a more efficient architecture and design of the static components in the compressor module for the UltraFan engine. Utilizing a more efficient architecture and design GKN can, in exchange of undertaking a larger part of the engine, provide engine manufacturers a more lightweight solution. This goes accordingly with GKN’s aim to undertake a larger total share of aero engines. The approach for concept development during this thesis has been based on a five-step concept generation method. First knowledge about different engine architectures and component designs was gathered through qualitative interviews with experts. This was followed by the creating of a simplified baseline, or reference, model based on the UltraFan compressor module. A Finite Element Analysis, FEA, of the baseline was performed which generated further understanding about the current design. The knowledge gathered, both in the interviews and by evaluating the baseline, was used as a basis when generating concepts. Four concepts were evaluated using a screening matrix, where the concept that best satisfied the set requirements was further developed. The refined concept was then compared to the baseline, by analyzing stiffness and ovalization for both designs. The results from the concept evaluation indicated that possible weight savings can be made, but further investigation and refinements are required to ensure fulfillment of the set stiffness and deformation requirements. A further refined version of the baseline simulation model and associated methods could be used to evaluate how different designs affect the performance in terms of weight, stiffness and ovalization.

"In this work a new graphically driven interactive stress reanalysis finite element technique has been developed so that an engineer can easily carry out manual geometric changes in a machine element during the early design stage. The interface allow an engineer to model a machine element in the commercial finite element code ANSYS® and then modify part geometry graphically to see instantaneous graphical changes in the stress and displacement contour plots. A reanalysis technique is used to enhance the computational performance for solving the modified problem; with the aim of obtaining results of acceptable accuracy in as short a period of time in order to emphasize the interactive nature of the design process. Three case studies are considered to demonstrate the effectiveness of the prototype graphically driven reanalysis finite element technique. The finite element type considered is a plane stress four-node quadrilateral based on a homogenous, isotropic, linear elastic material. The first two problems consider a plate with hole and plate with fillets. These two examples demonstrate that by changing the hole and fillet size/shape, an engineer can manually obtain an optimum design based on the stress concentration factor, i.e. engineer-driven optimization process. Each case study considered multiple redesigns. A combined approximation reanalysis method is used to solve each redesigned problem. The third case study considers a support bracket. The goal is to design the cantilever portion of the bracket to have uniform strength and to minimize the stress concentration at the fillet. The major beneficiaries of the work will be engineers working in product development and validation of components and structures, which are subjected to mechanical loads. The scientific and technological relevance of this work applies not only to the early stage of design, but to a number of other applications areas in which benefits may accrue. A company may have needs for a rapid analysis and re-analysis tool for fatigue assessment of components manufactured slightly out of tolerance. Typically this needs to be carried out under a very restrictive time scale."

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaf 89. / by Bruce Alan Olsen. / M.S.

A seleção de componentes mecânicos não é uma tarefa fácil e exige um substancial know-how e experiência. As ferramentas atuais trabalham de forma isolada umas das outras, além disto não levam em consideração os requisitos que a interface de um componente exige do outro onde se acoplará, e por consequência os custos de fabricação e logísticos envolvidos para a compatibilização das interfaces. Para auxiliar neste processo está sendo proposto um método para desenvolver um SE (Sistema Especialista) para a seleção de componentes mecânicos que além de levar em conta os requisitos de aplicação, também considera no processo de seleção as deficiências supracitadas. Outro aspecto é que, leva em conta as diretrizes do projeto e os recursos de fabricação da planta, e em paralelo ao processo de seleção também pode dimensionar os componentes selecionados e as interfaces das peças nas quais se acoplarão. O processo de aquisição do conhecimento é uma das principais etapas de desenvolvimento de um SE é considerado como um dos estágios mais importantes em sua execução. Em função disto está sendo proposto um método alternativo que permite que o conhecimento seja adquirido de forma sistemática e organizada pelo engenheiro do conhecimento e pelo especialista para o seu emprego na construção da base de dados do SE. O SE desenvolvido com base no método de aquisição de conhecimento proposto neste trabalho é validado através de dois casos exemplo, inseridos em um projeto de uma máquina de processamento de papel. A validação se dá através da análise de especialistas quanto à adequação dos componentes selecionados pelo SE, comparando-os com o projeto atual. Como resultado, observa-se uma substancial redução dos custos de projeto em função dos componentes selecionados, além da economia no tempo gasto pelos projetistas neste processo de seleção. / Selecting mechanical components is not an easy task and requires a substantial amount of knowledge and experience. The current component selecting tools do not work in an integrated manner, not taking into account component interface requirements for coupling it to another component and, consequently, not considering manufacturing and logistic costs for the interfaces compatibility. In order to improve this process, this thesis proposes a method for the development of an ES (Expert System) for mechanical components selection, which considers both application and component interface requirements. Additionally, the ES will also take into consideration design guidelines and the manufacturing plant capabilities, so it will also be able to scale the selected components and its interfaces. The process of knowledge acquisition is one of the main stages of the ES development and is considered as one of the most important stages in its execution. As a result of this, an alternative method is proposed that allows the knowledge to be acquired in a systematic and organized way by the knowledge engineer and the specialist for its use in the construction of the ES database. The ES developed based on the proposed knowledge acquisition method is validated through two case studies in a paper processing machine design. The validation is done through the analysis of experts regarding the suitability of the components selected by the ES, comparing them with the current project. As a result, there is a substantial reduction in design costs due to the selected components, as well as the savings in the time spent by the designers in this selection process.

Thesis (M.S.)--Brigham Young University, Department of Mechanical Engineering, 2004. / Includes bibliographical references (p. 259-261).