Linear Machines for Long Stroke Applications: a review

This document reviews the current state of the art in the linear machine technology. First,the recent advancements in linear induction, switched reluctance and permanent magnet machines arepresented. The ladder slit secondary configuration is identified as an interesting configuration for linearinduction machines. In the case of switched reluctance machines, the mutually-coupled configuration hasbeen found to equate the thrust capability of conventional permanent magnet machines. The capabilities ofthe so called linear primary permanent magnet, viz. switched-flux, flux-reversal, doubly-salient and verniermachines are presented afterwards. A guide of different options to enhance several characteristics of linearmachines is also listed. A qualitative comparison of the capabilities of linear primary permanent magnetmachines is given later, where linear vernier and switched-flux machines are identified as the most interestingconfigurations for long stroke applications. In order to demonstrate the validity of the presented comparison,three machines are selected from the literature, and their capabilities are compared under the same conditionsto a conventional linear permanent magnet machine. It is found that the flux-reversal machines suffer froma very poor power factor, whereas the thrust capability of both vernier and switched-flux machines isconfirmed. However, the overload capability of these machines is found to be substantially lower than theone from the conventional machine. Finally, some different research topics are identified and suggested foreach type of machine

Disc-geometry reluctance motors

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Optimisation of high-speed automated layup of thermoset carbon-fibre preimpregnates

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Infrastructure Design, Signalling and Security in Railway

Railway transportation has become one of the main technological advances of our society. Since the first railway used to carry coal from a mine in Shropshire (England, 1600), a lot of efforts have been made to improve this transportation concept. One of its milestones was the invention and development of the steam locomotive, but commercial rail travels became practical two hundred years later. From these first attempts, railway infrastructures, signalling and security have evolved and become more complex than those performed in its earlier stages. This book will provide readers a comprehensive technical guide, covering these topics and presenting a brief overview of selected railway systems in the world. The objective of the book is to serve as a valuable reference for students, educators, scientists, faculty members, researchers, and engineers

Automated Fibre Placement with In-Situ Ultraviolet Curing and On-The-Fly Resin Impregnation

Vehicle emissions contribute to up to one third of the world's air pollution [1]. Reducing vehicle weight is crucial to reducing these emissions. Composite materials offer high specific strength-to-weight ratios which make them ideal for lightweight applications; however, existing composite manufacturing is slow and expensive. Automated Fibre Placement (AFP) is a state-of-the-art composite manufacturing process but is limited by the low complexity of parts it can produce; the cost, size and speed of the actuation systems; expensive and sensitive material options; and numerous pre and post-processes required in order to complete a part. This research proposes a new and efficient composite manufacturing process that addresses these limitations by combining AFP technology with in-situ ultraviolet (UV) curing and on-the-fly fibre and resin impregnation (UVAFP). The body of this thesis focused on proving the process concept and building robust predictive models for the technology. It was proposed that reducing the size of the placement head would increase the capability of this technique to manufacture more complex parts. It was shown that by optimising the placement head clearance angle, placement head width and the compaction roller radius the minimum placement radius and arc length could be as small as 100mm and 90 degrees respectively. It was also demonstrated that industrial robots were sufficiently accurate and repeatable to act as placement articulators for AFP. The feed rate, path interpolation point filtering and spindle speed were optimised to achieve a path following accuracy of less than 0.042mm. By increasing the tension in the tow and compaction force, dry fibre tows were shown to be a suitably dimensionally stable replacement for expensive towpregs with minimal gaps and overlaps. Dry glass fibre tows and bulk vinylester resin impregnated on-the-fly was chosen as an inexpensive and versatile material system and consolidation approach for use in UVAFP. The material system was shown to have comparable mechanical properties to aluminium and steel but lighter with equivalent properties to composites manufactured by traditional techniques. Rapid impregnation times were demonstrated up to 2160 mm/sec. High intensity UV light curing eliminated the need for post process curing and shortened the cure time and increased layup speeds. When the UV light was applied in a ply-by-ply in-situ approach, the cure time was measured to decrease the current thermal cure cycle length by 43.75% and the degree-of-cure was increased by 1.3% (as measured indirectly by the interlaminar shear strength). By characterising the process parameters the effect on degree of cure and degradation could be controlled and predicted. A degree of cure in excess of 99% was achieved, providing equivalent material properties to traditional thermal cured composites while minimising peak exposure temperatures, thus reducing mass loss caused by thermo-oxidative degradation. UVAFP was demonstrated to be a viable composite manufacturing process capable of producing high quality components and addressing the limitations of current AFP systems. The technology was shown to address efficiency shortfalls and make composite manufacturing economical and accessible to vehicle manufacturers searching for manufacturing process solutions for lightweight