The extrusion of aluminium alloys involves the shaping of the product from an homogenised billet into a complex shape. In addition the properties of the extrudate are closely related to the processing parameters (temperature, stain rate, and material morphology). Since all the parameters vary throughout the ram stroke and throughout the billet the prediction of the condition of the extrudate is complex. In this study the analysis is accomplished by the use of finite element analysis coupled with sub-illodelling of the structural features. The study is extended to include the lieat-treatment process necessary for precipitation hardened alloys subsequent to the process. The author has published these results in a number of learned journals and these are given in Appendix. After a concise introduction and crirical literature review chapter3 analyses the basic operation of the finite element package(FEM) discussing the procedures involved, the equilibrium equations and the more practical aspect of the mesh morphology and size. Finite Element analysis and material structural models have been integrated using parallel processing technology and program sub-routines. In this section the external inputs are also defined paying particular attention to the friction conditions and the constitutive equations. The thesis then proceeds to describe and analyse the integrated modelling of the process necessary to introduce the user introduction of the equations necessary to produce a comprehensive analysis of the material structural problems. This includes the cellular automata teclu-iiques. Various complex extrusion geometries are analysed and the effects of scaling considered. Development of the extrudate surface and criteria for ptedicting this important feature are coinprehebsivcly covered in chapter 5 whilst chapter 6 considers some special technologies such as the use of pockets to obtain homogenous structures. Isothermal extrusion is also included in this section.

This thesis presents the results of an investigation into the process of damage and failure in small diameter high performance synthetic fibre ropes namely Dyneema, Vectran and Technora ropes. This study was prompted by a series of fatal accidents on paragliders as a result of the line failure. All the different rope materials, including the rope with cover, without cover and the core with different number of strands, have been tensile tested. The transfer of loading and subsequent damage in different rope constituents, fibres and strands, are also discussed. The residual strength of the rope after static and cyclic preloading regimes is discussed and possible mechanisms for the damage accumulation in the rope are given. The acoustic emission monitoring of the tensile and residual strength tests shows distinctive differences between the different types of rope and permits the identification of characteristic effects of preloading on the tensile damage and failure mechanisms of all three materials. The process of damage in the Dyneema and Vectran is similar, in which damage progresses in steps during the loading history whereas Technora rope accumulates gradual increase in damage until the catastrophic failure. The application of the static preloading improves the strength of Dyneema and Vectran ropes whereas it deteriorates the mechanical properties of Technora rope. The cyclic response of Dyneema rope shows a dramatic downturn at lives in excess of 1000 cycles, but moderate cyclic loading improves the strength. The variation in surface temperature of Dyneema rope during tensile loading has been measured analysed and related to the process of damage. Dyneema fibres melt and fuse together under loading, since Dyneema is disadvantaged by its low melting temperature. Rope on rope abrasion tests, carried out on covered and uncovered Dyneema and Technora ropes, show that Dyneema rope has superior abrasion properties compared to Technora. This is due to the low compression properties of Technora, as abrasion process involves compressing the fibres. The effect of exposure to different environments, including natural weathering, -22'C, +54'C and seawater on tensile performance is discussed. The tensile properties of the Dyneema ropes are little affected by the environmental conditioning except the effect of synthetic sea water, in which case the salt crystals damage the rope fibres, once the water has evaporated.

Environmental considerations have led to the phase out of chlorofluorocarbon (CFC) refrigerants from the domestic refrigeration industry. One intriguing aspect is that the chlorine in CFCs is a good lubricating agent and any deterioration of system performance may adversely influence other environmental considerations. Based on the above, the aim of this research is to address the sustainable development of domestic refrigeration systems using the replacement refrigerant HFC-134a. The work focuses on the emissions that may arise if the electrical consumption of the product deteriorates or its durability is curtailed. Tribological characteristics on compressor components influence both of these product attributes and therefore a thorough system analysis was carried out. An in-house built experimental test rig, which monitored slight variations in the electrical power drawn by a reciprocating hermetic compressor, was used under different experimental conditions. Furthermore, a detailed life cycle assessment on a domestic refrigerator was performed to help quantify the ensuing environmental burdens. In this way, a relation between tribological characteristics, power consumption and environmental impact was studied. Results have shown that the CFC substitute will increase friction and wear characteristics on the aluminium alloy connecting rod and the steel gudgeon pin. These characteristics led to an increase in the electrical energy consumption of the compressor such that the indirect global warming implications are set to rise with HFC-134a. If the sustainable development of this product is to be ascertained then a change in refrigerants alone will not suffice. New design considerations, primarily aimed at servicing and extending the life of the hermetic compressor itself, are considered. This work helps stimulate new ideas to address environmental issues influenced by traditional engineering disciplines. For this reason additional future research work, which will help determine these implications further, is outlined.

International environmental concern led to the control and phase out of traditional chlorofluorocarbon refrigerants (CFCs) under the terms of the Montreal protocol. CFCs used in domestic applications were initially replaced with hydrofluorocarbons (HFCs) such as R134a which has a zero ozone depletion potential (ODP). The use of HFCs has also come under scrutiny as they have high global warming potential (GWP) and inferior thermodynamic and lubricating properties and have been replaced by hydrocarbon (HC) refrigerants such as R600a in much of the domestic European and Asian markets. Despite this, there has been little research into the long-term environmental consequences of their application. Domestic refrigeration compressors were analysed to ascertain the tribological contact conditions for both R600a and R134a systems. A novel pressurised micro-friction test machine was developed to simulate the tribological conditions of the critical components using aluminium on steel samples. Refrigerant charges of R600a with mineral oil (MO) and poly-ol-ester (POE) lubricant and R 134a with POE were tested for their tribological performance within the test rig. Experimental tribological information is presented from the physical test procedures to establish wear mechanisms and friction coefficients within the critical components. The tribological performance is used to predict deterioration in energy consumption and system durability. Results indicate that for higher contact stresses R600a MO charges provide a lower wear regime than R600a and R134a POE charges. At lower contact stresses the R600a and R134a POE charges provide a very low wear, very low friction regime. Despite contact conditions lead to a faster deterioration in durability, hence increase in energy consumption compared to the R600a system.

Type I diabetics need regular injections of insulin to survive. Insulin allows the cells of the body to extract glucose from the blood supply to use as fuel. Without insulin the cells turn to other backup fuel sources,this can cause side effects that are quickly fatal or gradual wasting of the bodies tissues. The use of insulin, however, is not danger free, as an incorrect dosage can quickly lead to the reduction of glucose circulating in the blood to drop to a dangerously low level. Without glucose circulating in the blood supply the brain quickly runs out of fuel causing coma and death. Because of this, a means to constantly monitor blood glucose levels has been sought for the last two decades. With such a device, diabetics could judge the correct amount of insulin to inject and be warned of low blood glucose levels. However, to date no reliable portable system has been produced. Recent developments in fibre optic biosensor technology, suggested a possible route to achieves this goal. The work in this thesis presents the development and testing of such a sensor. The sensor presented in this thesis is based around a commercial fibre optic blood gas sensor, the Paratrend 7. The oxygen-sensing element of this device was modified into a glucose sensor using polymer membranes incorporating the enzymes glucose oxidase and catalase. The research was aimed at building a glucose sensor that could be developed into a working blood glucose sensor in the minimum amount of time if the research proved successful. For this reason the Paratrend 7 sensor system was chosen to provide a clinically tested sensor core around which the glucose sensor could be built. The initial experiment, which used a Paratrend7 sensor coated in polyHEMA and glucose oxidase, produced a sensor of diameter of 700µm with a range of 0 to 4mM/1 of glucose and a 90% response time of <100 seconds in a solution with a 15% oxygen tension. The sensor design was then developed to incorporate the enzyme catalase to protect the glucose oxidase and an outer diffusion limiting polyHEMA membrane. This produced a sensor with a range of 0 to 6 mM/l and a response time of <100 seconds. The method of coating the sensors was'then improved, through a series of stages, until an optomised dip coating technique was developed. This technique produced sensors with ranges (in 7.5KPa oxygen tension solutions) between 0 to 3mM/l and 0 to lOmM/1, responsetimes of <100 seconds in some cases and with diameters of 300µm. By using a partial polyurethane outer coat the range of the sensors was increased form 0 to 4mM/l up to 0 to 24mM/1, in one case, with 90% response times in the 100to 500 second range. The sensors were then sterilised using gamma radiation and their performance before and after sterilisation examined. The gamma sterilisation was found to cause a reduction in the range of the sensors,for example 0 to 24 m /I down to 0 to 14mM/l in one case. The affect of 24 hour operation in a 5mM/1 solution of glucose and storage, for up to three months, was then investigated. Both processes were found to reduce the operational range of the sensors,0 to 20 reduced to 0 to 15 mM/i, in one case,for 24 hour operation and form 0 to 15mM/1 reduced to 0 to 11mM/1in one case for a storage time of three months. The use of the enzymes glucose oxidase and catalase together in a fibre optic as can sensor has not been previously reported in the literature as far be ascertained. The comparison of sensor performance before and after gamma sterilisation also appears to be unique as does the gamma sterilisation of a fibre optic glucose sensor.

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Upper extremity splinting is a popular treatment method for a range of conditions, such as rheumatoid arthritis. The intent of this treatment approach is multifaceted, but fundamentally, the provision of tools to enable and encourage patients to carry out everyday activities and to improve their quality of life is paramount. However, the aesthetic and functional limitations of wrist immobilisation splints demonstrate various weaknesses in terms of wear duration and frequency. Patient compliance is often compromised due to a number of factors, including the perceived stigma associated with assistive devices. Additive Manufacturing (AM) has proved its worth in a number of applications relating to the design of assistive devices; builds of complex, bespoke fitting geometries make AM an ideal fabrication method for upper extremity splints. However, recent advances in system technology to enable multi-material builds have been limited in this field, and a distinct need for a specialised three-dimensional (3D) Computer Aided Design (CAD) software approach is required to allow therapists to design splints for AM. Furthermore, the intent to keep practising therapists at the forefront of splint prescription is of utmost importance. This research proposes a digitised splinting approach, specifically through development of a 3D CAD software strategy to allow therapists to capture their design intent without compromising creativity. Furthermore, the approach proposes the exploration of AM build capabilities by allowing the integration of more creative features, such as aesthetically pleasing lattice structures for increased skin ventilation. The approach also proposes the integration of multiple materials to replicate and improve upon current splint design and fabrication practises. The approach therefore explores an exciting new paradigm for upper extremity splinting, the driving characteristics of which have not been proposed before as a collective medium. This research describes the feasibility of capturing therapists design intent in a 3D CAD virtual environment, whilst capturing therapists opinions of the approach with suggestions for future research and development. Results concluded that therapists were excited by the proposed transition in AM splinting, but that significant development is required elsewhere to establish a supporting infrastructure in order to make the approach a viable option in future upper extremity splinting.

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In der Dissertation erfolgt die methodische Einbindung von Wirtschaftlichkeitsaspekten und Gestaltungsempfehlungen für das selektive Elektronenstrahlschmelzen (SEBM) mit der Titanlegierung Ti6Al4V in den Konstruktionsprozess. Hierzu werden Werkzeuge und Methoden erarbeitet um die Wirtschaftlichkeit des EBM-Prozesses anhand bestimmter Entwurfsparameter aus dem Produktentwicklungsprozess zu bewerten, ohne eine konkrete, additive Gestalt entwickeln zu müssen. Zudem werden anhand verschiedener Demonstratoren die Fertigungsgrenzen des Verfahrens speziell an der Titanlegierung Ti6Al4V erprobt. Infolge dessen erfolgt die Eingliederung des EBM Verfahrens in die Allgemein- und Grundtoleranzen sowie die Erarbeitung eines von Gestaltungsempfehlungen und eines umfassenden Konstruktionskataloges. Anhand von 3 Leichtbauanwendungen ist abschließend das Potenzial des EBM in Verbindung mit der Topologie- bzw. Strukturoptimierung dargestellt worden.:Abkürzungsverzeichnis Symbolverzeichnis 1 Einleitung 1.1 Motivation 1.2 Aufbau der Arbeit 2 Stand der Technik 2.1 Begrifflichkeiten und Normung der additiven Fertigung 2.2 Das selektive Elektronenstrahlschmelzen 2.2.1 Prozessbeschreibung 2.2.2 Einflussfaktoren auf die Bauteilfertigung beim EBM 2.2.3 Nachbearbeitung 2.3 Produktgestaltung im Kontext der additiven Fertigung 2.3.1 Potenziale bei der additiven Produktgestaltung für EBM 2.3.2 Leichtbau in der Produktentwicklung 2.3.3 Strukturoptimierung in Verbindung mit der additiven Fertigung 2.3.4 Modelldatenerzeugung und deren Umwandlung 2.4 Design for Additive Manufacturing 2.4.1 Gestaltungsregeln der pulverbettbasierten additiven Fertigung 2.4.2 Gestaltungsrichtlinien für EBM 2.4.3 Maß-, Form- und Lagetoleranzen 2.5 Potenzialbewertung und Kostenabschätzung 2.5.1 Potenzialbewertung der additiven Fertigung 2.5.2 Kostenkalkulation 2.6 Zusammenfassung zum Stand der Technik 3 Methode zur Bewertung des EBM als potenzielles Fertigungsverfahren 3.1 Potenzialabschätzung für das EBM 3.1.1 Verfahrenspotenziale des EBM 3.1.2 Verfahrenspotenzialbewertung des Anwenders 3.1.3 Randbedingungen aus dem Produktentwicklungsprozess 3.1.4 Berechnungen des Potenzials 3.1.5 Ergebnis, Handlungsempfehlungen und Validierung 3.2 Bewertung der Wirtschaftlichkeit des EBM 3.2.1 Bauzyklus- und Bauteilherstellungskosten 3.2.2 Ermittlung der maximalen Bauteilanzahl pro Bauzyklus 3.2.3 Material- und Fertigungskosten 4 Erarbeitung geometrischer Grenzen des EBM 4.1 Geltungsbereich der Gestaltungsempfehlungen 4.1.1 Ausgangswerkstoff 4.1.2 Anlagen- und Prozessparameter 4.2 Mess- und Auswertestrategien 4.3 Allgemeine Verfahrensgenauigkeit innerhalb der Anlage 4.3.1 Abweichungen innerhalb des Bauraums der Anlage A2X 4.3.2 Abweichungen innerhalb des Bauraums der Anlage Q20plus 4.3.3 Zwischenfazit 4.4 Minimal mögliche Strukturen beim EBM 4.4.1 Minimaler Zylinderdurchmesser mit Achswinkel 90° zur Bauebene 4.4.2 Minimaler Zylinderdurchmesser mit Achswinkel 45° zur Bauebene 4.4.3 Minimaler Zylinderdurchmesser mit Achswinkel 0° zur Bauebene 4.4.4 Minimaler Bohrungsdurchmesser mit Achswinkel 90° zur Bauebene 4.4.5 Minimaler Bohrungsdurchmesser mit Achswinkel 0° zur Bauebene 4.4.6 Minimale Wandstärke in Baurichtung 4.4.7 Minimaler Spaltabstand in Baurichtung 4.4.8 Winkeltreue an Downskin-Flächen 4.4.9 Minimale Wandstärke überhängender Strukturen 4.4.10 Zwischenfazit und -diskussion 4.5 Pulverentfernung 4.5.1 Versuchsauswertung zur Pulverentfernung 4.5.2 Maßhaltigkeit der Rohröffnungen des Demonstrators 4.6 Überhanguntersuchungen 4.6.1 Kritischer Überhangwinkel 4.6.2 Kritische freitragende Überhanglänge 4.6.3 Zwischenfazit und Diskussion 4.7 Einfluss der Stützstruktur auf die Bauteilqualität 4.8 Minimalmaß lasttragender Strukturen 4.8.1 Festigkeit schmaler Strukturen 4.8.2 Zwischenfazit und Diskussion 4.9 Gestaltungsempfehlungen für EBM 4.9.1 Geometrische Genauigkeit und Allgemeintoleranz des EBM 4.9.2 Konstruktionskatalog für das EBM 4.9.3 Diskussion und Implikation der Ergebnisse 5 Angewandte Strukturoptimierung 5.1 Main Gear Bracket (MGB) 5.1.1 Auslegungsgrundlagen 5.1.2 Strukturoptimierungsprozess 5.1.3 Festigkeitsnachweise 5.1.4 Fertigung 5.2 Formula Student Lenkstockhalter (FSL) 5.3 Flight Crew Rest Compartment Bracket (FCRC) 5.4 Zusammenfassung zur Strukturoptimierung 5.5 Beispielhafte Umsetzung der Kostenabschätzung 6 Zusammenfassung der Arbeit 7 Ausblick 8 Literaturverzeichnis 9 Abbildungsverzeichnis 10 Tabellenverzeichnis Anlagen / In this dissertation the methodical integration of economic aspects and design recommendations for selective electron beam melting (SEBM) with the titanium alloy Ti6Al4V into the design process is carried out. For this purpose, tools and methods are developed to evaluate the economic efficiency of the EBM process on the basis of certain design parameters from the product development process, without having to develop a concrete, additive design. In addition, the manufacturing limits of the process are tested using various demonstrators, especially on the titanium alloy Ti6Al4V. As a result, the EBM process is integrated into the general and basic tolerances and a design recommendation and a comprehensive design catalogue are developed. Finally, the potential of EBM in connection with topology and structural optimisation was demonstrated on the basis of 3 lightweight construction applications.:Abkürzungsverzeichnis Symbolverzeichnis 1 Einleitung 1.1 Motivation 1.2 Aufbau der Arbeit 2 Stand der Technik 2.1 Begrifflichkeiten und Normung der additiven Fertigung 2.2 Das selektive Elektronenstrahlschmelzen 2.2.1 Prozessbeschreibung 2.2.2 Einflussfaktoren auf die Bauteilfertigung beim EBM 2.2.3 Nachbearbeitung 2.3 Produktgestaltung im Kontext der additiven Fertigung 2.3.1 Potenziale bei der additiven Produktgestaltung für EBM 2.3.2 Leichtbau in der Produktentwicklung 2.3.3 Strukturoptimierung in Verbindung mit der additiven Fertigung 2.3.4 Modelldatenerzeugung und deren Umwandlung 2.4 Design for Additive Manufacturing 2.4.1 Gestaltungsregeln der pulverbettbasierten additiven Fertigung 2.4.2 Gestaltungsrichtlinien für EBM 2.4.3 Maß-, Form- und Lagetoleranzen 2.5 Potenzialbewertung und Kostenabschätzung 2.5.1 Potenzialbewertung der additiven Fertigung 2.5.2 Kostenkalkulation 2.6 Zusammenfassung zum Stand der Technik 3 Methode zur Bewertung des EBM als potenzielles Fertigungsverfahren 3.1 Potenzialabschätzung für das EBM 3.1.1 Verfahrenspotenziale des EBM 3.1.2 Verfahrenspotenzialbewertung des Anwenders 3.1.3 Randbedingungen aus dem Produktentwicklungsprozess 3.1.4 Berechnungen des Potenzials 3.1.5 Ergebnis, Handlungsempfehlungen und Validierung 3.2 Bewertung der Wirtschaftlichkeit des EBM 3.2.1 Bauzyklus- und Bauteilherstellungskosten 3.2.2 Ermittlung der maximalen Bauteilanzahl pro Bauzyklus 3.2.3 Material- und Fertigungskosten 4 Erarbeitung geometrischer Grenzen des EBM 4.1 Geltungsbereich der Gestaltungsempfehlungen 4.1.1 Ausgangswerkstoff 4.1.2 Anlagen- und Prozessparameter 4.2 Mess- und Auswertestrategien 4.3 Allgemeine Verfahrensgenauigkeit innerhalb der Anlage 4.3.1 Abweichungen innerhalb des Bauraums der Anlage A2X 4.3.2 Abweichungen innerhalb des Bauraums der Anlage Q20plus 4.3.3 Zwischenfazit 4.4 Minimal mögliche Strukturen beim EBM 4.4.1 Minimaler Zylinderdurchmesser mit Achswinkel 90° zur Bauebene 4.4.2 Minimaler Zylinderdurchmesser mit Achswinkel 45° zur Bauebene 4.4.3 Minimaler Zylinderdurchmesser mit Achswinkel 0° zur Bauebene 4.4.4 Minimaler Bohrungsdurchmesser mit Achswinkel 90° zur Bauebene 4.4.5 Minimaler Bohrungsdurchmesser mit Achswinkel 0° zur Bauebene 4.4.6 Minimale Wandstärke in Baurichtung 4.4.7 Minimaler Spaltabstand in Baurichtung 4.4.8 Winkeltreue an Downskin-Flächen 4.4.9 Minimale Wandstärke überhängender Strukturen 4.4.10 Zwischenfazit und -diskussion 4.5 Pulverentfernung 4.5.1 Versuchsauswertung zur Pulverentfernung 4.5.2 Maßhaltigkeit der Rohröffnungen des Demonstrators 4.6 Überhanguntersuchungen 4.6.1 Kritischer Überhangwinkel 4.6.2 Kritische freitragende Überhanglänge 4.6.3 Zwischenfazit und Diskussion 4.7 Einfluss der Stützstruktur auf die Bauteilqualität 4.8 Minimalmaß lasttragender Strukturen 4.8.1 Festigkeit schmaler Strukturen 4.8.2 Zwischenfazit und Diskussion 4.9 Gestaltungsempfehlungen für EBM 4.9.1 Geometrische Genauigkeit und Allgemeintoleranz des EBM 4.9.2 Konstruktionskatalog für das EBM 4.9.3 Diskussion und Implikation der Ergebnisse 5 Angewandte Strukturoptimierung 5.1 Main Gear Bracket (MGB) 5.1.1 Auslegungsgrundlagen 5.1.2 Strukturoptimierungsprozess 5.1.3 Festigkeitsnachweise 5.1.4 Fertigung 5.2 Formula Student Lenkstockhalter (FSL) 5.3 Flight Crew Rest Compartment Bracket (FCRC) 5.4 Zusammenfassung zur Strukturoptimierung 5.5 Beispielhafte Umsetzung der Kostenabschätzung 6 Zusammenfassung der Arbeit 7 Ausblick 8 Literaturverzeichnis 9 Abbildungsverzeichnis 10 Tabellenverzeichnis Anlagen

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