Conceptual design synthesis is part of the conceptual phase of the design process, which focuses on creating alternative, candidate solutions. Conceptual design phase has the greatest influence on the cost and characteristics of the final product; an excellent detailed design based on a poor and inappropriate concept can never compensate for the inadequacy of the concept. Conceptual design is difficult, which currently relies on the designer’s intuition and experience to guide the process. A major issue in conceptual design is that often not many alternative candidate solutions are explored by the designer during the design process. The major reasons for this are the tendency to delimit a design problem area too narrowly and thus not being able to diversify the possible set of design solutions, possible bias towards a limited set of ideas, and time constraints. Many researchers recommended a thorough search of the design space for developing a good solution; this requires generation of a large solution space. Mechanical devices (mechanisms and machines) have fascinated the mankind throughout recorded history. Conceptual design synthesis of mechanical devices is difficult even for humans, and is also difficult to completely automate. In a single state design task, the relation between an input and output are fixed, but in a multiple state design task, the relation is not fixed. Much of the current research has been focused on supporting synthesis of single state devices, in particular where the device has to convert an input motion into an output motion. Synthesis of multiple state device is in contrast rather poorly understood and supported. Complete automation is unlikely to be possible; developing support taking into account the strength of computer and and human is important mechanical device is not adequate the biggest source for understanding of this process, and for its subsequent support, is human designers. The concept of state for a mechanical device is explained in detail by analyzing the existing multiple state mechanical devices. An operating state described by elemental functions (defined by efforts- motions of input and output components) and their associated Understanding and Supporting Conceptual Design Synthesis of Multiple State Mechanical Devices configurations and configuration changes. However, study of current literature indicates that little has been known about the actual processes carried out by designers in synthesizing multiple state devices. The main objectives of this thesis, therefore, are as follows: (1) understand the multiple state device design synthesis process carried out by designers, and (2) develop methods for supporting synthesis of multiple state mechanical devices to enhance the number of solution alternatives generated. Empirical studies are conducted to understand how designers currently carry out multiple state design tasks. Ten designers are given a multiple state design task and asked to generate as many solutions as possible. The designers are asked to think aloud while carrying out their synthesis processes. All these synthesis processes are video recorded, and analyzed to identify what activities are involved in the multiple state design synthesis, what the inputs are to each activity, and what the outcomes are from each activity. It has been found from these studies that design fixation is quite common, and the majority of the designers pursued developing a single solution to the given design task. A generic descriptive model of the multiple state mechanical device design synthesis process, explaining how this is carried by the designers, is developed. Based on this model, a prescriptive model of multiple state design synthesis process, explaining how the multiple state synthesis process should be carried by designers in order to develop a large solution space, is also developed. The prescriptive support, for synthesizing a large solution space for a given multiple state design task, has been evaluated. Eight engineering designers participated in the evaluation procedure, where each designer had to synthesize solutions for two, given multiple state design tasks. Results indicate that use of the prescriptive support, even without the power of a computational implementation, may have been beneficial in helping designers develop feasible solutions in a greater number of cases in a more efficient manner (that is, by considering fewer solution proposals and in similar amounts of time). All the designers who participated in this exercise gave a positive feedback regarding the prescriptive support. However, in none of the design sessions did the designers develop more than one feasible solution. This, along with various other comments from designers, indicates that a faster and more proactive support – implemented on computer – might be more useful in supporting the tasks. The various aspects for a potential computer support are discussed.

Thema der Arbeit ist die Konzeption, Entwicklung und Einführung in die Anwendung eines Entwurfssystems, das die Leistungsfähigkeit der derzeit während des Entwurfsprozesses angewandten Programme durch neue Funktionen erweitert. Die implementierte integrative Schnittstellenlösung fasst die bisher genutzten Applikationen zu einem Gesamtsystem zusammen. Der bidirektionale Datenaustausch zwischen allen integrierten Modulen verhindert zur Zeit noch notwendige Mehrfacheingaben identischer Daten. Die für die Modellierung eingesetzten CAD-Systeme bieten für die rechnerinterne Abbildung der Geometrie von Bauteilen eine hohe Funktionalität. Ungenügend ist aber die Erstellung der Funktionsstruktur mit rechentechnischen Hilfsmitteln gelöst. Dieses führt zum Entwurf neuer Produkte nahezu ohne den Einsatz der Informationstechnik und zur anschließenden Anfertigung der CAD-Modelle und Zeichnungen, wenn die Bauteile bereits in ihrer Grundstruktur bestimmt sind. Auch die Vorteile der parametrischen 3D-Modellierung, die für die Beschreibung der bauteilinternen Abhängigkeiten anwendbar ist, werden nur begrenzt genutzt. Gründe dafür liegen in der komplizierten Definition eineindeutig bestimmter Modelle und im ungenügend gelösten Datenaustausch mit externen Applikationen. Während die Ergebnisse einer Konstruktion als rechnerinterne Geometriemodelle detailliert vorliegen, werden die Daten der zugrunde liegenden Funktionsstruktur nicht oder nur zum geringen Teil erfasst. Wichtige Informationen über den Entstehungsprozess sind somit nach Abschluss einer Konstruktion nicht mehr verfügbar. Aufgrund dessen muss die gleichwertige Modellierung von Funktions- und Wirkstruktur sowie der Geometrie realisiert werden. Mit dem beschriebenen Entwurfssystem werden diese Strukturen erstellt und in einem komplexen Modell gespeichert. Im Rahmen folgender Konstruktionen kann dann nicht nur auf die Geometriedaten, sondern auch auf die Beziehungen, auf denen die Bauteilstruktur basiert, zugegriffen werden.

Though lots of numerical methods have been proposed in the literature to optimize me-chanical structures at the final stage of the design process, few designers use these tools since the first stage. However, a minor modification at the first step can bring significant change to the global performances of the structure. Usually, during the initial stage, models are based on theoretical and empirical equations, which are often characterized by mixed variables: continuous (e.g. geometrical dimensions), discrete (e.g. the cross section of a beam available in a catalogue) and/or integer (e.g. the number of layers in a composite material). Furthermore, the functions involved may be non differentiable, or even discontinuous. Therefore, classical algorithms based on the computation of sensi-tivities are no more applicable. <p><p>Consequently, to solve these problems, the most wide-spread meta-heuristic methods are evolutionary algorithms (EAs), which work as follows: the best individuals among an initial population of randomly generated potential solutions are favoured and com-bined (by specific operators like crossover and mutation) in order to create potentially better individuals at the next generation. The creation of new generations is repeated till the convergence is reached. The ability of EAs to explore widely the design space is useful to solve single-objective unconstrained optimization problems, because it gener-ally prevents from getting trapped into a local optimum, but it is also well known that they do not perform very efficiently in the presence of constraints. Furthermore, in many industrial applications, multiple objectives are pursued together. <p><p>Therefore, to take into account the constrained and multicriteria aspects of optimization problems in EAs, a new method called PAMUC (Preferences Applied to MUltiobjectiv-ity and Constraints) has been proposed in this dissertation. First the user has to assign weights to the m objectives. Then, an additional objective function is built by linearly aggregating the normalized constraints. Finally, a multicriteria decision aid method, PROMETHEE II, is used in order to rank the individuals of the population following the m+1 objectives. <p><p>PAMUC has been validated on standard multiobjective test cases, as well as on the pa-rametrical optimization of the purge valve and the feed valve of the Vinci engine, both designed by Techspace Aero for launcher Ariane 5.<p>\ / Doctorat en sciences appliquées / info:eu-repo/semantics/nonPublished

Due to the climate crisis, electrical vehicles are on the upswing. To optimize the range of electric cars, aerodynamics is an important factor to consider. Therefore, cargo boxes mounted on the tow bar, often called backboxes, have become an interesting alternative to the standard roof mounted cargo box. Backboxes are a novel product on the Swedish market, and this thesis was carried out in collaboration with the start-up company IXTAbox that produces a multi-functional backbox. In this thesis the focus was on how to improve the user experience of the product, as well as how to raise its competitiveness on the market, in order for the product to reach its full potential. In this project a thorough user study was performed with the main methods being a product walkthrough together with people new to the product in combination with contextual interviews. Findings from this were that the product did not fulfill several basic user needs, such as running a risk of damaging the car when opening the backbox lid. Another issue was the high pricing, which can be explained by the low production volume and high material cost. Thus, many areas for improvement were identified. One of these was to improve the experience of opening/closing and unlocking/locking the backbox, which the project addressed during the product development phase. Different concepts were developed, and one that utilized a code lock was chosen to bring further into detailed design. The resulting concept is a reliable and convenient design that allows the user to lock their backbox without the use of a physical key. It allows for fastening of the lid without needing to lock the box, making the locking optional for the user. In conclusion, the purpose of the thesis has been fulfilled and a future concept that improves the IXTAbox user experience has been developed. / I och med klimatkrisen är elektriska fordon på uppsving. För att optimera räckvidden hos elbilar är aerodynamiken och luftmotståndet en viktig faktor att ta hänsyn till. På grund av detta har lastboxar som fästs på dragkroken blivit ett intressant alternativ till den mer vanligt förekommande takboxen. Så kallade bakboxar är en relativt ny produkt på den svenska marknaden, och detta examensarbete utfördes i samarbete med start-up företaget IXTAbox som producerar en multi-funktionell bakbox. I denna studie har fokus varit på hur användarupplevelsen av produkten kan förbättras, såväl som hur produkten kan förstärka sin position på marknaden. Detta i syfte att undersöka hur produkten kan uppnå sin potential. En genomgående användarstudie genomfördes med huvudmetoden produktgenomgång med personer nya inför produkten i kombination med kontextuell djupintervju. Viktiga insikter från användarstudien var att produkten inte uppfyllde ett flertal grundläggande användarbehov, såsom att det finns en risk att skada billacken vid öppning av lådlocket vid användning på vissa bilmodeller. En annan smärtpunkt var den höga prissättningen, vilken kan förklaras av låg produktionsvolym och höga materialkostnader. Många aspekter som skulle kunna förbättras identifierades. En av dessa var öppning/stängning och upplåsning/låsning av lådan vilket projektet fokuserade på under produktutvecklingsfasen. Flera koncept skapades, och en togs vidare till detaljerad design. Det slutgiltiga konceptet är en pålitlig och bekväm design som tillåter användaren att låsa dess bakbox utan att behöva använda en fysisk nyckel. Den tillåter fästning av locket utan att behöva låsa lådan, vilket gör låsning av lådan valfritt för användaren. Därmed har syftet med detta examensarbete uppfyllts och ett framtida koncept som förbättrar användarupplevelsen av IXTAbox har utvecklats.

This paper describes the design, manufacturing, and testing of a novel controllable hypoxic incubator with fully functional oxygen gas control and temperature control in a humid environment. On the current market, a majority of the few hypoxic incubators use pre-mixed gas that does not offer precise control over gas concentration. The objective for this project was to create a chamber that allows the user to set the O2 concentration to varying set points of % O2 while maintaining the chamber at a constant body temperature, CO2 level, humidity, and sterility. To start the project, multiple concepts were developed for the chamber design and the control system. These concepts were compared against developed engineering specs and were evaluated amongst the team and sponsor. From there, a detailed CAD model was developed and utilized to design the structure and was used as a guide for manufacturing. The control system was prototyped on breadboards via Arduino. This breadboard testing served as the map to solder perf boards, which are utilized as the final structure for the control system. Once all parts were sourced, machined, and assembled for the final chamber and the control system, these subassemblies were integrated together with a regulated gas system via various tubing. The integrated final design underwent a variety of testing to validate the incubator design and control system. Testing was performed throughout the course of this project: material testing, gas leak testing, cell test, temperature control test, and gas control system optimization; however, the most important of these tests were those relating to the environmental control of the incubator. These tests confirmed whether the incubator design was functional as a practical incubator. Testing confirmed that O2 and temperature control maintained in spec over a short and long period of time while maintaining a humid environment. CO2 control optimization had more complications than the O2 hypoxia system. During testing CO2 concentration would typically overshoot the set point, likely due to a lack of precise control over the gas flow. CO2 variability was reduced due to optimization in the code, but not fully mitigated. Future iterations of this chamber could improve upon the CO2 control and streamline the user interface.

Stillasittande arbete och medföljande dålig hållning har kommit att bli ett stort problem i samhället. Framskjutet huvud, så kallad FHP (Forward Head Posture), är ett vanligt exempel på dålig hållning som har starka kopplingar till nacksmärta. Produkten FixaSpine är ett smarthalsband vars funktion är att komma till rätta med problemen genom att påminna användaren att räta upp sin hållning. Då produkten i dagsläget är i prototypstadiet behöver en stor mängd testning göras för att utveckla sensorteknologi och mjukvara. För att kunna testa prototyper på ett kontrollerat sätt uppstår behovet av en testanordning. Olika grad av FHP och hopsjunken rygg behöver kunna återskapas och det behöver kunna ske upprepade gånger med precision. Testanordningen bör även kunna utföra en störningsrörelse som Fixaspine ska kunna ignorera. Arbetets syfte är att möjliggöra en systematiserad testning och utveckling av FixaSpines sensorteknologi och funktionalitet, genom att ta fram en mekanisk testanordning som kan simulera dåliga hållningar samt en störningsrörelse. Genom att kartlägga olika positioner och rörelsemönster vid dålig hållning tas ett underlag fram för en mekanisk testanordning. Koncept utarbetas, beräkningar för drivning och motorer utförs, och slutligen görs konstruktion och detaljutveckling. Den resulterande testanordningen kan inta positioner som efterliknar olika grad av framskjutet huvud, som mest motsvarande en hög grad av FHP (CVA 22°). Den kan även efterlikna olika grad av hopsjunken rygg som motsvarar en rotation av bröst korgen på mer än 15°. Anordningen kan lutas framåt mer än 30° för att utföra en störningsrörelse. Dessutom kan den åstadkomma en kombination av ovan positioner och rörelser. Anordningen drivs av linjära ställdon som kan programmeras efter behov. Genom att använda testanordningen som utvecklingsredskap kan felvariabler och brus som testning på människor annars medför undvikas. På så vis underlättar testanordningen utvecklingen av FixaSpine och bidrar i förlängningen till minskad nacksmärta. / The prevalence of poor posture as a consequence of sedentary work has become a major issue in today’s society. A common example of poor posture is the so-called Forward Head Posture (FHP), which has strong associations with neck pain. FixaSpine is a smart necklace attempting to correct these problems by reminding its users to improve their posture when necessary. As the product is currently in the prototyping stage, thorough testing has to be conducted so that its software and sensor technology can be further developed. However, testing prototypes in a controlled manner has proven difficult. Hence, there is a need for a test apparatus able to simulate poor posture repeatedly and with precision. This device should be able to achieve various degrees of FHP and hunched back. Furthermore, it should also be able to perform a disruptive movement that Fixaspine ought to ignore.  The purpose of the project is to facilitate the systematized testing and development of FixaSpine’s sensor technology and functionality, by developing a mechanical test device. By analyzing lateral photographs of poor postures, positions and movement patterns are mapped, and the prerequisites for a mechanical test device determined. Concepts are drawn up, calculations for motor loads are carried out, and the final design and mechanical construction developed.  The resulting test device can simulate positions with varying degrees of Forward Head Posture. It is capable of achieving a high degree of FHP (CVA 22°). The device can simulate different degrees of hunched back equivalent to a thorax rotation of more than 15°. In addition, the device can be tilted forward more than 30°, performing a disruptive movement. Furthermore, it can perform a combination of these positions and movements. The device is powered by linear actuators that can be programmed as needed. Using it as a development tool minimizes error variables and noise otherwise prevalent when testing on humans. Subsequently, this test device is able to facilitate the development of FixaSpine and ultimately contribute to reducing neck pain.

The induction machine with a squirrel cage is a workhorse of the industry. The main advantage of an induction machine is the low manufacturing price, simple and robust construction, low maintenance requirements. However, for high-speed applications, induction machine with a squirrel cage requires design modification due to the mechanical restrictions. The objective of this thesis is to show design process, methodology and assembly of the induction machine for high-speed applications. In this thesis, the rotor dimensioning data are presented. The results are demonstrated on the design of the 6 kW, 120 000 rpm solid rotor squirrel cage induction machine. This thesis also contains calculation and design of three different electrical machine topologies for a turbo circulator application. The electrical machines are designed with 6 kW output power at 120 000 rpm. The machines are estimated by using electromagnetic, thermal, and mechanical calculations. The drawbacks and advantages of each topology under study are described. For other high-speed applications, a comparative method helps in choosing the suitable electrical machine topology by examinations of discussed criteria. Rotor design effect on the electromagnetic performance of the induction machine is shown. Mechanical stresses are calculated with Finite Element Method analysis. Various assembly technologies to produce solid rotor with squirrel cage are discuss and compare. Describe approach enables high electromagnetic performance and durable construction of the high-speed induction machine. Work is confirmed by measurement on the manufactured prototype.

Artificial human muscles have traditionally been operated through pneumatic means, and are known as Pneumatic Artificial Muscles (PAMs). Over the last several decades, Hydraulic Artificial Muscles (HAMs) have also been investigated due to their high power-to-weight ratio and human-like characteristics. Compared to PAMs, HAMs typically exhibit faster response, higher efficiency, and superior position control; characteristics which provide potential for application in rehabilitation robotics. This thesis presents a new approach to actuate artificial muscles in an antagonistic pair configuration. The detailed mechanical design of the test platform is introduced, along with the development of a dynamic model for actuating an artificial elbow joint. Also, custom manufactured Oil-based Hydraulic Artificial Muscles (OHAMs) are implemented in a biceps-triceps configuration and characterized on the test platform. Furthermore, an integrator-backstepping controller is derived for HAMs with different characteristics (stiffness and damping coefficients) in an antagonistic pair configuration. Finally, simulations and experimental results of the position control of the artificial elbow joint are discussed to confirm the functionality of the OHAMs utilizing the proposed actuating mechanism and the effectiveness of the developed control algorithm. / Graduate

[pt] A falha mecânica conhecida como fadiga é caracterizada pela iniciação e/ou propagação de trincas, causada por forças variáveis. Suas metodologias tradicionais calculam uma tensão elástica uniaxial equivalente que atua no componente, a fim de compará-la com os dados experimentais de comportamento mecânico do material do componente sob cargas uniaxiais. Esta hipótese pode levar a resultados não conservativos, por considerar que o material é igualmente sensível a tensões normais e cisalhantes, o que é falso em várias aplicações práticas. Portanto, dados torcionais e multiaxiais são necessários para melhor prever a vida em fadiga dos componentes. Para executar estes experimentos, o presente trabalho propõe uma variedade de projetos de componentes e metodologias de montagem para que se possa usar em uma máquina de tração-torção Instron 8874 uma garra hidráulica originalmente projetada para uma máquina tração pura Instron 8501. É proposto um método simplificado para estimar, por controle de deslocamento, as propriedades de fadiga de baixo ciclo em cisalhamento (gama)N, evitando assim a necessidade de usar equipamentos caros e diferentes tipos de corpos de prova. Este método é usado para caracterização das ligas Aço SAE 1020 e Alumínio 6351-T6 e os dados levantados são comparados com as propriedades medidas de fadiga de baixo ciclo em tração (epsilon)N, identificando assim se o material é mais sensível a tensões normais ou cisalhantes. Um programa numérico é usado para ajustar as curvas (epsilon)N e (gama)N nos dados experimentais, e seus procedimentos de implementação são discutidos. Por fim, são propostos e calibrados modelos de fadiga multiaxial de plano crítico mais adequados para cada material testado, com base nos dados medidos. / [en] The mechanical failure known as fatigue is characterized by the formation and/or propagation of cracks caused by variable forces. Its traditional methodologies normally calculate an equivalent uniaxial tensile stress acting on the component, in order to compare it with the known experimental mechanical behavior data of the component s material measured under uniaxial loads. This assumption can lead to non-conservative results because it considers the material to be equally sensitive to shear and tensile stresses, which is not true in a wide range of practical applications. Therefore, torsional and multiaxial experimental data is necessary to better predict the fatigue life of components. To execute those experiments, the present work proposes a variety of component designs and assembly methodologies to use on an Instron 8874 axial-torsional testing machine a hydraulic grip originally designed for an Instron 8501 uniaxial testing machine. Furthermore, a simplified method to estimate shear (gamma)N low-cycle fatigue properties via displacement-controlled experiments is proposed to avoid the need of using expensive equipment and different specimen designs, and used for characterization of SAE 1020 Steel and 6351-T6 Aluminum alloys. This data is compared with the measured tensile (epsilon)N low-cycle fatigue properties to identify if these materials are tensile or shear sensitive under multiaxial loading conditions. A numerical computing code is used to fit (epsilon)N and (gamma)N curves to the experimental data, and its implementation procedures are discussed. Finally, the most suitable critical-plane multiaxial fatigue models are proposed and calibrated for each material tested, based on the measured data.

This Master's thesis is part of the Hydrogen Embrittlement in Rolling element bearings project (HERo) initiated at Luleå University of Technology (LTU), with the primary objective of determining critical hydrogen concentrations in bearing steel for rolling element bearings. The specific aim of this Master's thesis is to design a test rig that enables the investigation of the effects of hydrogen embrittlement on rolling element bearings under load. The design process focused on ease of manufacture and assembly. The developed test rig includes an electric motor, a pneumatic load application mechanism, and an electrochemical cell. Using the leverage principle, a thrust roller bearing is loaded vertically, while it is driven by an electric motor that is connected to the bearing with a tyre coupling. The electrochemical cell, which consists of a reference electrode, counter electrode, and the test bearing as the working electrode, is used to charge the test bearing with hydrogen. The cell was designed to be easily accessible between tests to facilitate the change of thrust roller bearings. The test bench enables the analysis of rolling element bearings that are exposed to simultaneous hydrogen embrittlement and realistic operating conditions. / Detta examensarbete är en del av Hydrogen Embrittlement in Rolling element bearings-projektet (HERo) som pågår vid Luleå tekniska universitet (LTU), med huvudmålet att bestämma de kritiska vätekoncentrationerna i lagerstål för rullningslager. Det specifika målet med detta examensarbete är att konstruera en testrigg för att direkt undersöka effekten av väteförsprödning av lager i en simulerad verklig tillämpning. Designprocessen fokuserade på enkel tillverkning och montering.  Den utvecklade testriggen inkluderar en elmotor, en pneumatisk lastpåläggnings-mekanism och en elektrokemisk cell. Med hjälp av hävstångsprincipen belastas ett axiellt rullager vertikalt, medan det drivs av en elmotor via en däckkoppling. Den elektrokemiska cellen, som består av en referenselektrod, motelektrod och testlagret som arbetselektrod, används för att införa väte i lagret. Cellen har konstruerats på ett sätt som underlättar byte av testlager mellan testerna.  Testriggen skapar därmed möjligheten att analysera rullningslager som utsätts för väteförsprödning under realistiska driftförhållanden. / Diese Masterarbeit ist Teil des Hydrogen Embrittlement in Rolling element bearings-Projekts (HERo), das an der Technischen Universität Luleå (LTU) initiiert wurde, mit dem primären Ziel, kritische Wasserstoffkonzentrationen für Lageranwendungen zu bestimmen. Das spezifische Ziel dieser Masterarbeit ist es, einen Prüfstand zu konstruieren, um die Auswirkungen von Wasserstoffversprödung auf Rollenlager im Belastungszustand zu untersuchen. Der Schwerpunkt des Designprozesses lag darauf, eine einfache Fertigung und Montage des Prüfstandes zu gewährleisten.  Der entwickelte Prüfstand umfasst einen Motor, einen Mechanismus zur Lastaufbringung und eine elektrochemische Zelle. Mithilfe des Hebelgesetzes wird das Testlager vertikal belastet, während es mithilfe eines Elektromotors und einer Reifenkupplung angetrieben wird. Die elektrochemische Zelle, bestehend aus Referenzelektrode, Gegenelektrode, und dem Testlager als Arbeitselektrode, dient dazu, Wasserstoff in das Testlager einzubringen. In ihrem Design wurde darauf geachtet, dass sie zwischen den Tests leicht zugänglich ist, um den Austausch der Testproben zu erleichtern. Der Prüfstand ermöglicht somit die Analyse von Rollenlagern, die sowohl Wasserstoffversprödung als auch realistischen Betriebsbedingungen ausgesetzt sind.