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In an attempt to improve the quality in finite element analysis of thermoformed components, a method for predicting the thickness distribution is presented. The strain induced anisotropic material behaviour in the amorphous polymers of concern is also taken into account in the method. The method comprises of obtaining raw material data from experiments, followed by a simulation of the vacuum thermoforming process where hyperelastic material behaviour is assumed. The theory of hyperelasticity that was applied was based on the Ogden model and implemented in the FE-software LS-DYNA. Material behaviour from thermoformed prototypes is examined by experiments and implemented together with the mapped results from the thermoforming simulation in a succeeding FE-model. For the latter, the three-parameter Barlat model was suggested, giving the possibility to account for anisotropic material behaviour based on an initial plastic strain.

This work explores the use of carbon-infiltrated carbon nanotube (CI-CNT) forests as a material for fabricating compliant MEMS devices. The impacts of iron catalyst layer thickness and carbon infiltration time are examined. An iron layer of 7nm or 10nm with an infiltration time of 30 minutes produces CI-CNT best suited for compliant applications. Average maximum strains of 2% and 2.48% were observed for these parameters. The corresponding elastic moduli were 5.4 GPa and 4.1 GPa, respectively. A direct comparison of similar geometry suggested CI-CNT is 80% more flexible than single-crystal silicon. A torsional testing procedure provided an initial shear modulus of about 5 GPa for the 7-nm, 30-min CI-CNT. The strain and elastic modulus values were used to design numerous functional devices which were then fabricated in CI-CNT. A series of compliant cell restraint mechanisms were developed, assessed, and revised. A passive restraint with no moving parts was found to be both the most effective design and the easiest design to produce economically. A refined version of the passive restraint has been released commercially. Another series of designed devices successfully demonstrates the implementation of CI-CNT LEM designs.

This thesis deals with the possibilities of cutting strong steel metal sheets by means of laser and problems rising from the incision, their technological investigation. The basic philosophy consists on the research of the interaction between laser bunch and material, depending on the position of focal poin and sequential results in spec. heat. It determines the main parametres of the incision (from the total quantities and matematical description) which have the biggest effect on the occurence of wide cut and perhaps even on the quality of products and consequential optimalization of these quantities.

This thesis deals with laser cutting of metal sheets from selected steel producers. The basics of laser technologies, especially in industrial use, are described in the introductory part. There the material requirements are described from the point of view of laser cutting. The comparison of materials from different steel producers is made from different angles in the practical part. The conclusion is dedicated to the evaluation of achieved results.

UV- und lichthärtenden Acrylatklebstoffen steht ein breites Anwendungsspektrum im Konstruktiven Glasbau offen. Ihr farbloses und klares Erscheinungsbild fördert eine Konstruktion, die transparent und leicht wirken soll. Kurze Aushärtezeiten, die sich im Sekunden- oder einstelligen Minutenbereich bewegen, ermöglichen eine schnelle Herstellung und reduzieren die Lagerzeiten. Die geklebten Konstruktionen können direkt weiterverarbeitet werden. Durch diese Vorteile heben sie sich von den Silikonklebstoffen ab, die für ausge-wählte Anwendungen im Fassadenbau (Structural-Sealant-Glazing-Systems - SSGS) bauaufsichtlich zugelassen sind. Gegenstand dieser Arbeit ist die Aufstellung von Empfehlungen zur Planung und Berechnung struktureller Klebungen mit strahlungshärtenden Acrylaten. Dafür werden Klebstoffe an dem reinen Material sowie in Verbindungen mit Glas und Metall untersucht. Für ein umfangreiches Bild über das Verhalten des Materials bieten sich Substanzprüfkörper an, die mit überschaubarem Aufwand eine Auswertung verschiedener Einflüsse - beispielsweise Temperatur und Prüfgeschwindigkeit - erlauben. An in-situ-Prüfkörpern kann der Klebstoff in der Verbindung betrachtet werden. Durch Wechselwirkungen zwischen Klebstoff und Fügeteil bildet sich eine sogenannte Grenzschicht aus, die gradierte Eigenschaften besitzt und die Materialkennwerte - besonders bei dünnen Klebfugen - beeinflusst. Weiterhin erlauben diese Prüfkörper eine Aussage über das Tragverhalten der Klebverbindung. Um das Potenzial der Acrylatklebungen in der Glasarchitektur aufzuzeigen und in der Anwendung zu prüfen, werden Bauteile mit punktförmig geklebten Halterungen untersucht. Absturzsicherungen werden statischen und dynamischen Belastungen unterworfen. An Überkopfverglasungen werden Trag- und Resttragfähigkeitsuntersuchungen durchgeführt. Bauteile im Freien geben Aufschluss über das Alterungsverhalten unter natürlichen klimatischen Bedingungen. / UV and light curing acrylates present a whole host of possibilities for the implementation of glass construction. Their clear and colourless appearance produces a transparent and lightweight construction. Short curing times consisting of no more than mere minutes allow for quick production with minimal downtime within the overall process. Processing can be resumed immediately once bonding has occurred. The advantages of acrylates can be compared to the characteristics and properties of adhesive silicones which have been widely approved by building authorities for specific façade applications (Structural-Sealant-Glazing-Systems - SSGS). The subject matter of this study is the development of auxiliary tools to plan and design adhesively bonded joints of UV and light curing acrylates. These adhesives are, therefore, analysed both generally as bulk material and in applications as a joint between glass and metal. The use of dog bone shaped specimens is recommended to analyze the material behaviour under a variety of influence factors such as temperature and testing rate. The bonded joints of test specimens provide an opportunity to examine the interaction between the adhesive and the materials to which they are adhered. An interface with graded properties is formed based upon the interactions between adhesive joints and each particular substrate. Further on, bonded specimens enable the development of a statement concerning the load-bearing capacity of joints. Constructions having spot bonded joints are tested to demonstrate the potential use of acrylic joints in architectural glass treatments. Safety barriers are tested under both static and dynamic loads. Sloped roof systems are tested to substantiate load-bearing capacity and to verify any residual carrying capacity. Components are exposed to natural weathering in order to examine the affects of ageing on the adhesive.

Additive manufacturing (AM) is a technology that inverts the procedure of traditional machining. Instead of starting with a billet of material and removing unwanted parts, the AM manufacturing process starts with an empty workspace and proceeds to fill this workspace with material where it is desired, often in a layer-by-layer fashion. Materials available for AM processing include polymers, concrete, metals, ceramics, paper, photopolymers, and resins. This thesis is concerned with electron beam melting (EBM), which is a powder bed fusion technology that uses an electron beam to selectively melt a feedstock of fine powder to form geometries based on a computer-aided design file input. There are significant differences between EBM and conventional machining. Apart from the process differences, the ability to manufacture extremely complex parts almost as easily as a square block of material gives engineers the freedom to disregard complexity as a cost-driving factor. The engineering benefits of AM also include manufacturing geometries which were previously almost impossible, such as curved internal channels and complex lattice structures. Lattices are lightweight structures comprising a network of thin beams built up by multiplication of a three-dimensional template cell, or unit cell. By altering the dimensions and type of the unit cell, one can tailor the properties of the lattice to give it the desired behavior. Lattices can be made stiff or elastic, brittle or ductile, and even anisotropic, with different properties in different directions. This thesis focuses on alleviating one of the problems with EBM and AM, namely the relatively few materials available for processing. The method is to take a closer look at the widely used stainless steel 316LN, and investigate the possibility of processing 316LN powder via the EBM process into both lattices and solid material. The results show that 316LN is suitable for EBM processing, and a processing window is presented. The results also show that some additional work is needed to optimize the process parameters for increased tensile strength if the EBM-processed material is to match the yield strength of additively laser-processed 316L material. / <p>Vid tidpunkten för framläggningen av avhandlingen var följande delarbete opublicerat: delarbete 3 (inskickat).</p><p>At the time of the defence the following paper was unpublished: paper 3 (submitted).</p>

Syfte: En fasad måste vara robust för att fylla sin funktion och materialet måste kunna stå emot angrepp utifrån, biologiska, kemiska och fysikaliska faktorer. Trä och tegel är eftertraktade som fasadmaterial för dagens nybyggda bostadshus. Eftersom olika material reagerar olika på angrepp är det viktigt att det finns skillnader i underhållsstrategier beroende på vilket fasadmaterial som används. Underhållsarbetet är en faktor som påverkar beslutet på fasadmaterial. Undersökningen ger ett underlag inför valet mellan materialen genom att utveckla underhållsstrategier för respektive material. Metod: För att uppnå målet med arbetet har tre metoder använts för att samla in empiri Dessa är litteraturstudie, intervjuer och dokumentanalys. I litteraturstudien samlades information från olika källor på internet in. Dessa källor hjälpte till att bygga ett teoretiskt ramverk om fastighetsförvaltning och underhållsstrategier. Dokumenten och intervjuerna gav praktisk kunskap om förhållningssätt till underhåll. Metoderna var lämpliga eftersom de tillsammans gav teoretisk såväl som praktisk kunskap kring material och underhåll. Den insamlade empirin analyserades och jämfördes för att kunna besvara frågeställningarna och uppnå målet. Resultat: Idag finns olika underhållsstrategier på trä- och tegelfasader. Den generella åsikten är att trä kräver fler underhållsåtgärder än tegel. Det har dock visat sig att det även förekommer problem med till exempel frostsprängning i större omfattning än vad som tidigare antagits. Underhållsplaner upprättas ofta efter grundlig undersökning av en byggnads egenskaper och kartläggning av dess underhållsbehov. Dessa planer används inte regelbundet hos förvaltningsföretag men det finns en önskan bland vissa förvaltare att ha en mer strukturell underhållsplanering i framtiden. Kategorisering av skador och tillkommande underhållsåtgärder kan användas vid upprättande av underhållsplaner. Ett sådant system är Monument Damage Diagnosis System, förkortat MDDS. Underhållsplaner kan också utformas som stegvisa processer som kan användas tillsammans med databaser över fasadens egenskaper och nödvändiga underhållsåtgärder. Konsekvenser: Denna rapport kommer att ge aktörer inom byggbranschen kunskap och olika strategier vid fasadunderhåll. Konsekvenserna blir att: Företag inom byggbranschen upprättar underhållsplaner mer i framtiden. Det upprättas strukturerade bedömningar om risker kopplade till material, byggnadsdel och yttre påverkan. För- och nackdelarna med trä- och tegelfasader uppmärksammas i högre grad än idag. Många riskfaktorer för tegel såsom frostsprängning har tidigare inte beaktats tillräckligt. Det rekommenderas att byggföretag tar till sig den forskning som finns av underhåll av trä- respektive tegelfasader. Eftersom trä är billigare än tegel i byggskedet men dyrare vid underhåll behöver dessa företag göra fler undersökningar om båda materials för- och nackdelar ur ekonomisk synpunkt. Byggföretag behöver om förutsättningarna finns även upprätta underhållsplaner eftersom dessa planer leder till att fel upptäcks tidigare och därmed minskar kostnaderna på lång sikt. Begränsningar: Resultatet är enbart tillämpbart på fasader av trä och fasader av tegel.  Vidare kan resultatet bara tillämpas på bostadshus eftersom inga andra byggnadstyper har undersökts. Underhållsstrategin som utvecklats i rapporten kan i grunden användas i alla typer av klimat dock måste alltid lokala klimatförhållanden beaktas när strategin appliceras i praktiken. Att upprätta en underhållsplan kräver även en god ekonomi därför är det inte säkert att rapportens underhållsstrategi alltid kan upprättas i verkligheten om det finns ekonomiska hinder.  Litteraturstudien har studerat underhållsstrategier på global nivå medan dokumentanalysen och intervjuerna har fokuserat på de lokala förhållandena i Sverige. / Purpose: A façade must be robust to be able to fulfil its role and the material must be able to withstand exterior threats. These threats could be biological, chemical, or physical. Wood and brick are popular as façade materials when it comes to the newly constructed residential buildings of today. Since different materials react different on threats it is vital that there are separate maintenance strategies depending on the choice of façade material. The examination gives the choice between the materials a basis by developing maintenance strategies for respective material Method: To achieve the goal of the project, three methods have been used to collect empirical data. These methods are literature study, interviews, and document analysis. In the literature study, information from different sources on the internet were collected. The sources helped building a theoretical about property management and maintenance management. The document and interviews provided practical knowledge about maintenance approaches. The methods were suitable since together they provided both theoretical and practical knowledge about materials and maintenance. The collected data was analysed and compared to answer the questions and achieve the projects goal. Findings: Today there are different maintenance strategies for wood and brick facades. The general opinion is that wooden facades require more maintenance than brick facades. Although brick facades have had more problems with for example frost shattering than what was assumed before. Maintenance plans are often established after thorough investigation of a building’s properties and mapping of its maintenance needs. These plans aren’t used regularly among property managers but there’s a wish among some of them to have more structural maintenance planning in the future. Categorization of damages and additional maintenance activities can be used when establishing maintenance plans. One such system is Monument Damage Diagnosis System, abbreviated MDDS. Maintenance plans could also be formulated as step-by-step processes that could be used together with databases of a façade's properties and necessary maintenance actions. Implications: This study will give actors in the construction industry better knowledge about different strategies for façade maintenance. The consequences will be: That companies in the construction industry establish maintenance plans more in the future. That structural evaluations of risks depending on material, building component and external influence are established That strengths and weaknesses with wooden facades and brick facades are paid attention to more in the future. Many risk factors affecting brick facades has not been sufficiently acknowledged before. It is recommended that construction companies take note of current research on maintenance of wooden and brick facades. Since wood is cheaper to build with but more expensive to maintain than brick companies need to do more studies about these materials strengths and weaknesses. Construction companies also need to establish and follow maintenance plans if the conditions are right since that would lead to damages being discovered earlier and therefore decreases costs in a long term. Limitations: The result is only applicable on wooden and brick facades. Furthermore, the result can only be applied on residential houses since no other type of building has been examined. The maintenance strategy that has been developed in the report is in can be used in all climates, but local climate circumstances must always be considered then the strategy is applied in practice. Establishing a maintenance plan requires a good economy therefore it is not certain that the report’s maintenance strategy will always be possible to establish in reality if there are economical limits. The literature study has examined maintenance strategies on a global scale while the document analysis and the interviews has focused on the local circumstances in Sweden.

X-ray detector windows must be thin enough to transmit sufficient low-energy x-rays, yet strong enough to withstand up to an atmosphere of differential pressure. Traditional low-energy x-ray windows consist of a support layer and pressure membrane spanning that support. Numerical modeling of several x-ray windows was used to show that both low- and high-energy x-ray transmission can be improved by adding a secondary support structure. Finite element analysis of the x-ray window models showed that the stress from a typical applied load does not exceed the ultimate strength or yield strength of the respective materials. The specific x-ray window models developed in this work may serve as a foundation for improving commercial windows, especially those geared toward low-energy transmission. For local mechanical film testing, microcantilevers were cut in suspended many-layer graphene using a focused ion beam. Multipoint force-deflection mapping with an atomic force microscope was used to record the compliance of the cantilevers. These data were used to estimate the elastic modulus of the film by fitting the compliance at multiple locations along the cantilever to a fixed-free Euler-Bernoulli beam model. This method resulted in a lower uncertainty than is possible from analyzing only a single force-deflection. The breaking strength of the film was also found by deflecting cantilevers until fracture. The average modulus and strength of the many-layer graphene films are 300 GPa and 12 GPa, respectively. The multipoint force-deflection method is well suited to analyze films that are heterogeneous in thickness or wrinkled. Bioimpedance can be measured by applying a known current to the tissue through two (current carrying) electrodes and recording the resulting voltage on two different (pickup) electrodes. Bioimpedance has been used to detect heart rate, respiration rate, blood pressure, and blood glucose. A wrist-based wearable bioimpedance device can measure heart rate by detecting the minute impedance changes caused by the modulation of blood volume in the radial artery. Using finite element analysis, I modeled how electrode position affects sensitivity to pulsatile changes. The highest sensitivity was found to occur when the pickup electrodes were centered over the artery. In this work, we used microfabricated carbon infiltrated-carbon nanotube electrodes to measure the change in contact bioimpedance for dry electrodes, and identical electrodes with a wet electrolyte, on five human subjects in the range of 1 kHz to 100 kHz. We found that the acclimated skin-electrode impedance of the dry electrodes approached that of the wet electrodes, especially for electrodes with larger areas. We also found that the acclimation time does not appear to depend on electrode area or frequency. The skin-electrode impedance after acclimation does depend on electrode area and frequency, decreasing with both. This work shows that if care is taken during the acclimation period, then dry carbon composite electrodes can be used in bioimpedance wearable applications.

<p>  </p> <p>This thesis is motivated by the author’s observation that no systematic methodology is available to characterize and model mechanical behaviors of 3D printed parts in terms of their elastic modulus and critical loading capacities. Note that the more controlled and steadier printing process is, the easier the mechanical properties parts can be predicted. This research focuses on the methods for the prediction and validation of mechanical properties of 3D printed parts, and the focus is the responses of the printed parts subjected to tensile loads. The mathematic models are derived to characterize the mechanical properties of a part along three principal directions, and the models are validated experimentally by following the American Society for Testing and Materials (ASTM) D638 testing standards. It is assumed that a unidirectional plane stress occurs to each lamina to (1) simplify a compliance matrix with a size 3 by 3 and (2) characterize the mechanical properties by the elastic modules and strengths in three principal directions. Two mathematical models are developed using the experimental data from the classical laminate theory and finite element analysis (FEA) by the SolidWorks. Both of the developed models are used to predict the ultimate tensile strength and Young’s modulus of the specimens that are printed by setting different raster angles on different layers. This thesis work aims to (1) gain a better understanding of the impact of printing parameters on the strengths of printed parts and (2) explore the feasibility of using the classical laminate theory to predict the mechanical properties of the parts printed with different raster angles and patterns. To validate the proposed mathematic models, parts by FDM are tested by following the ASTM testing standards; moreover, it testifies if the selected ASTM-D638 is suitable to test 3D printed parts by FDM. </p>