This thesis utilizes the Immersed Interface Finite Element Method (IIFEM) for shape optimization and material design, while also investigating the modeling and parameterization of lung tissue for Diver Underwater Explosion (UNDEX) simulations. In the first part, a shape optimization scheme utilizing a four-noded rectangular immersed-interface element is presented. This method eliminates the need for interface fitted mesh or mesh morphing, reducing computational costs while maintaining solution accuracy. Analytical design sensitivity analysis is performed to obtain gradients for the optimization formulation, and various parametrization techniques are explored. The effectiveness of the approach is demonstrated through verification and case studies. For material design, the study combines topological shape optimization with IIFEM, providing a computational approach for architecting materials with desired effective properties. Numerical homogenization evaluates effective properties, and level set-based topology optimization evolves boundaries within the unit cell to generate optimal periodic microstructures. The design space is parameterized using radial basis functions, facilitating a gradient-based optimization algorithm for optimal coefficients. The method produces geometries with smooth boundaries and distinct interfaces, demonstrated through numerical examples. The thesis then delves into modeling the mechanical response of lung tissues, particularly focusing on hyperelastic and hyperviscoelastic models. The research adopts a phased approach, emphasizing hyperelastic model parametrization while reserving hyperviscoelastic model parametrization for future studies. Alternative methods are used for parametrization, circumventing direct experimental tests on biological materials. Representative material properties are sourced from literature or refit from existing experimental data, incorporating both empirically derived data and practical values suitable for simulations. Damage parameter quantification relies on asserted quantitative relationships between injury levels and the regions or percentages of affected lung tissue. / Doctor of Philosophy / This research explores the following themes: optimizing shapes, designing materials using repetitive identical building blocks, and understanding how divers' lungs respond to underwater explosions. When computationally analyzing structures with multiple materials, the conventional method involves creating meshes that align with material interfaces, which can be intricate and time-consuming. The Immersed Interface Finite Element Method (IIFEM) is introduced as a computational approach that simplifies this process, utilizing a uniform grid for analysis regardless of interface shape. Consider a plate with a hole or other inclusions. Shape optimization seeks the optimal hole/inclusion shape for withstanding specific loading. Traditional optimization processes necessitate iterative mesh recreation, a step circumvented by employing IIFEM. This technique also extends to creating micro-building blocks of materials, enabling the architectural design of materials with desired qualities. Materials with specific properties, like strength or flexibility can be achieved. This thesis also addresses the challenge of understanding how divers' lungs respond to underwater explosions, a crucial aspect of safety. Advanced computer models are used to mimic the behavior of lung tissue under shock loads. Directly testing materials and tissues can be difficult and restricted. Techniques like gathering data from scientific papers and refitting existing experimental data are utilized to obtain the information needed. Also, it is hard to directly measure how much damage an underwater explosion does to a diver's lungs. Thus, the level of damage was quantified based on assertions about the relationship between different injury severities and how much lung tissue is affected.

Multi-material-design (MMD) is commonly realized through the combination of thin sheet metal and fibre reinforced plastics (FRP). To maximize the high lightweight potential of the material groups within a multi-material system as good as possible, a material-adapted and particularly fibre adjusted joining technology must be applied. The present paper focuses on two novel joining technologies, the Flow Drill Joining (FDJ) method and Spin-Blind-Riveting (SBR), which were developed for joining heavy-duty metal/composite hybrids. Tests were carried out with material combinations which are significant for lightweight constructions such as aluminium (AA5083) and carbon fibre-reinforced polyamide in sheet thickness of 1.8 mm. The mechanical testing and manufacturing of those multi-material joints was investigated.

Multi-material-design (MMD) is commonly realized through the combination of thin sheet metal and fibre reinforced plastics (FRP). To maximize the high lightweight potential of the material groups within a multi-material system as good as possible, a material-adapted and particularly fibre adjusted joining technology must be applied. The present paper focuses on two novel joining technologies, the Flow Drill Joining (FDJ) method and Spin-Blind-Riveting (SBR), which were developed for joining heavy-duty metal/composite hybrids. Tests were carried out with material combinations which are significant for lightweight constructions such as aluminium (AA5083) and carbon fibre-reinforced polyamide in sheet thickness of 1.8 mm. The mechanical testing and manufacturing of those multi-material joints was investigated.

We present a level-set algorithm for topology optimisation and demonstrate its capabilities and advantages in a variety of settings. The algorithm uses discrete element densities so that interpolation schemes are avoided and the boundary of the design is always well defined. A review of the level-set method for topology optimisation, and a description of the mathematical concepts behind the level-set algorithm are given in the introductory chapters. A compact Matlab implementation of the algorithm provides explicit implementation details for the simple example of compliance minimisation with a volume constraint. The remainder of the thesis presents original results obtained using the level-set algorithm. As a new application, we use topology optimisation to maximise fracture resistance. Fracture resistance is assumed to be related to the elastic energy released by a crack propagating in a normal direction from parts of the boundary that are in tension. We develop a suitable fracture resistance objective functional, derive its shape derivative and apply the level-set algorithm to simple examples. Topology optimisation methods that involve intermediate density elements are not suitable to solve this problem because the boundary of the design is not well defined. Our results indicate that the algorithm correctly optimises for fracture resistance. As the method is computationally intensive, we suggest simpler objective functionals that could be used as a proxy for fracture resistance. For example, a perimeter penalty could be added to the compliance objective functional in conjunction with a non-linear elasticity law where the Young's modulus in tension is lower than in compression. The level-set method has only recently been applied to fluid flow problems. We utilise the level-set algorithm to minimise energy dissipation in Stokes flows in both two and three dimensions. The discrete element densities allow the no-slip boundary condition to be applied directly. The Stokes equations therefore need only be solved in the fluid region of the design: this results in significant computational savings compared to conventional material distribution approaches. In order to quantify the computational savings the optimisation problems are resolved using an interpolation scheme to simulate the no-slip boundary condition. This significant advantage of the level-set method for fluid flow problems has not been noted by other authors. The algorithm produces results consistent with those obtained by other topology optimisation approaches, and solves large-scale three dimensional problems with modest computational cost. The first examples of three dimensional periodic microstructure design with the level-set method are presented in this thesis. The level-set algorithm is extended to deal with multiple constraints. This is needed so that materials can be designed with symmetry requirements imposed on their effective properties. To demonstrate the capabilities of the approach, unit cells are designed separately to maximise conductivity and bulk modulus with an isotropy requirement. The resulting materials have properties very close to the relevant Hashin-Shtrikman bounds. The algorithm is then applied to multifunctional material design: unit cells are designed to give isotropic materials that have maximum bulk modulus and maximum conductivity. Cross-property bounds indicate the near-optimality of the microstructures obtained. The design space of the problem is extensively explored with different coefficients of the conductivity and bulk modulus in the objective and different volume constraints. We hypothesise the existence of theoretically optimal single-scale microstructures with the topologies of the computationally optimised microstructures we have found. Structures derived from the Schwartz primitive (P) and diamond (D) minimal surfaces have previously been presented as good multifunctional composites. These structures are elastically anisotropic. Although they have similar conductivity, they have stiffness properties inferior to several of the isotropic optimised microstructures.

We present a level-set algorithm for topology optimisation and demonstrate its capabilities and advantages in a variety of settings. The algorithm uses discrete element densities so that interpolation schemes are avoided and the boundary of the design is always well defined. A review of the level-set method for topology optimisation, and a description of the mathematical concepts behind the level-set algorithm are given in the introductory chapters. A compact Matlab implementation of the algorithm provides explicit implementation details for the simple example of compliance minimisation with a volume constraint. The remainder of the thesis presents original results obtained using the level-set algorithm. As a new application, we use topology optimisation to maximise fracture resistance. Fracture resistance is assumed to be related to the elastic energy released by a crack propagating in a normal direction from parts of the boundary that are in tension. We develop a suitable fracture resistance objective functional, derive its shape derivative and apply the level-set algorithm to simple examples. Topology optimisation methods that involve intermediate density elements are not suitable to solve this problem because the boundary of the design is not well defined. Our results indicate that the algorithm correctly optimises for fracture resistance. As the method is computationally intensive, we suggest simpler objective functionals that could be used as a proxy for fracture resistance. For example, a perimeter penalty could be added to the compliance objective functional in conjunction with a non-linear elasticity law where the Young's modulus in tension is lower than in compression. The level-set method has only recently been applied to fluid flow problems. We utilise the level-set algorithm to minimise energy dissipation in Stokes flows in both two and three dimensions. The discrete element densities allow the no-slip boundary condition to be applied directly. The Stokes equations therefore need only be solved in the fluid region of the design: this results in significant computational savings compared to conventional material distribution approaches. In order to quantify the computational savings the optimisation problems are resolved using an interpolation scheme to simulate the no-slip boundary condition. This significant advantage of the level-set method for fluid flow problems has not been noted by other authors. The algorithm produces results consistent with those obtained by other topology optimisation approaches, and solves large-scale three dimensional problems with modest computational cost. The first examples of three dimensional periodic microstructure design with the level-set method are presented in this thesis. The level-set algorithm is extended to deal with multiple constraints. This is needed so that materials can be designed with symmetry requirements imposed on their effective properties. To demonstrate the capabilities of the approach, unit cells are designed separately to maximise conductivity and bulk modulus with an isotropy requirement. The resulting materials have properties very close to the relevant Hashin-Shtrikman bounds. The algorithm is then applied to multifunctional material design: unit cells are designed to give isotropic materials that have maximum bulk modulus and maximum conductivity. Cross-property bounds indicate the near-optimality of the microstructures obtained. The design space of the problem is extensively explored with different coefficients of the conductivity and bulk modulus in the objective and different volume constraints. We hypothesise the existence of theoretically optimal single-scale microstructures with the topologies of the computationally optimised microstructures we have found. Structures derived from the Schwartz primitive (P) and diamond (D) minimal surfaces have previously been presented as good multifunctional composites. These structures are elastically anisotropic. Although they have similar conductivity, they have stiffness properties inferior to several of the isotropic optimised microstructures.

This master's thesis describe design and implementation of mobile and web application for supporting group work. Every team member send his work report in specific time period for compare themself with each other. In first part is described analysis and motivation for this application. Next chapters inform about similiar applications, Android platform and used technologies. In design chapter are described screens of mobile application, history of their design and web application design. In the last chapter is described implementation and testing.

This study examines whether woven metal mesh is an appropriate option for usage in beds and what material the mesh should consist of to best be suited for the purpose. The woven steel mesh’s construction was based on a reference model that consists of cross-linked rods and wires. Since the aim of the project was to reach a conclusion of the mesh’s usability in beds, different parameters were examined and taken into consideration. These parameters were the durability of the mesh when carrying human weight, acoustic properties to minimize chatter when lying on the mesh and rolling properties. The durability was examined using COMSOL multiphysics. Acoustics were studied through a literature review and rolling properties were calculated using measurements on the reference model. A material investigation was done in the database software CES EduPack. It was found that steel, stainless steel and aluminum fulfilled the requirements set on durability. Stainless steel was considered too expensive and steel too heavy. Using aluminum halves the weight of the mesh in comparison to steel but doubles the price, in this case however the weight was considered to be a parameter of greater importance overriding price.

Solar-thermochemische Redoxzyklen stellen eine vielversprechende Technologieoption zur Nutzung und Umwandlung von erneuerbaren Energiequellen dar. Durch Reduktion von Metalloxiden bei hoher Temperatur und/oder niedrigem Sauerstoffpartialdruck kann ein Material in einen Zustand überführt werden, der dazu geeignet ist, Sauerstoff aus einem Gasstrom zu entfernen oder Wasser bzw. Kohlenstoffdioxid zu spalten. Dadurch ist es möglich, Luft zu zerlegen oder Sauerstoff zu pumpen, sowie sogenannte solare Brennstoffe zu erzeugen. Eine besonders vielversprechende Materialklasse stellen dabei die Perowskite dar. Diese Materialien bilden stabile Phasen mit sehr unterschiedlichen Zusammensetzungen. In dieser Arbeit wird gezeigt, wie diese Perowskit-Oxide in thermochemischen Redoxzyklen verwendet werden können und die Mechanismen hinter diesen Redoxreaktionen werden mit in-situ-Röntgenuntersuchungen aufgeklärt. Es wird auch gezeigt, dass die kinetischen Parameter der Oxidationsreaktion sehr vielversprechend sind. Zudem wird demonstriert, wie feste Lösungen aus Perowskiten in einem weiten Bereich verschiedener Zusammensetzungen hergestellt werden können und wie die Zusammensetzung der Perowskite die Phasenbildung und Stabilität beinflusst. Mit diesem Wissen wird ein Schwerpunkt dieser Arbeit auf die thermodynamischen Eigenschaften dieser Perowskite gelegt. Eine neue Methode der gezielten Materialentwicklung wird demonstriert, welche darauf basiert, den Toleranzfaktor und die thermodynamischen Eigenschaften der Perowskite gezielt einzustellen. Sowohl experimentelle, als auch theoretische Untersuchungen werden durchgeführt, letzere basierend auf Dichtefunktionaltheorie (DFT) im Rahmen von „Materials Project“. Über 240 Perowskit-Brownmillerit-Paare wurden untersucht. Detaillierte Modelle wurden entwickelt, um die thermodynamischen Eigenschaften solcher fester Lösungen aus Perowskiten als eine Funktion der Temperatur, des Sauerstoffpartialdrucks, und der Sauerstoff-Fehlstellenkonzentration 𝛿 zu beschreiben. Mit Hilfe dieser Funktionen wurde ein interaktiver Beitrag im Rahmen von Materials Project entwickelt, mit dem Materialeigenschaften in einem weiten Bereich verschiedener Bedingungen untersucht werden können. Darin ist auch eine Perowskit-Suchmaschine enthalten. Diese verwendet ein vereinfachtes Prozessmodell, um den materialspezifischen Energiebedarf von Redoxzyklen auszuwerten und ermöglicht es so, das effizienteste Material basierend auf den Prozessbedingungen auszuwählen. Es konnten neue Redoxmaterialien zur Anwendung in thermochemischen Kreisprozessen identifiziert werden und es wurde festgestellt, dass Perowskite die Effizienz der solaren Brennstofferzeugung bei vergleichsweise niedrigen Reduktionstemperaturen von 1300-1400 °C erhöhen können. So soll eine höhere Reaktorlebensdauer erreicht werden. Es wird auch diskutiert, welche Faktoren die Prozesseffizienz beeinflussen und es werden Ideen präsentiert, welche Schritte nötig sind, um eine kommerzielle Nutzung zu ermöglichen. Der wichtigste Faktor ist dabei die Wärmerückgewinnungseffizienz zwischen Feststoffen. Durch die Veröffentlichung aller Daten im Rahmen von MPContribs/Materials Project durch das Erstellen von interaktiven Graphen wird eine wertvolle Ressource zur schnelleren und zielgerichteten Materialentwicklung bereitgestellt. / Solar-thermochemical redox cycles are a promising technological option in the framework of utilization and conversion of renewable energy. By reducing metal oxides at high temperature and/or low oxygen partial pressure, one can generate a material in a state which can be used to capture oxygen from a gas stream or split water or carbon dioxide. By this means, air can be separated, oxygen can be pumped, or so-called solar fuels can be generated. One especially attractive materials class for application in such redox cycles is constituted by perovskites. These materials form stable phases over a large compositional range. Within this work, we show how these perovskite oxides can be applied in thermochemical redox cycles and study the mechanisms behind these redox reactions using in-situ X-Ray techniques. We also show that the kinetic properties of the oxidation reaction are very appealing. It is furthermore presented how perovskite solid solutions can be formed over a large compositional range and how phase formation and stability are affected by the perovskite composition. Based on this knowledge, the focus of this work is set on the materials thermodynamics. A new method of rational perovskite materials design is developed by adjusting the tolerance factor of the perovskites and their thermodynamics. Both experimental and theoretical materials development are conducted, the latter based on density functional theory (DFT) within the framework of the online resource “Materials Project”. Over 240 perovsite-brownmillerite pairs are included in the search. Detailed models describing the thermodynamics of such perovskite solid solutions are established which allow describing the perovskite redox properties as a function of the temperature, oxygen partial pressure, and oxygen non-stoichiometry 𝛿. Using these functions, we developed an interactive tool within the framework of Materials Project, which can be used to model materials properties for a large range of conditions and also serves as a perovskite search engine. This search engine uses a simplified process model to evaluate the material-specific energy demand of a thermochemical redox process and allows finding the most efficient materials choice for a large range of different operational parameters. We could identify new redox materials for application in such processes and found that perovskites can lead to more efficient thermochemical fuels production than the state of the art, especially if the reduction temperature is lowered to 1300-1400 °C to reach higher reactor longevity. It is also discussed which factors affect the overall process efficiency to which extent, and suggestions are given which steps are necessary for a commercialization of such redox processes. The most important factor is the solid-solid heat recovery efficiency. By making all this data publicly available in the framework of MPContribs/Materials Project through providing user-controlled interactive graphs, we are providing a valuable resource for accelerating the discovery and use of new redox materials.

Lärarhandledningar för matematikundervisning kan designas på olika sätt och ger därigenom olika typer av stöd för läraren att genomföra undervisningen. En lärarhandlednings design kan alltså mediera idéer och direktiv som kan påverka lärarens genomförande av undervisning. Syftet med denna studie är att undersöka om och i så fall hur läromedels design kan bidra till att påverka undervisningens karaktär. Syftet uppfylls genom observationer av fyra matematiklektioner som utgick ifrån två läromedel med olika design, med uppföljande intervjuer. Resultatet, som är en karaktärisering av undervisningen som observerades utifrån de två olika läromedlen, indikerar att designen av en lärarhandledning på flera sätt medierar agerande i planering och genomförande av undervisning. / Teachers’ guides in mathematics can be designed in different ways and thereby provide various supports for the teacher to carry out teaching activities. A teachers´ guide in mathematics can mediate ideas and directives that affects the teaching strategies in the classroom. The aim of this study is to investigate whether, and in that case how, the design of the learning materials can contribute to affect the nature of the teaching. The aim is fulfilled by observing four mathematic lessons which was based on two learning materials with different designs, with follow-up interviews. The results, which is a characterization of the teaching that was observed based on the two different teaching materials indicates that the design of a teacher's guide in several ways mediates action in planning and implementation of teaching.

<p>The design of vehicle components for crashworthiness is one of the most challenging problems in the automotive industry. The safety of the occupants during a crash event relies on the energy absorption capability of vehicle structures. Therefore, the body components of a vehicle are required to be lightweight and highly integrated structures. Moreover, reducing vehicle weight is another crucial design requirement since fuel economy is directly related to the mass of a vehicle. In order to address these requirements, various design concepts for vehicle bodies have been proposed using high-strength steel and different aluminum alloys. However, the price factor has always been an obstacle to completely replace regular body steels with more advanced alloys. To this end, the integration of numerical simulation and structural optimization techniques has been widely practiced addressing these requirements. Advancements in nonlinear structural design have shown the promising potential to generate innovative, safe, and lightweight vehicle structures. In addition, the implementation of structural optimization techniques has the capability to shorten the design cycle time for new models. A reduced design cycle time can provide the automakers with an opportunity to stay ahead of their competitors. During the last few decades, enormous structural optimization methods were proposed. A vast majority of these methods use mathematical programming for optimization, a method that relies on availability sensitivity analysis of objective functions. Thus, due to the necessity of sensitivity analyses, these methods remain limited to linear (or partially nonlinear) material models under static loading conditions. In other words, these methods are no able to capture all non-linearities involved in multi-body crash simulation. As an alternative solution, heuristic approaches, which do need sensitivity analyses, have been developed to address structural optimization problems for crashworthiness. The Hybrid Cellular Automaton (HCA), as a bio-inspired algorithm, is a well-practiced heuristic method that has shown promising capabilities in the structural design for vehicle components. The HCA has been continuously developed during the last two decades and designated to solve specific structural design applications. Despite all advancements, some fundamental aspects of the algorithm are still not adequately addressed in the literature. For instance, the HCA numerically implemented as a closed-loop control system. The local controllers, which dictate the design variable updates, need parameter tuning to efficiently solve different sets of problems. Previous studies suggest that one can identify some default values for the controllers. However, still, there is no well-organized strategy to tune these parameters, and proper tuning still relies on the designer’s experience.</p> <p> </p> <p> Moreover, structures with multiple materials have now become one of the perceived necessities for the automotive industry to address vehicle design requirements such as weight, safety, and cost. However, structural design methods for crashworthiness, including the HCA, are mainly applied to binary structural design problems. Furthermore, the conventional methods for the design of multi-material structures do not fully utilize the capabilities of premium materials. In other words, the development of a well-established method for the design of multi-material structures and capable of considering the cost of the materials, bonding between different materials (especially categorical materials), and manufacturing considering is still an open problem. Lastly, the HCA algorithm relies only on one hyper-parameter, the mass fraction, to synthesize structures. For a given problem, the HCA only provides one design option directed by the mass constraint. In other words, the HCA cannot tailor the dynamic response of the structure, namely, intrusion and deceleration profiles.</p> <p> </p> <p>The main objective of this dissertation is to develop new methodologies to design structures for crashworthiness applications. These methods are built upon the HCA algorithm. The first contribution is about introducing s self-tuning scheme for the controller of the algorithm. The proposed strategy eliminates the need to manually tune the controller for different problems and improve the computational performance and numerical stability. The second contribution of this dissertation is to develop a systematic approach to design multi-material crashworthy structures. To this end, the HCA algorithm is integrated with an ordered multi-material SIMP (Solid Isotropic Material with Penalization) interpolation. The proposed multi-material HCA (MMHCA) framework is a computationally efficient method since no additional design variables are introduced. The MMHCA can synthesize multi-material structures subjected to volume fraction constraints. In addition, an elemental bonding method is introduced to simulate the laser welding applied to multi-material structures. The effect of the bonding strength on the final topology designs is studied using numerical simulations. In the last step, after obtaining the multi-material designs, the HCA is implemented to remove the desired number of bonding elements and reduce the weld length.</p> <p> </p> <p>The third contribution of this dissertation is to introduce a new Cluster-based Structural Optimization method (CBSO) for the design of multi-material structures. This contribution introduces a new Cluster Validity Index with manufacturing considerations referred to as CVI_m. The proposed index can characterize the quality of the cluster in structural design considering volume fraction, size, interface as a measure of manufacturability. This multi-material structural design approach comprises three main steps: generating the conceptual design using adaptive HCA algorithm, clustering of the design domain using Multi-objective Genetic Algorithm (MOGA) optimization. In the third step, MOGA optimization is used to choose categorical materials in order to optimize the crash indicators (e.g., peak intrusion, peak contact force, load uniformity) or the cost of the raw materials. The effectiveness of the algorithm is investigated using numerical examples.</p>