Gitterstrukturen sind ein prominentes Beispiel für die Designfreiheiten der Additiven Fertigung. Während regelmäßige Gitterstrukturen einfacher zu konstruieren sind, bieten unregelmäßige Varianten größere Spielräume zur individuellen Anpassung. In dieser Arbeit wird eine Vorgehensweise zur Synthese optimierter unregelmäßiger Gitterstrukturen auf Voronoi-Basis erarbeitet, wobei nach einer Vorstellung der mathematischen Grundlagen und relevanten Literatur die Forschungsfragen sowie der Forschungsumfang konkretisiert werden. Zunächst wird anhand des Produktentwicklungsprozesses nach Weber eine geeignete Vorgehensweise zur gesteuerten Synthese einer Voronoi-Gitterstruktur gemäß funktionalen Anforderungen modelliert und die zu erarbeitenden Komponenten werden ermittelt. Basierend auf den geometrischen Eigenschaften der Voronoi-Zellen werden Metriken definiert, für deren ortsaufgelöste Spezifikation eine Datenstruktur vorgestellt wird. Zur zielgerichteten Manipulation der Zellform werden mittels numerischer und analytischer Untersuchungen die Auswirkungen der Position der benachbarten Saatpunkte auf die einzelnen Metriken untersucht. Zur bestmöglichen Positionierung der Saatpunkte wird das resultierende Optimierungsproblem charakterisiert, mögliche Lösungsansätze evaluiert und als Vorzugsvariante ein Memetischer Algorithmus implementiert. Dieser stellt eine Kombination aus einem populationsbasierten Evolutionären Algorithmus zur globalen Suche und der Nutzung des Wissens zur zielgerichteten Zellformmanipulation zur lokalen Suche dar. Eine Verifikation des implementierten Algorithmus erfolgt anhand eines zweidimensionalen Beispielbauteils. Das erarbeitete Vorgehen wird durch den simulativen Vergleich einer optimierten mit einer nicht-optimierten und einer regelmäßigen Gitterstruktur validiert, wobei eine Hüftschaft-Endoprothese als Beispielbauteil dient. Eine Rekapitulation des Inhaltes und ein Ausblick auf mögliche weiterführende Forschungsthemen schließen die Arbeit ab. / Lattice structures are a prominent example of the design freedom offered by additive manufacturing. While regular lattice structures are easier to design, irregular variants offer greater scope for customization. In this thesis, a procedure for the synthesis of optimized irregular lattice structures based on Voronoi is developed, whereby the research questions and the scope of research are specified after a presentation of the mathematical principles and relevant literature. First, a suitable procedure for the controlled synthesis of a Voronoi lattice structure according to functional requirements is modeled using Weber's product development process, and the components to be developed are defined. Based on the geometric properties of the Voronoi cells, metrics are defined, and a data structure is presented for their spatial specification. To manipulate the cell shape in a targeted manner, the effects of the position of the neighboring seed points on the individual metrics are investigated through numerical and analytical studies. For the best possible positioning of the seed points, the resulting optimization problem is characterized, possible solution strategies are evaluated, and a memetic algorithm is implemented as the preferred variant. This represents a combination of a population-based evolutionary algorithm for global search and the use of knowledge for targeted cell shape manipulation for local search. The implemented algorithm is verified using a two-dimensional example. The developed procedure is validated by the simulative comparison of an optimized with a non-optimized and a regular lattice structure, whereby a hip stem endoprosthesis serves as an example component. A recapitulation of the content and an outlook on possible further research topics concludes the thesis.

A generalized software capability has been developed for the pin-wise loading optimization of light water reactor (LWR) fuel lattices with the enhanced flexibility of control variables that characterize heterogeneous or blended target pins loaded with non-standard compositions, such as minor actinides (MAs). Furthermore, this study has developed the software coupling to evaluate the performance of optimized lattices outside their reflective boundary conditions and within the realistic three-dimensional core-wide environment of a LWR. The illustration of the methodologies and software tools developed helps provide a deeper understanding of the behavior of optimized lattices within a full core environment. The practical applications include the evaluation of the recycling (destruction) of “undesirable” minor actinides from spent nuclear fuel such as Am-241 in a thermal reactor environment, as well as the timely study of planting Np-237 (blended NpO2 + UO2) targets in the guide tubes of typical commercial pressurized water reactor (PWR) bundles for the production of Pu-238, a highly “desirable” radioisotope used as a heat source in radioisotope thermoelectric generators (RTGs). Both of these applications creatively stretch the potential utility of existing commercial nuclear reactors into areas historically reserved to research or hypothetical next-generation facilities. In an optimization sense, control variables include the loadings and placements of materials; U-235, burnable absorbers, and MAs (Am-241 or Np-237), while the objective functions are either the destruction (minimization) of Am-241 or the production (maximization) of Pu-238. The constraints include the standard reactivity and thermal operational margins of a commercial nuclear reactor. Aspects of the optimization, lattice-to-core coupling, and tools herein developed were tested in a concurrent study (Galloway, 2010) in which heterogeneous lattices developed by this study were coupled to three-dimensional boiling water reactor (BWR) core simulations and showed incineration rates of Am-241 targets of around 90%. This study focused primarily upon PWR demonstrations, whereby a benchmarked reference equilibrium core was used as a test bed for MA-spiked lattices and was shown to satisfy standard PWR reactivity and thermal operational margins while exhibiting consistently high destruction rates of Am-241 and Np to Pu conversion rates of approximately 30% for the production of Pu-238.

[pt] Desenvolver e construir uma prótese ou órtese com fácil adaptação para o usuário ainda é um grande desafio na área de engenharia em geral. Além disso, o uso de elementos eletromecânicos insere a autonomia e a portabilidade como fatores de dificuldade na construção. Outro ponto é que variações de fatores humanos, como espasticidade, tônus muscular ou alterações decorrentes de doenças como paralisia cerebral ou lesão nervosa, interferem na construção do aparelho. Deste modo, a construção de uma órtese é um trabalho desafiador e multidisciplinar, que envolve uma análise profunda e detalhada desde a aplicação até a construção propriamente dita. O uso de técnicas de indústria 4.0 para tornar a órtese confortável, leve e de facil uso é fundamental para isso, assim como a análise e processamento de biosinais e o controle, fazendo com que cada etapa estaja ligada e ajustada para que o funcionamento esteja correto. Esta tese tem como objetivo avaliar os métodos teóricos e experimentais de construção e avaliação dinâmica de uma bio-órtese de membros superiores utilizando o conceito de indústria 4.0, processos de manufatura digital, otimização multiestrutural, processamentos de biossinais e técnicas de controle não linear. Este estudo foi motivado pelo avanço do uso da manufatura digital no campo da biomedicina, pelo grande desafio sob o ponto de vista de controle, pela variabilidade que esses processos podem ter na construção de órteses na melhoria da qualidade de vida das pessoas com deficiência. / [en] Developing and building a prosthesis or orthosis with easy adaptation for the user is still a major challenge in the engineering area in general. In addition, the use of electromechanical elements inserts autonomy and portability as factors of difficulty in construction. Another point is that variations in human factors, such as spasticity, muscle tone or changes resulting from diseases such as cerebral palsy or nerve damage, interfere with the construction of the device. Therefore, the construction of an orthosis is a challenging and multidisciplinary job, which involves a deep and detailed analysis from the application to the actual construction. The use of Industry 4.0 techniques to make the orthosis comfortable, lightweight, and easy to use is fundamental to this, as is the analysis and processing of biosignals and control, making sure that each step is connected and adjusted so that it functions correctly. This aims to evaluate the theoretical and experimental methods of construction and dynamic evaluation of a bio-orthosis of upper limbs using the concept of industry 4.0, digital manufacturing processes, multi-structural optimization, bio-signal processes and non-linear control techniques. This study was motivated by the advancement of the use of digital manufacturing in the field of bio-medicine, by the great challenge from the point of view of control, by the variability that these processes can have in the construction of orthoses in improving the quality of life of people with disabilities.

Lattice structures have received a lot of attention as cellular materials in recent years because of their outstanding properties, such as high strength-to-weight ratio, heat transfer, energy absorption, and capability of improving noise, vibration and harshness (NVH) behavior. This type of structure received a boost from additive manufacturing (AM) technology, which can fabricate geometries in practically any shape. Due to economic and environmental requirements, lightweight design is increasingly used in automobile and construction equipment applications. NVH behavior is a crucial issue for construction equipment. However, the conventional structures' NVH behavior is mainly decided by the mass, so silence often requires heavy systems, leading to more energy consumption and emission. Therefore, the environmental trends and the resulting economic competition have limited traditional (heavy) solutions to improve NVH behavior and make the lightweight design more difficult. Novel solutions are necessary to light the difficulty and challenge of combining NVH and lightweight requirements. In this research, topology optimization was implemented on a New Articulated Hauler Transmission (NAHT) component to balance lightweight and NVH behavior. The topology- optimized 3D model was filled by a non-homogenous lattice structure with optimal lattice density via size optimization. Lattice structure optimization is one type of topology optimization, and it is the term for describing these procedures. To fabricate the complicated lattice structure, additive manufacturing (or 3D printing) is required (after topology and lattice structure optimization). The new models were analyzed using the finite element method (FEM), and the results of the analysis were compared with those of the original models. After the comparison, positive results were obtained, demonstrating that topology and lattice optimization can be applied in the design of construction equipment components. According to the results, lattice structure optimization can create a reliable lightweight design with good NVH behavior. Furthermore, lattice structure's organization and layout have a significant impact on the overall performance. / Gitterstrukturer har fått mycket uppmärksamhet som cellulära material under de senaste åren på grund av deras enastående egenskaper, t.ex. hög hållfasthet i förhållande till vikt, värmeöverföring, energiabsorption och förmåga att förbättra buller-, vibrations- och bullerskador (NVH-beteende). Denna typ av struktur har fått ett uppsving av tekniken för additiv tillverkning (AM), som kan tillverka geometrier i praktiskt taget vilken form som helst. På grund av ekonomiska och miljömässiga krav används lättviktsdesign i allt större utsträckning inom bilindustrin och byggnadsutrustning. NVH-egenskaperna är en viktig fråga för anläggningsutrustning. De konventionella konstruktionernas NVH-beteende bestäms dock huvudsakligen av massan, vilket innebär att tystnad ofta kräver tunga system, vilket leder till ökad energiförbrukning och större utsläpp. Miljötrenderna och den ekonomiska konkurrens som följer av detta har därför begränsat de traditionella (tunga) lösningarna för att förbättra NVH-egenskaperna och gjort lättviktsdesignen svårare. Nya lösningar är nödvändiga för att lösa svårigheten och utmaningen med att kombinera NVH- och lättviktskrav. I den här forskningen genomfördes topologioptimering på en komponent för en ny ledad transportörtransmission (NAHT) för att balansera lättvikts- och NVH-beteende. Den topologioptimerade 3D-modellen fylldes med en icke-homogen gitterstruktur med optimal gittertäthet via storleksoptimering. Gitterstrukturoptimering är en typ av topologioptimering, och det är termen för att beskriva dessa förfaranden. För att tillverka den komplicerade gitterstrukturen krävs additiv tillverkning (eller 3D-utskrift) (efter topologi- och gitterstrukturoptimering). De nya modellerna analyserades med hjälp av finita elementmetoden (FEM), och resultaten av analysen jämfördes med resultaten av de ursprungliga modellerna. Efter jämförelsen erhölls positiva resultat, vilket visar att optimering av topologi och gitterstruktur kan tillämpas vid utformning av komponenter för byggutrustning. Enligt resultaten kan optimering av gitterstrukturen skapa en tillförlitlig lättviktsdesign med bra NVH-beteende. Dessutom har gitterstrukturens organisering och layout en betydande inverkan på den totala prestandan.