Neue additive Fertigungsverfahren erzeugen hochkomplexe Strukturen deren strukturmechanische Eigenschaften bisher nicht vorhersagbar waren. Mit einem neuen Ansatz wird ohne Vernetzung wie sie in der FEM benötigt wird, eine Simulation des strukturmechanischen Verhaltens möglich. Erste Untersuchungen an bisher unvorstellbar komplexen Modellen zeigen eine hervorragende Performance, die gerade im Umfeld von typischen Gitterstrukturen der 3D-Druckverfahren einsetzbar sind und darüber weit hinausgehen. In diesem Vortrag wird anhand von Beispielen der hohe Wirkungsgrad der Software External aufgezeigt, der so in der FEM nicht möglich ist.

Metallic biomaterials have an essential portion of uses in biomedical applications. Their properties can be tuned by many factors resulting in their process tuneability. Among metallic biomaterials for biomedical and specifically orthopedic applications, titanium and its alloys exhibit the most suitable characteristics as compared to stainless steels and Co-Cr alloys because of their high biocompatibility, specific strength (strength to density ratio), and corrosion resistance. According to their phase constitution, Ti-alloys are classified into three main groups, namely alpha, beta, and alpha+beta alloys. Depending on the degree of alloying and thermomechanical processing path, it is possible to tune the balance of α and β phases, which permits to tailor properties like strength, toughness, and fatigue resistance. (alpha+beta) Ti alloys, especially Ti-6Al-4V, are widely used alloys in biomedical applications; however, they have some drawbacks like the presence of toxic elements i.e., V and relatively high elastic modulus to that of bones. In view of the lower elastic modulus of body center cubic beta phase (50GPa<100GPa) compared to the alpha+beta, as well as due to their good mechanical properties, excellent corrosion resistance, and biocompatibility, beta-Ti alloys have been recently proposed as a valid alternative to alpha+beta ones. The growing interest in additive manufacturing (AM) techniques opens new and very interesting perspectives to the production of biomedical prosthetic implants. AM will prospectively allow implant customization to the patient and produce it on demand, with large savings on times and costs. Moreover, AM is gaining increasing interest due to the possibility of producing orthopedic implants with functionally graded open-cell porous metals. The main advantages of porous materials are the reduction of the elastic modulus mismatch between bone and implant alloy reducing the stress shielding effect and improving implant morphology providing biological anchorage for tissue in-growth. In this scenario, the first goal of the present PhD thesis work was to identify a high-performance β-Ti alloy formulation suitable to Laser-Powder Bed Fusion (L-PBF) additive manufacturing. In particular, it explores the potential use of a β-metastable Ti alloy, namely Ti-15Mo-2.7Nb-3Al-0.2Si (Beta Ti21S, 21 wt.% of alloying additions, including Silicon) for biomedical applications. Through microstructural, mechanical, and cytotoxicity analyses, it could be shown that this alloy grade exhibits i) an unprecedented ultra-low elastic modulus, ii) improved cytocompatibility due to the lack of Vanadium, and iii) no martensitic transformation responsible for hard and brittle solidification structures. A second goal was to assess the manufacturability of metamaterials made of β-Ti21S via L-PBF. For this purpose, cubic cellular lattice structures of different unit cell sizes (and therefore different strut thickness) have been fabricated and characterized through microstructural analysis using different techniques, and computed tomography combined with linear elastic finite element simulations to identify the minimum cell size that can be printed with adequate dimensional and geometrical accuracy. Samples of the selected unit cell size were also tested to determine their static and fatigue properties. The main results show that i) the suitable manufacturing quality is obtained for strut thickness above 0.5 mm, ii) the mechanical tests place the present cellular structures among the best stretching dominated cellular lattice materials investigated to date in the literature, and iii) the fatigue tests showed a normalized fatigue strength at 107 cycles of close to 0.8, similar to cubic lattices made of Ti-6Al-4V, and higher than most cellular structures in the literature. In the last part of the thesis, a more complex octet truss structure was fabricated in the manufacturable cell size, and its mechanical properties were investigated. The octet truss topology can be beneficial both in terms of mechanical properties and biocompatibility by providing the different types of porosity suitable for bone in-growth.

Wikipedia umschreibt die Topologieoptimierung als ein computerbasiertes Berechnungsverfahren, durch welches eine günstige Grundgestalt (Topologie) für Bauteile unter mechanischer Belastung ermittelt werden kann. Durch die Verwendung von 3D-Druck-Verfahren wird die Gestaltung der Komponenten revolutioniert, weil diese nicht mehr abhängig vom Fertigungsverfahren sind. Dabei werden auch optimale Gitterstrukturen innerhalb der Komponenten immer wichtiger. Diese neuen Herausforderungen können im Creo Umfeld mit ProTopCI (Hersteller CAESS, PTC Partner Advantage, Silver) elegant gelöst werden. Im Vortrag (mit Live-Demonstration) werden die neuen Möglichkeiten dieser innovativen Lösung beleuchtet: Modellerzeugung in Creo Simulate (FEM-Mode): - Verschiedene Lastfälle, - Kontakte, - Schraubenverbindungen, - CAD-Geometrie, - zu optimierende Bereiche, ... Technologische Randbedingungen zur Berücksichtigung des Fertigungsverfahren Innovatives Erzeugen/Optimieren der Gitterstrukturen Glätten, Exportieren der optimierten Geometrie

Durch die Verwendung von 3D-Druck-Verfahren wird die Gestaltung der Komponenten revolutioniert, weil die Form nicht mehr abhängig vom Fertigungsverfahren ist. Dabei werden auch optimale Gitterstrukturen innerhalb der Komponenten immer wichtiger. Diese Stützstrukturen können in Creo Parametric 4.0 mit dem neuen «Lattice-Feature» modelliert und Creo Simulate analysiert werden. Parallel dazu kann man mit ProTopCI (Hersteller CAESS, PTC Partner Advantage, Silver) eine Topologieoptimierung mit Stützstrukturen durchführen. Der Vortrag beleuchtet die Unterschiede dieser 2 Methoden.

Additive technology (AT) is increasingly used to design unique parts, mainly due to the ability to produce complex structures such as lattice structures. However, this also includes the need to modify the process parameters or the production strategy of the AT, which is usually set to produce volume geometry. Using samples corresponding to the geometries of the lattice structures, the exact input values were measured, which were used to design the SLM (Selective laser melting) production process using a contour strategy. Thanks to this, vertical and angled (35.26°) struts with low porosity (up to 0.2 %), low surface roughness and high dimensional accuracy were produced. Porosity was measured on µCT, surface roughness and dimensional accuracy were measured on STL data. The results show that if the parameters of the SLM process are set correctly, it is possible to produce struts with low porosity and surface roughness using different combinations of laser power and scanning speed. The above findings were used in the creation of script that allow the selection of suitable process parameters to produce lattice structures.

This diploma thesis deals with development and design modifications of tire mould segment which will be batch produced by additive technology Selective Laser Melting. Material for its production is maraging steel 1.2709. Lattice structure was used inside the segment construction. The geometry of the lattice cell was chose based on two main factors – eliminating production costs and providing sufficient stiffness. Strength of the segment was calculated by FEM. The functional sample was made and its distortion was analyzed by optical digitalization.

The subject of this master’s thesis was desingn and assessments the connection of two buildings by footbridge corridor. The structure was designed as a lattice structure without verticals. Construction is stored on two pillars lattice design. Cladding footbridge was cosidered by glazing. Construction is freestanding and doesn’t load bordering adjacent buildings.

This thesis is about linear random number generators with a large integer modulus. It is essential to be able to check that a generator has good properties in Monte-Carlo simulation. The generator family studied here produces points that possess a well known lattice structure that can be studied to assess the uniformity of these generators. The present work is motivated by the update of the LatMRG software which studies the lattice structure of the aforementioned generators. This thesis first presents the different types of generators the software considers. It explains how they can be used to produce random numbers and how to study their period length. It then presents equivalences between some members of this family that are used to simplify LatMRG. It then covers the lattice structure. The thesis describes what it is and how to characterize it. It describes the characterization of the lattice structure for the considered generators. From that, it presents a few algorithms that extract information on the uniformity of generators. At last, the thesis describes the LatMRG software. LatMRG contains both an executable program and a library. The thesis presents both their purpose and their functionalities. It describes upgrades of the software that aim to simplify its usage. Along with the software description are a few examples that serve to illustrate the flexibility and future research avenues. / Ce mémoire s’intéresse au générateurs de nombres aléatoires linéaires modulo un grand entier. Vérifier qu’un générateur possède de bonnes propriétés théoriques est essentiel pour la simulation Monte-Carlo. La famille de générateurs dont il est question produit des points possédant une structure de réseau bien connue pouvant être étudiée pour vérifier l’uniformité de ces générateurs. Le présent travail est motivé par la mise à jour du logiciel LatMRG qui permet d’étudier la structure de réseau de tels générateurs. Ce mémoire présente d’abord les types de générateurs qui sont considérés par le logiciel. Il explique comment ils peuvent être utilisés pour produire des nombres et comment étudier la longueur de leur période. Il présente ensuite des équivalences entre certains membres de la famille dont l’utilisation permet de simplifier le travail dans LatMRG. Il couvre ensuite la structure de réseau. En plus de décrire en quoi elle consiste, il explique comment la caractériser. On décrit une caractérisation de cette structure pour les générateur considérés. À partir de cela, on présente quelques algorithmes permettant d’extraire de l’information sur l’uniformité des générateurs. Le mémoire fait ensuite la description du logiciel LatMRG. LatMRG contient un programme exécutable et une librairie. Ce mémoire présente leur raison d’être et décrit leurs fonctionnalités. Il décrit aussi diverses améliorations qui ont été faites au logiciel avec pour objectif principal de simplifier son utilisation. La description du logiciel s’accompagne de quelques exemples illustrant sa flexibilité et des voies de recherche intéressantes.

This thesis deals with the use of the electronic measuring systems for monitoring structures. The first part of this work is focused on mapping the available measuring systems for monitoring deformations and strains, from the point of their measurement accuracy, the real advantages and disadvantages, including examples of monitoring of constructions. In the second part were selected measuring systems for monitoring strains and deflection interest structure. Subsequently, the measuring system with online recording into the tested roof structure was installed and the loading test was performed. Obtained data were compared with other two independent measurements. In the last part of the thesis, the measured values of each independent measurements were compared together, and with the values calculated from the mathematical model. The achieved results show that the installed monitoring system is capable to reliably measure deformation of the structure in real time and thus to warn the building administrator against the potential danger in advance.

Разработаны рекомендации, позволяющие достоверно оценить воздействие ветровой нагрузки на пространственные решетчатые конструкции. Сформулирована гипотеза о том, что расхождения значений коэффициента использования сечения элемента конструкции при различных вариантах задания ветровой нагрузки могут достигать 20%. / Recommendations have been developed to reliably assess the impact of wind load on spatial lattice structures. The hypothesis is formulated that the discrepancies in the values of the coefficient of use of the section of the structural element with different options for setting the wind load can reach 20%.