Metal Additive Manufacturing (AM) technologies in particular powder bed fusion processes such as Selective Laser Melting (SLM) and Direct Metal Laser Sintering (DMLS) are capable of producing a fully-dense metal components directly from computer-aided design (CAD) model without the need of tooling. This unique capability offered by metal AM has allowed the manufacture of inter-connected lattice structures from metallic materials for different applications including, medical implants and aerospace lightweight components. Despite the many promising design freedoms, metal AM still faces some major technical and design barriers in building complex structures with overhang geometries. Any overhang geometry which exceeds the minimum allowable build angle must be supported. The function of support structure is to prevent the newly melted layer from curling due to thermal stresses by anchoring it in place. External support structures are usually removed from the part after the build; however, internal support structures are difficult or impossible to remove. These limitations are in contrast to what is perceived by designers as metal AM being able to generate all conceivable geometries. Because support structures consume expensive raw materials, use a considerable amount of laser consolidation energy, there is considerable interest in design optimisation of support structure to minimize the build time, energy, and material consumption. Similarly there is growing demand of developing more advanced and lightweight cellular structures which are self-supporting and manufacturable in wider range of cell sizes and volume fractions using metal AM. The main focuses of this research is to tackle the process limitation in metal AM and promote design freedom through advanced self-supporting and low-density Triply Periodic Minimal Surface (TPMS) cellular structures. Low density uniform, and graded, cellular structures have been developed for metal AM processes. This work presents comprehensive experimental test conducted in SLM and DMLS processes using different TPMS cell topologies and materials. This research has contributed to new knowledge in understanding the manufacturability and mechanical behaviour of TPMS cellular structures with varying cell sizes, orientations and volume fractions. The new support structure method will address the saving of material (via low volume cellular structures and easy removal of powder) and saving of energy (via reduced build-time).

The thesis focuses on exploring the sub-grain structure in stainless steel 316L prepared by additive manufacturing (AM). Two powder-bed based AM methods are involved: selective laser melting (SLM) and electron beam melting (EBM). It is already known that AM 316L has heterogeneous property and hierarchy structure: micro-sized melt pools, micro-sized grains, nano-sized sub-grain structure and nano-sized inclusions. Yet, the relation among these structures and their influence on mechanical properties have not been clearly revealed so far. Melt pool boundaries having lower amount of sub-grain segregated network structures (Cellular structure) are weaker compared to the base material. Compared with cell boundaries, grain boundaries have less influence on strength but are still important for ductility. Cell boundaries strengthen the material without losing ductility as revealed by mechanical tests. Cellular structure can be continuous across the melt pool boundaries, low angle sub-grain boundaries, but not grain boundaries. Based on the above understanding, AM process parameters were adjusted to achieve customized mechanical properties. Comprehensive characterization were carried out to investigate the density, composition, microstructure, phase, magnetic permeability, tensile property, Charpy impact property, and fatigue property of both SLM and EBM SS316L at room temperature and at elevated temperatures (250°C and 400°C). In general, SLM SS316L has better strength while EBM SS316L has better ductility due to the different process conditions. Improved cell connection between melt pools were achieved by rotating 45° scanning direction between each layer compared to rotating 90°. Superior mechanical properties (yield strength 552 MPa and elongation 83%) were achieved in SLM SS316L fabricated with 20 µm layer thickness and tested in the building direction. Y2O3 added oxide dispersed strengthening steel (ODSS) were also prepared by SLM to further improve its performance at elevated temperatures. Slightly improved strength and ductility (yield strength 574 MPa and elongation 90%) were obtained on 0.3%Y2O3-ODSS with evenly dispersed nanoparticles (20 nm). The strength drops slightly  but ductility drops dramatically at elevated temperatures. Fractographic analysis results revealed that the coalescence of nano-voids is hindered at room temperature but not at elevated temperatures. The achieved promising properties in large AM specimens assure its potential application in nuclear fusion. For the first time, ITER first wall panel parts with complex inner pipe structure were successfully fabricated by both SLM and EBM which gives great confidence to application of AM in nuclear industry. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Manuscript.</p>

En industrie alimentaire et notamment dans le domaine des produits céréaliers, les ingrédients utilisés et les procédés associés ont des impacts sur les réactions chimiques des constituants ainsi que sur la structure des produits fabriqués. Les réactions peuvent avoir des impacts positifs (arômes, couleur) ou négatifs (développement de composés néoformés potentiellement toxiques). Bien que très étudiées dans des systèmes simplifiés, une meilleure connaissance et maitrise des réactions dans des conditions plus réalistes permettrait de mieux piloter la qualité des produits et de favoriser la balance bénéfices/risques. L’objectif de ce travail était de rendre possible l'étude des réactions dans un milieu solide, certes, simplifié, mais maîtrisé en composition et structure, et fidèle aux procédés de fabrication et à la structure à des produits réels. La génoise a été choisie comme produit de référence.La première étape a consisté à développer un produit modèle constituant une base d’étude de la réactivité. Pour cela, une étude des fonctionnalités apportées par chaque ingrédient à chaque étape du procédé de fabrication a permis d’identifier les dérivés de cellulose comme candidats intéressants pour remplacer les ingrédients réactifs (oeuf, sucre et protéines de la farine). Une étude multiéchelles a permis de mieux comprendre l’impact des principales propriétés apportées par les dérivés de cellulose (viscosité à froid, stabilisation des interfaces, gélification à chaud) sur la structuration du produit. Enfin, le produit modèle a été validé comme étant non-réactif vis-à-vis de la réaction de Maillard et de caramélisation.Dans une seconde étape, des composés réactifs (glucose, leucine) ont été réintroduits dans le produit modèle et un suivi cinétique de marqueurs de la réactivité dans les vapeurs et dans le produit a été réalisé au cours de la cuisson. Ainsi, l’enrichissement du modèle en glucose + leucine a permis de suivre le développement de composés typiques de la réaction de Maillard (aldéhydes de Strecker et pyrazines), qui n’apparaissent pas dans le cas où le produit n’est enrichi qu’en glucose, où seuls les composés issus de la caramélisation ont été identifiés. De plus, la modification des conditions de cuisson (température, convection) a permis de mettre en évidence l’impact des transferts thermiques et du séchage sur les voies réactionnelles. Ces résultats ouvrent ainsi la voie à de futures études cinétiques, couplant expérimentation systématique et modélisation. / In the food industry and notably in the field of cereal products, the type of ingredients used and their associated processes have several effects on the structure of the products and on the chemical reactions occurring during the manufacturing process. These reactions could have positive impacts (aroma, color) as well as negative outcomes (formation of potentially toxic compounds). Although being thoroughly studied in model systems, a better understanding of reactions in more realistic conditions would allow to improve the quality of the products. The aim of this work was to enable the study of chemical reactions occurring in a simplified solid system where the composition and structure were controlled while remaining representative regarding the conditions of the processes and the structure of the real product. Sponge cake was chosen as the product of reference.The first step consisted in developing a model product constituting a basis for studying the reactivity. In this regard, a study on new functionalities brought by each ingredient during each step of the manufacture process allowed to identify the cellulose derivatives as candidates to replace the reactive ingredients (eggs, sugar and wheat flour proteins). A multi-scale study allowed to better understand the impact of the main properties brought by the cellulose derivatives (viscosity at cold temperature, interface stabilization, gelation at high temperature) on the structure of the product. Finally, the model product was validated as a non-reactive media regarding the Maillard reaction and the caramelization.In a second step, reactive compounds (glucose and leucine) were placed in the model product and a kinetic monitoring on reaction markers was set up in the vapors and in the matrix during the baking. Thus, the addition of glucose and leucine in the model allowed to follow the formation of typical compounds coming from the Maillard reaction (Strecker’s aldehyde and pyrazines). These compounds did not developed when the model product was only enriched in glucose, whereas compounds generated by the caramelization reaction were identified. Moreover, changes in baking conditions (temperature, convection) allowed to emphasize the impact of heat transfer and drying on reaction pathways. These results pave the way of future kinetic studies, coupling systemic experiment and reaction modelling.

The subject of the study is a titanium implant. The research method consists in the approximate solution of the boundary value problem by the finite element method in the ABAQUS software module. A patent and literature search in the field of application of additive technologies in the production of implants. The first section presents the results of the review. Were considered methods of additive manufacturing and methods of testing porous materials, the results are described in the second section. A description of the test for precipitation of a porous implant and a finite element simulation of the process of precipitation of cellular material have been carried out. As a result, the distribution scheme of the parameters of the stress-strain state was constructed, which allows estimating dangerous sections from the standpoint of structural failure. The obtained data can be applied in building the architecture of a set of unit cells with a description of the stress-strain state. / Предметом исследования является титановый имплантат. Метод исследования состоит в приближенном решении краевой задачи методом конечных элементов в программном модуле ABAQUS. Проведен патентно-литературный поиск в области применения аддитивных технологий в производстве имплантатов. В первом разделе представлены результаты обзора. Были рассмотрены методы аддитивного производства и способы испытания пористых материалов, результаты описаны во втором разделе. Проведено описание испытания на осадку пористого имплантата и конечно-элементное моделирование процесса осадки ячеистого материала. В результате чего была построена схема распределения параметров напряженно-деформированного состояния, которая позволяет оценить опасные сечения с позиции разрушения конструкции. Полученные данные могут быть применены в построении архитектуры набора элементарных ячеек с описанием напряженно-деформированного состояния.

Making gradient in the microstructure of metals is proven to be a superior method for improving their mechanical properties. In this research, we 3D print, characterize and evaluate the mechanical properties of 316L Stainless Steel with a gradient in their microstructure. During 3D printing, the gradient in the microstructure is created by tailoring the processing parameters (hatch spacing, scanning speed, and laser power and scanning speed) of the Selective Laser Melting (SLM). The Materials with Graded Microstructure (MGMs) are characterized by optical and scanning electron microscopy (SEM). Image processing framework is utilized to reveal the distribution of cells and melt pools shapes and sizes in the volume of the material when the processing parameters change. It is shown that the laser power, scanning speed and the hatch spacing have a more significant effect on the size and shape of cells and melt pools compared to the speed. Multiple Dog bones are 3D printed with a microstructure that has smaller features (cells and melt polls) at the edges of the structure compared to the center. Tensile and fatigue tests are performed and compared for samples with constant and graded microstructures. / Master of Science / The mechanical performance of Selective Laser Melting (SLM) fabricated materials is an important topic in research. Strengthening the performance of these materials can be achieved through implementing a gradient within the microstructure, referred to as Materials with Graded Microstructure (MGMs). A complicated microstructure can weaken the microstructure, and this can be resolved by optimizing the microstructure during SLM 3D printing, in which the processing parameters are tailored. In this study, the mechanical properties of these MGMs were characterized and evaluated. The gradient in these materials were created by modifying SLM process parameters (scanning speed, hatch spacing, and laser power and scanning speed) during the build. Optical and scanning electron microscopy (SEM) was used to characterize these the microstructure of these MGMs, and image processing was used to examine the distribution of cells and melt pools characteristics throughout the region where the processing parameters changed. This investigation shows that laser power, scanning speed, and hatch spacing have a direct effect on the size and shape of the cells and melt pools, compared to scanning speed, which shows an effect on melt pools. Dog bone structures are 3-D printed with a graded microstructure that has small cells and melt pools at the edges, compared to the center, by changing the laser power and scanning speed. Tensile and fatigue analysis are performed and compared for samples with constant and graded microstructures, which reveal that the mechanical properties of the MGMs perform similar to the parameter at the edges, but differently in fracture mechanics.

Cette thèse, proposée dans le cadre du projet W2P1-DECOL (SAS PIVERT), financée par le ministère de l’enseignement supérieur est consacrée à l’étude d’un problème inverse de pressage des matériaux biologiques à structure cellulaire. Le but est d’identifier connaissant les mesures du flux d’huile sortant, le coefficient de consolidation du gâteau de pressage et l’inverse du temps caractéristique de consolidation sur deux niveaux : au niveau de la graine de colza et au niveau du gâteau de pressage. Dans un premier temps, nous présentons un système d’équations paraboliques modélisant le problème de pressage des matériaux biologiques à structure cellulaire, il découle de l’équation de continuité de la loi de Darcy et d’autres hypothèses simplificatrices. Puis l’analyse théorique et numérique du modèle direct est faite dans le cas linéaire. Enfin la méthode des différences finies est utilisée pour le discrétiser. Dans un second temps, nous introduisons le problème inverse du pressage où l’étude de l’identifiabilité de ce problème est résolue par une méthode spectrale. Par la suite, nous nous intéressons à l’étude de stabilité lipschitzienne locale et globale. De plus une estimation de stabilité lipschitzienne globale, pour le problème inverse de paramètres, dans le cas du système d’équations paraboliques, à partir des mesures sur ]0,T[ est établie. Enfin l’identification des paramètres est résolue par deux méthodes, l’une basée sur l’adaptation de la méthode algébrique et l’autre formulée comme la minimisation au sens des moindres carrés d’une fonctionnelle évaluant l’écart entre les mesures et les résultats du modèle direct, la résolution de ce problème inverse se fait en utilisant un algorithme itératif BFGS, l’algorithme est validé puis testé numériquement dans le cas des graines de colza, en utilisant des mesures synthétiques. Il donne des résultats très satisfaisants, malgré les difficultés rencontrés à manipuler et exploiter les données expérimentales. / This thesis, proposed in the framework of the W2P1-DECOL project (SAS PIVERT) and funded by the Ministry of Higher Education, is devoted to the study an inverse problem of pressing biological materials with a cellular structure. The aim is to identify, of the outgoing oil flow, the coefficient of consolidation of the pressing cake and the inverse of the characteristic time of consolidation on two levels : at the level of the rapeseed and at the level of the pressing cake. First, we present a system of parabolic equations modeling the pressing problem of biological materials with cellular structure; it follows from the continuity equation of Darcy’s law and other simplifying hypotheses. Then a theoretical and numerical analysis of a direct model is made in the linear case. Finally the finite difference method is usedt o discretize it. In a second step, we introduce the inverse problem of the pressing where the study of the identifiability of this problem is solved by a spectral method. Later we are interested in the study of local and global Lipschitizian stability. Moreover, global Lipschitz stability estimate for the inverse problem of parameters in the case of the system of parabolic equations from the measures on ]0,T[ is established. Finally, the identification of the parameters is solved by two methods; one based on the adaptation of the algebraic method and the other formulated as the minimization in the least squares sense of a functional evaluating the difference between measurements and the results of the direct model; the resolution of this inverse problem is done using an iterative algorithm BFGS, the algorithm is validated and then tested numerically in the case of rapeseeds, using synthetic measures. It gives very satisfactory results, despite the difficulties encountered in handling and exploiting the experimental data.

Im Rahmen dieser Arbeit wird ein physikalisches Modell für weichelastische EVA-Schaumstoffe entwickelt, das das mechanische Verformungsverhalten (Spannungs-Verformungs-Kurve) bei der Interaktion zwischen Sportler und Sportgerät am Beispiel eines Laufschuhs anwendungsgerecht – d.h. bei hoher Verformung und Belastungsgeschwindigkeit – kennzeichnet. Im Stand der Technik werden als Einflussfaktoren auf das mechanische Verformungsverhalten von Weichschäumen die Parameter Schaumdichte, Zellgröße bzw. Zelldurchmesser, Schaumhärte und Verformungsgeschwindigkeit ermittelt. Diese werden für die vorliegenden vier Versuchsmaterialien analysiert, wobei die letzten zwei Parameter im Modell Berücksichtigung finden. Das Modell setzt sich aus einem Matrix- und einem Gasphasenanteil zusammen. Der Matrixphasenanteil wird experimentell bei der jeweiligen Verformungsgeschwindigkeit bestimmt, wohingegen der Gasphasenanteil der in den Zellen komprimierten Luft auf einem physikalischen Zusammenhang beruht und anhand der gemessenen Schaumhärte und des Atmosphärendrucks bei der jeweiligen Verformung berechnet wird. Die Voraussetzungen für die Verwendung des Modells, zu denen inkompressible Matrixphase, Geschlossenzelligkeit und keine Querausdehnung des Schaums zählen, werden vorab umfangreich geprüft. Zusammenfassend lässt sich aussagen, dass das gewählte Modell eine gute Übereinstimmung mit den experimentell bestimmten Ergebnissen erzielt. Dies wird anhand der Mittelwertes der Differenz von experimentell ermittelten zu modellierten Daten bestimmt, für den ein Wert von 7 % berechnet wird. / The purpose of this doctoral thesis is developing a physical model for flexible foam materials (e.g. ethylene/vinyl acetate foam) characterizing the mechanical deformation behavior (stress-strain-curve) at the interaction between athlete and sports equipment (e.g. running footwear) during high deformation and high loading rate. Previous studies described various parameters influencing the mechanical deformation behavior of flexible foams: foam density, cell size / cell diameter, foam hardness and loading rate. These parameters are being analyzed for the four present foams whereof the last two parameters were considered in the model. The model consists of a matrix phase measured experimentally at required loading rate multiplied with a correction factor and a gas phase of the air compressed in the foam cells which is calculated by atmospheric pressure and foam hardness. The requirements (incompressible matrix phase, closed cells and zero Poisson ratio) for using the model are verified first of all. In conclusion, the developed model presents a good accordance with the experimental data calculated by a mean difference between experimental and modeled data of 7 %.

Le cadre général de ce travail concerne la modélisation du comportement mécanique sous impact de merlons de protection contre les chutes de blocs rocheux. Les ouvrages ciblés sont à technologie cellulaire, et sont composés de gabions à enveloppe grillagée remplis de matériaux granulaires (pierres concassées ou mélange de sable et de déchiquetas de pneus). L'absence de recommandations relatives au dimensionnement de ce type de structure de protection a conduit à la mise en place du projet ANR REMPARe couplant expérimentations in situ et modélisations numériques. Dans le cadre de ce projet, une méthode numérique innovante couplant les approches discrète et continue a été développée. Localement, la méthode des éléments discrets est employée pour conserver la précision de modélisation dans les zones fortement sollicitées proches de l'impact. Le remblai technique aval, peu sollicité, a été discrétisé par une méthode continue aux différences finies. La jonction entre ces deux zones fait l'objet d'un couplage basé sur des critères de conservation d'énergie et de condition cinématique en déplacement. Un modèle de comportement pour les gabions a été proposé et calibré à partir d'essais expérimentaux réalisés à l'échelle de la cellule. Des simulations d'impacts sur un merlon de protection prototype ont été menées puis validées par comparaison avec les mesures issues des expérimentations en vraie grandeur. Afin d'améliorer la compréhension des mécanismes engendrés, l'étude paramétrique portant sur les propriétés des matériaux et les caractéristiques d'impact a permis d'évaluer leur influence sur le mécanisme d'impact. / This study focuses on numerical modelling of the mechanical behaviour of rockfall protection structure submitted to impact. The concerned structures are constituted by cell assembly composed by wire mesh cages filled with granular material (crushed stone, mixture of sand and shredded tires). The lack of design norms led to the set up of the ANR REMPARE project which is based on real scale experiment and numerical modelling. In this project, an innovative numerical method, combining continuous and discrete approaches, has been developed. Locally, the discrete element method is used to maintain the accuracy of modelling in the highly stressed areas near the impacted zone. Downstream, the embankment, lowly stressed, is simulated by a finite difference method. The link between the two domains is ensured by a combined method which is based on energy conservation and respect of border kinematic conditions. A model for the geocells is proposed and calibrated from experimental tests carried out at the cell scale. Impacts on rockfall protection prototype are simulated and validated by comparison with measurements obtained on real scale experiments. Parametric studies on material's properties and characteristics of impact are carried out to evaluate their influence on the impact mechanisms.

Concrete’s great vulnerability against impact demonstrates significant risks of injury for workers and occupants in all building types, especially existing concrete structures in which protection measures were not originally integrated. Beside the social and economic costs directly associated with impact accidents, the reconstruction or replacement of buildings damaged by impact negatively affects the environment and resources. In response to the increasing public concern for safety and sustainability, the DFG Research Training Group GRK 2250 is formed with the core aim to develop significant improvements in the impact resistance of existing concrete buildings by applying thin strengthening layers made of innovative mineral-bonded composites. The introduction of textile-based high-performance reinforcement is highly instrumental in realizing the required functions of thin mineral-bonded strengthening layers. Novel impact-resistant 3D reinforcement is developed on the basis of the innovative 3D cellular weaving technology in this dissertation. Woven 3D cellular structures are characterized by outstanding and customizable mechanical characteristics, owning to the flexible incorporation of elements with different materials and geometries both in in-plane and out-of-plane directions. Based on a systematic and partly iterative development process, impact-resistant woven 3D cellular reinforcements containing impact-load-oriented elements and impact-appropriate material combination are successfully designed and optimized. On the one hand, a series of experiments are conducted to capture the working mechanism of woven 3D cellular structure in mineral-bonded composites loaded under impact, and to understand the effects of critical structure features. On the other hand, feasible weave patterns and effective technological solutions are worked out and implemented to enable a reliable and low-damage manufacturing process. Through a series of impact experiments, it can be strongly evidenced that the developed 3D cellular reinforcement pronouncedly enhances the load bearing capacity, ductility and energy dissipation of mineral-bonded composite undergoing impact, thus, remarkably enhances its impact resistance. The development of impact-resistant woven 3D cellular reinforcements in this dissertation introduces a completely new and unique class of textile-based reinforcement for concrete, as well as mineral-bonded composites, with numerous benefits over the presently available reinforcing structures. A major advantage of the novel 3D cellular reinforcement is the capability to activate and exploit multiple energy dissipation mechanisms using both material and structure properties, through which remarkable impact resistance can be obtained. Thanks to a high degree of versatility and flexibility in material combination and structure design, in combination with a high degree of automation and flexibility of the weaving technology, impact-resistant woven 3D cellular reinforcement that is highly customized to specific impact scenarios can be produced with a significant time and cost efficiency. Furthermore, impact-resistant woven 3D cellular reinforcements possess an integral 3D architecture that ensures a high structure stability, allowing for a speedy casting process with a high placement-accuracy. On that basis, a reasonable production cost and a stable performance of designed functions can be obtained. The successful development of impact-resistant woven 3D cellular reinforcement essentially facilitates the successful creation of high-performance mineral-bonded strengthening layers, through the use of which the impact resistance of existing concrete structures, thus, their sustainable use, significantly enhances.:1 INTRODUCTION AND MOTIVATION 1 2 LITERATURE REVIEW 7 2.1 Fundamentals of concrete and reinforced concrete 7 2.1.1 Normal concrete 7 2.1.2 Structural concrete family 10 2.1.3 Steel reinforced concrete 11 2.1.4 Concrete and reinforced concrete under impact loading 14 2.1.5 Fiber-based reinforcing materials for concrete 18 2.1.6 Fiber reinforced concrete 21 2.1.7 Textile reinforced concrete 22 2.2 Two-dimensional textile concrete reinforcements 24 2.2.1 Welded metal wire mesh 24 2.2.2 Expanded metal mesh 25 2.2.3 Woven 2D reinforcing structures 25 2.2.4 Warp knitted 2D reinforcing structures 27 2.2.5 Stitched 2D reinforcing structures 28 2.2.6 Adhesively-bonded 2D reinforcing structures 29 2.2.7 Discussion of 2D reinforcing structures 30 2.3 Three-dimensional textile concrete reinforcements 33 2.3.1 Assembled 3D reinforcing structures 33 2.3.2 Woven 3D reinforcing structures 34 2.3.3 Warp knitted 3D reinforcing structures 35 2.3.4 Stitched 3D reinforcing structures 36 2.3.5 Adhesively-bonded 3D reinforcing structures 36 2.3.6 Discussion of available 3D reinforcing structures 36 2.4 Woven 3D cellular structures 37 2.5 Conclusion based on literature review 37 3 RESEARCH AIMS AND OBJECTIVES 39 4 PRELIMINARY INVESTIGATION INTO IMPACT BEHAVIOR OF MINERAL-BONDED COMPOSITE REINFORCED WITH WOVEN 3D CELLULAR STRUCTURE 41 4.1 Introduction 41 4.2 Materials under investigation 43 4.2.1 Reinforcement - Reference woven 3D cellular structure 3DWT Ref 43 4.2.2 Matrix - Fine-grained concrete Pagel TF10 44 4.2.3 Comparing reinforcement - Warp knitted 2D structure 2D BZT2 44 4.3 Specimen labeling 45 4.4 Methodology of small-scale plate impact test 46 4.4.1 Specimen preparation 46 4.4.2 Test setup 47 4.5 Preliminary small-scale plate impact test results 47 4.6 Summary and conclusion of preliminary investigation 58 4.7 Derivation of requirements and procedure for developing impact-resistant woven 3D cellular reinforcement 59 5 DEVELOPMENT OF STRUCTURE SYSTEMATICS FOR IMPACT-RESISTANT WOVEN 3D CELLULAR REINFORCEMENT 63 5.1 Fundamentals of woven 3D cellular structure 64 5.1.1 Conventional woven structure 64 5.1.2 Elements of woven 3D cellular structure 65 5.1.3 Formation principles of woven 3D cellular structure 66 5.1.4 Variation possibilities within woven 3D cellular structure 68 5.2 Design concept of mineral-bonded strengthening layers against impact 71 5.3 Requirements for impact-resistant woven 3D cellular reinforcement 73 5.4 Two-plane woven 3D cellular reinforcements 77 5.4.1 Two-plane woven 3D cellular reinforcements with biaxial grids 77 5.4.2 Two-plane woven 3D cellular reinforcements with triaxial grids 81 5.4.3 Two-plane woven 3D cellular reinforcements with quadriaxial grids 82 5.5 Three-plane 3D cellular reinforcements 83 5.6 Material variation 85 5.6.1 Double yarns 85 5.6.2 Hybrid yarns 86 5.7 Selected impact-resistant woven 3D cellular reinforcements for realization and investigation 86 6 DEVELOPMENT OF WEAVE PATTERN FOR IMPACT-RESISTANT WOVEN 3D CELLULAR REINFORCEMENT 89 6.1 Introduction 89 6.2 Two-plane reference structure 3DWT Ref 90 6.3 Two-plane double yarn structure 3DWT DbWi 92 6.4 Three-plane structure 3DWT DbLyr 93 6.5 Two-plane pyramid structure 3DWT Pyr 95 7 DEVELOPMENT OF TECHNOLOGICAL SOLUTIONS FOR THE MANUFACTURE OF IMPACT-RESISTANT WOVEN 3D CELLULAR REINFORCEMENT 101 7.1 3D cellular weaving technology 101 7.2 Manufacture of two-plane double yarn structure 3DWT-DbWi 107 7.3 Manufacture of three-plane structure 3DWT-DbLyr 108 7.4 Manufacture of two-plane pyramid structure 3DWT-Pyr 112 8 TENSILE BEHAVIOR OF SHCC CONTAINING IMPACT-RESISTANT WOVEN 3D CELLULAR REINFORCEMENT 117 8.1 Quasi-static tension tests 117 8.1.1 Specimen preparation 117 8.1.2 Test setup 118 8.1.3 Quasi-static tension test results 119 8.2 High-speed tension tests 126 8.2.1 Specimen preparation 126 8.2.2 Test setup 126 8.2.3 High-speed tension test results 127 9 ENHANCEMENT OF IMPACT-RESISTANT WOVEN 3D CELLULAR REINFORCEMENT 131 9.1 Concept of enhanced impact-resistant 3D cellular reinforcement 131 9.2 Weave pattern development of enhanced impact-resistant reinforcement 3DWT Pyr Hyb 134 9.3 Manufacture of enhanced impact-resistant reinforcement 3DWT Pyr Hyb 136 9.3.1 Material selection 136 9.3.2 Carbon rovings impregnation 142 9.3.3 Steel wires straightening and preshaping 142 9.3.4 Weaving and realized structure 143 10 PERFORMANCE OF MINERAL-BONDED STRENGTHENING LAYER WITH IMPACT-RESISTANT WOVEN 3D CELLULAR REINFORCEMENT 147 10.1 Tensile behavior of SHCC reinforced with 3DWT Pyr Hyb 147 10.1.1 Specimen preparation 147 10.1.2 Quasi-static tension test results 148 10.1.3 Dynamic tension test results 154 10.2 Impact behavior of SHCC reinforced with 3DWT Pyr Hyb 157 10.2.1 Materials under investigation 157 10.2.2 Small-scale plate impact test results 159 10.3 SHCC reinforced with 3DWT Pyr Hyb as strengthening layer on the impacted side of concrete core 169 10.4 Summary and conclusion of the performance investigation on mineral-bonded strengthening layer reinforced with 3DWT Pyr Hyb 173 11 CONCLUSIONS AND RECOMMENDATIONS 175

Im Rahmen dieser Arbeit wird ein physikalisches Modell für weichelastische EVA-Schaumstoffe entwickelt, das das mechanische Verformungsverhalten (Spannungs-Verformungs-Kurve) bei der Interaktion zwischen Sportler und Sportgerät am Beispiel eines Laufschuhs anwendungsgerecht – d.h. bei hoher Verformung und Belastungsgeschwindigkeit – kennzeichnet. Im Stand der Technik werden als Einflussfaktoren auf das mechanische Verformungsverhalten von Weichschäumen die Parameter Schaumdichte, Zellgröße bzw. Zelldurchmesser, Schaumhärte und Verformungsgeschwindigkeit ermittelt. Diese werden für die vorliegenden vier Versuchsmaterialien analysiert, wobei die letzten zwei Parameter im Modell Berücksichtigung finden. Das Modell setzt sich aus einem Matrix- und einem Gasphasenanteil zusammen. Der Matrixphasenanteil wird experimentell bei der jeweiligen Verformungsgeschwindigkeit bestimmt, wohingegen der Gasphasenanteil der in den Zellen komprimierten Luft auf einem physikalischen Zusammenhang beruht und anhand der gemessenen Schaumhärte und des Atmosphärendrucks bei der jeweiligen Verformung berechnet wird. Die Voraussetzungen für die Verwendung des Modells, zu denen inkompressible Matrixphase, Geschlossenzelligkeit und keine Querausdehnung des Schaums zählen, werden vorab umfangreich geprüft. Zusammenfassend lässt sich aussagen, dass das gewählte Modell eine gute Übereinstimmung mit den experimentell bestimmten Ergebnissen erzielt. Dies wird anhand der Mittelwertes der Differenz von experimentell ermittelten zu modellierten Daten bestimmt, für den ein Wert von 7 % berechnet wird. / The purpose of this doctoral thesis is developing a physical model for flexible foam materials (e.g. ethylene/vinyl acetate foam) characterizing the mechanical deformation behavior (stress-strain-curve) at the interaction between athlete and sports equipment (e.g. running footwear) during high deformation and high loading rate. Previous studies described various parameters influencing the mechanical deformation behavior of flexible foams: foam density, cell size / cell diameter, foam hardness and loading rate. These parameters are being analyzed for the four present foams whereof the last two parameters were considered in the model. The model consists of a matrix phase measured experimentally at required loading rate multiplied with a correction factor and a gas phase of the air compressed in the foam cells which is calculated by atmospheric pressure and foam hardness. The requirements (incompressible matrix phase, closed cells and zero Poisson ratio) for using the model are verified first of all. In conclusion, the developed model presents a good accordance with the experimental data calculated by a mean difference between experimental and modeled data of 7 %.