In this thesis, the relationship between the elastic modulus of PDMS and the base/agent ratio (the amount of crosslinking) is studied. Reliable macroscopic compression test instrument was developed. Preload method was applied for the nanoindentation flat punch test to develop full contact. In chapter 2, an easy instrument setup for macroscopic compression test is described. A series of PDMS samples with different base/agent ratios were tested using the macroscopic compression method. The relationship between PDMS elastic modulus and its base/agent ratio was established. In chapter 3, PDMS nanoindentation DMA tests provide stable data with different test control models. The storage modulus collected using nanoindenting DMA tests is comparable with elastic modulus collected in PDMS compression test in chapter 2. Nanoindentation experiments with flat punch were also done to test the elastic modulus of PDMS network 5:1. The adhesion force tests with different nanoindentation tips, which are Berkovich tip, conical tip and cube corner tip, show that PDMS's adhesion force is related to the sample's base/agent ratio, the nanoindentating depth and the tip's geometrical shape.

Cette thèse intervient dans le cadre du projet ANR ARMS. L'objectif est de concevoir un système robotisé multi-bras pour la découpe anatomique de muscles. Ce travail vise à développer les modèles mécaniques nécessaires à la mise en place de la stratégie de commande. Il expose le cycle de développement d'un modèle mécanique faisant intervenir la construction de modèles géométriques à partir d'images IRM, l'identification expérimentale des paramètres rhéologiques des matériaux modélisés en passant par les étapes de maillage, de paramétrage, d'implémentation et de validation de tels modèles. Il présente une nouvelle méthode de modélisation dynamique de structures intitulée modèle masse-ressort non-linéaire isotrope transverse, une méthode qui témoigne d'un comportement mécanique alliant réalisme et interactivité. Il intervient aussi dans l'identification dynamique des trajectoires de coupe robotisée en proposant de nouvelles approches de modélisation de la découpe de corps mous et en développant un nouvel algorithme basé sur le calcul de courbures. Cette thèse aborde, aussi, le problème de variabilité des muscles bovins et propose une méthode de recalage dimensionnel du modèle géométrique générique par le biais de transformations géométriques définies par optimisation multicritère d'une fonction objectif. Enfin, en vue de synchroniser le flux d'informations entre les différents modules de commande de la cellule robotisée, une combinaison de la méthode des éléments finis avec la technique de condensation statique de Guyan a permis de développer un modèle mécanique quasi-statique réduit permettant de prédire rapidement l'évolution de la trajectoire de coupe robotisée. / This PhD thesis is done within the framework of the ANR ARMS project. The global objective is to study the robotization of deboning and muscle separation in meat cutting and transformation processes applied to beef rounds. This work aims to develop the necessary mechanical models feeding the process control strategy. It outlines the development cycle of a mechanical model involving the construction of geometrical models using MRI techniques, the experimental identification of rheological parameters of materials while going through the steps of meshing, parameterization, implementation and validation of such models. It presents and tests a new way to fix the parameters of the mass-spring model whilst taking into account material anisotropy. The new approach is entitled « non-linear transversally isotropic mass-sping model » and sets the model in non-linear mechanical behavior mode which therefore increases the realism of the simulations performed. It is also involved in the dynamical estimation of the cutting guideline by proposing new approaches for soft materials cutting and by developing a new algorithm based on vision perception and curvature estimation of 3D surfacic meshes. This work addresses also the problem of muscles variability and provides a readjustement method of the generic geometrical model based on a multicriteria optimization of an objective function. Finally, in order to synchronize the information flow between the control modules of the robotic cell, a combination of the finite element method with Guyan static condensation technique allowed developing a reduced quasi-static mechanical model rapidly predicting the evolution of the cutting trajectory.

Semiconducting polymers with a conjugated backbone are important for energy storage, conversion, and biomedical field applications. The self-assembly process of these polymers in solutions depends on the polymer concentration and quality of the solvent. The electrical properties of thin films obtained from the solution phase depend on the self-assembled process. Thin films of conjugated polymer gels with percolating networks of self-assembled structures display improved electrical conductivities. In this dissertation, we studied the impact of the secondary gel matrix formed by a low molecular weight gelator, on the self-assembly of conjugated polymers, the preservation of assembled structures in dried gel films and their electrical properties. The study utilized di-Fmoc-l-Lysine gelator, to form a hybrid gel with poly(3-hexylthiophene) in chloroform. The aggregation of P3HT with the progression of gelation was captured using spectroscopic analysis. The aggregates remain in the interstitial spaces of the fibrillar microstructure of gelator. With restricted mobility and due to higher local concentration, the aggregates formed nanofibriliar structures. Microstructural data indicated the nanostructures formed a percolating network in the dried films with good bulk conductivity, despite conductive polymer content of only 20%. Conjugated polymers require a high boiling point and toxic halogenated solvents to develop gels limiting their applications. By utilizing the amphiphilic nature of the gelator, a thermoreversible gel was obtained in 1-propanol, by combining it with an isoindigo-based DA polymer, engineered with galactose side chains to improve its solubility in eco-friendly solvents. Uniform distribution of aggregated polymer increased the shear moduli of the gels. The electrical conductivity of the dried gels confirmed the existence of percolated aggregates. Additional solvent systems were explored, such as 1-propanol mixed with chloroform. Although P3HT is insoluble in 1-propanol, by adjusting chloroform and 1-propanol ratio, a stable gel was obtained. The poor solvent, 1-propanol, assists the self-assembly of P3HT, improving the electrical performance of dried hybrid gels. The findings from this study contribute to a better understanding of the self-assembly of conjugated polymers utilizing molecular gels as templates. It provides a framework for obtaining semiconducting gels for applications in the biomedical field, and for large-scale fabrication of optoelectronic devices. Semiconducting polymers with a conjugated backbone are important for energy storage, conversion, and biomedical field applications. The self-assembly process of these polymers in solutions depends on the polymer concentration and quality of the solvent. The electrical properties of thin films obtained from the solution phase depend on the self-assembled process. Thin films of conjugated polymer gels with percolating networks of self-assembled structures display improved electrical conductivities. In this dissertation, we studied the impact of the secondary gel matrix formed by a low molecular weight gelator, on the self-assembly of conjugated polymers, the preservation of assembled structures in dried gel films and their electrical properties. The study utilized di-Fmoc-l-Lysine gelator, to form a hybrid gel with poly(3-hexylthiophene) in chloroform. The aggregation of P3HT with the progression of gelation was captured using spectroscopic analysis. The aggregates remain in the interstitial spaces of the fibrillar microstructure of gelator. With restricted mobility and due to higher local concentration, the aggregates formed nanofibriliar structures. Microstructural data indicated the nanostructures formed a percolating network in the dried films with good bulk conductivity, despite conductive polymer content of only 20%. Conjugated polymers require a high boiling point and toxic halogenated solvents to develop gels limiting their applications. By utilizing the amphiphilic nature of the gelator, a thermoreversible gel was obtained in 1-propanol, by combining it with an isoindigo-based DA polymer, engineered with galactose side chains to improve its solubility in eco-friendly solvents. Uniform distribution of aggregated polymer increased the shear moduli of the gels. The electrical conductivity of the dried gels confirmed the existence of percolated aggregates. Additional solvent systems were explored, such as 1-propanol mixed with chloroform. Although P3HT is insoluble in 1-propanol, by adjusting chloroform and 1-propanol ratio, a stable gel was obtained. The poor solvent, 1-propanol, assists the self-assembly of P3HT, improving the electrical performance of dried hybrid gels. The findings from this study contribute to a better understanding of the self-assembly of conjugated polymers utilizing molecular gels as templates. It provides a framework for obtaining semiconducting gels for applications in the biomedical field, and for large-scale fabrication of optoelectronic devices.

No description available.

Depuis plusieurs décennies, l’évaluation des armes à létalité réduite (ALR) et des gilets pare-balles suscite l’intérêt majeur des forces de l’ordre autour du globe. En effet, ces armes présumées à létalité réduite ou non létales sont tenues d’occasionner uniquement une douleur suffisamment importante à un individu afin d’assurer sa neutralisation. Les gilets pare-balles, quant à eux, doivent garantir un certain niveau de protection pour réduire le risque de traumatismes lié à leur déformation dynamique. Le Centre de Recherche, d’Expertise et d’appui Logistique (CREL) du Ministère de l’Intérieur français a ainsi pour objectif le développement d’un outil de prédiction du risque lésionnel thoracique lors d’impacts balistiques non pénétrants. Cela permettrait alors d’évaluer les performances des ALR et des gilets pare-balles avant leur déploiement en théâtre d’opérations. Plus précisément, cette méthode doit uniquement être fondée sur la mesure directe du processus dynamique de déformation d’un bloc de gel synthétique soumis à un impact balistique. Pour répondre à ce besoin, l’approche numérique est considérée dans ces travaux de thèse par l’emploi du mannequin numérique du thorax humain HUByx comme un outil intermédiaire permettant la détermination de fonctions de transfert entre les mesures expérimentales sur un bloc de gel et le risque lésionnel. La reproduction de conditions d’impact réelles sur HUByx nécessite la caractérisation et la modélisation de projectiles ALR ainsi que de projectiles d’armes à feu et de gilets pare-balles. Elles reposent sur une procédure d’identification par méthode inverse appliquée à l’essai de Taylor pour la modélisation des ALR et à l’essai du cône dynamique d’enfoncement sur le bloc de gel pour celle du couple projectile/gilet pare-balles. Des travaux sont dédiés à la caractérisation mécanique et à la modélisation du gel synthétique sous sollicitations dynamiques. Enfin, une approche statistique basée sur des analyses de corrélation est introduite exploitant à la fois les mesures expérimentales, les données numériques ainsi que les rapports de cas de la littérature. Une cartographie du thorax associée au risque de fractures costales est établie et est uniquement fonction d’une mesure expérimentale. / For decades, the assessment of less-lethal weapons (LLW) and bulletproof vests has generated major interest from law enforcement agencies around the world. Indeed, these presumed less-lethal or non-lethal weapons are required to cause only significant pain to an individual to ensure their neutralization. Bulletproof vests, in turn, must provide a certain level of protection to reduce the risk of trauma related to their dynamic deformation. The Center for Research, Expertise and Logistics Support (CREL) of the French Ministry of the Interior aims to develop a tool to predict thoracic injury risk during non-penetrating ballistic impacts. It would therefore be possible to evaluate the performance of LLW and bulletproof vests before their deployment in operations. More precisely, this method must only be based on the direct measurement of the dynamic process of deformation of a synthetic gel block subjected to a ballistic impact. To address that issue, the numerical approach is considered in this thesis by the use of the human thorax dummy HUByx as an intermediate tool for the determination of transfer functions between experimental metrics on a gel block and the risk of injury. The reproduction of real impact conditions on HUByx thus requires the characterization and modeling of less-lethal projectiles as well as projectiles of firearms and bulletproof vests. They rely on an inverse method identification procedure applied to the Taylor test for modeling LLW and on the analysis of blunt impacts on the gel block for projectiles/bulletproof vests. Work is then dedicated to the mechanical characterization and modeling of the synthetic gel under dynamic loadings. Finally, a statistical approach based on correlation analyses is introduced using both experimental measurements, numerical data as well as case reports from the literature. A thorax mapping associated with the risk of rib fractures is established and only depends on an experimental metric.

<p>    </p> <p>Additive manufacturing (or 3D printing) is one of the manufacturing processes which is currently being explored for its applicability under space boundary conditions, also known as in-space manufacturing. The space boundary conditions specifically affect material properties which in turn affect the printability of materials in space. Printing of soft materials in space is a novel application and the intent of this research was to print the softest of materials: edible materials, as a case study. 3D food printing is a novel food delivery method of using food products to either reproduce as a more aesthetically pleasing product or to print more nutrient-diverse foods. Launch of payload carrier and the boundary conditions of low Earth orbit including a vacuum environment, microgravity, temperature fluctuations, etc. These conditions make printing difficult, and my thesis is to overcome the boundary conditions (except microgravity) using a 3D soft material printer operating within a CubeSat. A CubeSat is a small satellite usually launched as an auxiliary payload used for basic Earth observation and radio communication. The printer must be able to survive launch and operation conditions, print within a simulated space environment, and adhere to the American Society for Testing and Materials (ASTM) specific definition of additive manufacturing. The 3D soft material printer was designed, fabricated, and tested using space and CubeSat boundary conditions for determining optimal design. Testing conditions including: (1) printing under Earth conditions showing it follows ASTM standards, (2) surviving NASA standards for vibration testing for microsatellites under launch conditions, (3) completing a print under a vacuum setting. The results of the testing would prove a small microsatellite could print in the vacuum of space and survive launch parameters. Further work would provide insight into the design of food printers being readily available in smaller sizes and its operability in microgravity condition. </p>