De nos jours, le domaine des implants est un des enjeux important pour notre civilisation pour permettre d’améliorer notre quotidien. Pour ce faire, une large offre de matériaux et de technologies existe offrant de nombreuses possibilités afin de répondre aux attentes chirurgicales. Plusieurs familles de matériaux coexistent : les polymères, les céramiques et les matériaux métalliques ainsi que différents procédés de mise en forme. Parmi ceux-ci, le procédé de micro fusion laser sur lit de poudre est un procédé prometteur permettant de réaliser des pièces de géométries complexes. C’est précisément cette technologie qui a été retenue. Pour cela, afin d’approfondir la connaissance du procédé et évaluer l’impact des paramètres sur les structures métallographiques, une orientation se tournant vers des matériaux métalliques tels que le CoCrMo et le titane T40 a été envisagée.Ainsi, les objectifs de la thèse ont été de générer un matériau possédant de bonnes caractéristiques mécaniques ainsi qu’en faciliter son intégration dans un milieu biologique (implants). Pour ce faire, une structure de porosité contrôlée (pour faciliter le développement tissulaire) avec des propriétés mécaniques adaptées aux sollicitations est nécessaire. Le premier travail effectué fut donc une recherche préliminaire afin d’approfondir la connaissance du procédé, en particulier d’un point de vue énergétique et thermique. Afin d’identifier et d’évaluer l’impact des paramètres sur le taux de porosité et donc les propriétés mécaniques de la pièce, une méthode statistique de type Taguchi a été utilisée. Au travers de cette analyse, il est apparu que 3 paramètres inhérents au procédé (la distance entre tache laser, temps d’exposition et le pas de balayage) expliquent prêt de 80% des résultats. De plus, il est mis en évidence que les propriétés mécaniques d’une structure (module de Young et résistance à la rupture) peuvent être maitrisées grâce au taux de porosité de cette dernière et permettre ainsi un rapprochement des propriétés mécaniques de l’os cortical. Pour ce faire, des caractérisations mécaniques ont donc été réalisées pour évaluer le module de Young et la résistance à la rupture des pièces avec différentes structures. Une maîtrise des propriétés peut donc être envisagée et peut même être adaptée en réalisant des structures mixtes alliant partie dense et partie poreuse. / Nowadays, the field of implants is one of the major challenges for our civilization to help improve our lives. To do this, a wide range of materials and technologies are offering many opportunities to meet the surgical needs. Several types of materials exist: polymers, ceramics and metal as well as different methods of shaping materials. Among them , the process of micro fusion laser powder bed is a promising method for producing parts with complex geometries. It is this technology that has been used. To do this, in order to deepen the knowledge of the process and evaluate the impact of parameters on the metallographic structures , guidance , turning to metallic materials such as CoCrMo and titanium T40 was considered.Thus, the objectives of the thesis were to generate a material with good mechanical properties as well as ease of integration in a biological medium ( implants) . To do this, a controlled pore structure (to facilitate tissue development ) with properties adapted to mechanical stress is required. The first work was therefore a preliminary research to deepen understanding of the process , particularly an energy and thermal point of view . To identify and assess the impact of parameters on the porosity and therefore the mechanical properties of the part , a statistical method of Taguchi type was used. Through this analysis, it appeared that three parameters inherent to the process ( the distance between laser spot exposure and no scanning time ) explain 80% loan results. Moreover, it is highlighted that the mechanical properties of a structure ( Young's modulus and tensile strength ) can be controlled through the porosity of the latter and thus permit reconciliation of the mechanical properties of cortical bone . To do this , mechanical characterizations were therefore conducted to evaluate the Young's modulus and tensile strength of parts with different structures. A control properties can be considered and can even be adapted by making composite structures combining dense part and porous part .

In composite materials, transverse shear modulus is a critical moduli parameter for designing complex composite structures. For dependable mathematical modeling of mechanical behavior of composite materials, an accurate estimate of the moduli parameters is critically important as opposed to estimates of strength parameters where underestimation may lead to a non-optimal design but still would give one a safe one. Although there are mechanical and empirical models available to find transverse shear modulus, they are based on many assumptions. In this work, the model is based on a three-dimensional elastic finite element analysis with multiple cells. To find the shear modulus, appropriate boundary conditions are applied to a three-dimensional representative volume element (RVE). To improve the accuracy of the model, multiple cells of the RVE are used and the value of the transverse shear modulus is calculated by an extrapolation technique that represents a large number of cells. Comparing the available analytical and empirical models to the finite element model from this work shows that for polymeric matrix composites, the estimate of the transverse shear modulus by Halpin-Tsai model had high credibility for lower fiber volume fractions; the Mori-Tanaka model was most accurate for the mid-range fiber volume fractions; and the Elasticity Approach model was most accurate for high fiber volume fractions. Since real-life composites have voids, this study investigated the effect of void fraction on the transverse shear modulus through design of experiment (DOE) statistical analysis. Fiber volume fraction and fiber-to-matrix Young’s moduli ratio were the other influencing parameters used. The results indicate that the fiber volume fraction is the most dominating of the three variables, making up to 96% contribution to the transverse shear modulus. The void content and fiber-to-matrix Young’s moduli ratio have negligible effects. To find how voids themselves influence the shear modulus, the transverse shear modulus was normalized with the corresponding shear modulus with a perfect composite with no voids. As expected, the void content has the largest contribution to the normalized shear modulus of 80%. The fiber volume fraction contributed 12%, and the fiber-to-matrix Young’s moduli ratio contribution was again low. Based on the results of this work, the influences and sensitivities of void content have helped in the development of accurate models for transverse shear modulus, and let us confidently study the influence of fiber-to-matrix Young’s moduli ratio, fiber volume fraction and void content on its value.

Liquid composite molding (LCM) is growing in importance alternative to traditional prepreg-autoclave methods for manufacture aerospace composites. The most significant roadblock to industry's implementation of LCM is the optimization of resin flow to ensure high quality parts. This study developed process optimization tools to foster the adaptation of LCM. The following dissertation characterized the permeability of reinforcement fabrics under various processing conditions, and investigated in-situ bubble flow with carbon fiber. The purpose of this research is to extend the understanding of LCM and push forward the state of the art via sub-studies captured in five chapters, or manuscripts. Research from these manuscripts is as follows. Chapter 3 sets the groundwork for LCM optimization by extending the current theory for assessing 3D permeability of reinforcement fabrics using an ellipsoidal point infusion experiment. The aim was to improve 3D permeability measurement accuracy for LCM processing models. This work is the first to compare solutions in the context of 75 experiments. Chapters 4 and 5 extend permeability analysis to curved and sheared geometries, typical to real-world aerostructures. Chapter 4 demonstrates a method for measurement of curvature effects on permeability with vacuum infusion. A correlation was shown between curvature (as evaluated over four radii) and effective permeability. Chapter 5 researches the shearing of reinforcement fabric (e.g. when reinforcements are draped over double curvature). The study shows that permeability actually increases for mid-range shear angles beyond the shear-locking angle, and develops a technique for obtaining the 3D permeability of sheared fabric.Chapter 6 investigates carbon fiber voids in situ. LCM optimization requires improved void monitoring for carbon fiber. It is challenging to monitor void flow in situ with carbon fiber reinforcements because of fiber opacity. The research builds upon a new automated fluorescent imaging method to monitor void flow in-situ. Results include high-resolution and high-contrast images and 230 data points for infusion velocity vs. void content data.Chapter 7 contributes to the growing interest in LCM processes for aerospace applications by providing a short cost summary of typical processes for manufacturing aerospace composite parts. Data shows that LCM is a financially wise alternative to automated fiber placement (prepreg-autoclave) manufacturing when a void content of 2-2.5% is acceptable. Work on LCM processes optimization indicates that these percentages will reduce in coming years.

Three different void content calculation techniques using optical microscopy werecompared in multiple-user trials. The three methods studied comprised of a selection,thresholding, and semi-automatic machine learning method. The techniques wereapplied to micrographs of three carbon fiber-epoxy composite plates manufacturedin-house, where one plate had reduced void content by means of debulking priorto curing. The users performed the techniques on the sets of micrographs and thestandard deviation between the users void content results were measured.The advantages of the three methods were discussed and their practical applications wereproposed. The trials showed agreement between users on what are voids and not as well asshowing that uncertainties in void content are specimen-specific and not attributed todifferent users or methods applied. All three methods showed satisfying precision incalculating void content compared to void content quality levels provided by literature.It was found that thresholding, which is the current standard method of void contentcalculation using microscopy, inhabits an unscientific bias which compromises the legitimacyof the method. The study formulates a manual selection-based method usingedge-detection selection tools intended to benchmark void content in images, as wellas proposing a route to the automation of void content analysis using microscopy. / Tre olika beräkningstekniker för kavitetshalter med hjälp av mikroskopi jämfördes genom fleranvändar-tester. De tre metoderna innefattade en selektions-metod, tröskelvärdesmetod, och en övervakad maskininlärningsmetod. Metoderna applicerades på mikrografer av tre kolfiber-epoxi kompositplattor tillverkade internt, varav en platta hade reducerad kavitetshalt genom en avbulkningsprocess innan härdning. Användarna genomförde metoderna på mikrograferna och standardavvikelsen mellan användarnas resulterande kavitetshalter mättes. För- och nackdelarna hos de tre metoderna diskuterades och deras praktiska applikationer föreslogs. Testerna visade en överensstämmelse mellan användare om vad som omfattar kaviteter och inte, samt en påvisning på att osäkerheter kring kavitetshalter är provbitberoende och inte användar- eller metodberoende. Alla tre metoder uppvisade en tillfredsställande precision i kavitethaltsberäkning jämfört med kvalitetsnivåer av kavitethalter erhållna från litteratur. Det konstaterades att tröskelvärdesmetoden, vilket är nuvarande standardmetoden för kavitethaltsberäkning med mikroskopi, innehar en bias som sätter validiteten av metoden i fråga. Studien formulerar även en manuell selektions-metod som använder selektions-verktyg för randdetektering, ämnad för att hitta referensvärden för kavitetshalter. Förslag ges även kring tillvägagångssättet till att uppnå automatiserade metoder för kavitethaltsberäkning.

The objective of this study is to characterize the properties of typically adopted drainage layer materials in VA, OK, and ID. A series of laboratory tests have been conducted to quantify the volumetric properties, permeability and mechanical properties of the laboratory-compacted asphalt treated and cement treated permeable base specimens. The modified test protocols to determine the dynamic modulus of the drainage layer materials have been provided, which can be followed to determine the dynamic modulus of the drainage layers as level 1 input in Mechanistic-Empirical (M-E) pavement design. The measured dynamic moduli have been used to calibrate the original NCHRP 1-37A model to facilitate its application on drainage layer materials for prediction of the dynamic modulus as level 2 input. The compressive strength of the cement treated permeable base mixture of different air void contents has also been quantified in laboratory. Numerical simulations are conducted to investigate the location effects and the contribution of the drainage layer as a structural component within pavement. The optimal air void content of the drainage layer is recommended for Virginia, Oklahoma and Idaho based on the laboratory-determined permeability and the predicted pavement performances during 20-year service life. / Ph. D.

El deterioro de las estructuras de concreto debido al ataque de agentes externos, es una de las problemáticas con más énfasis en el rubro de la construcción, ya que afecta directamente las propiedades de la infraestructura, dando como resultado la reducción de vida útil. Por otro lado, tenemos el incremento de construcciones cerca al litoral marítimo, sin embargo, surge la problemática de presencia de eflorescencia, desprendimiento, corrosión o manchas en el concreto, por el ataque de sulfatos presente en el agua de mar, en el suelo, y en la humedad. A lo largo de los años se ha propuestos productos como adiciones en la composición del cemento o productos no permeables para aplicar al concreto, con el fin de minimizar el impacto. Para la presente investigación se estudia la efectividad del polvo de ladrillo, como reemplazo parcial del cemento, mediante los ensayos de resistencia a la compresión, trabajabilidad en estado fresco, volumen de contenido de vacíos y permeabilidad. Se realizó pruebas con cuatro diferentes proporciones de reemplazo como es 5%, 15%, 25% y 30%, para una resistencia de f´c 300 kg/cm2. De acuerdo a los resultados, se concluyó que la muestra con reemplazo parcial de polvo de ladrillo de arcilla en 25%, demuestran resultados óptimos como mayor resistencia, además de un bajo volumen de contenido de vacíos y una permeabilidad baja. Asimismo, muestra una reducción económica de fabricación por m3 de 8.72%, en comparación a la muestra convencional. / The deterioration of concrete structures due to the attack of external agents, is one of the problems with more emphasis in the construction sector, since it directly affects the properties of the infrastructure, resulting in a reduction in useful life. On the other hand, we have the increase in constructions close to the sea coast, however, the problem of efflorescence, detachment, corrosion or stains on the concrete arises, due to the attack of sulphates present in seawater, in the soil, and in the humidity. Over the years, products such as additions in the cement composition or non-permeable products have been proposed to apply to concrete, in order to minimize the impact. For the present investigation, the effectiveness of brick dust is studied as a partial replacement for cement, through tests of compressive strength, workability in a fresh state, void content volume and permeability. Tests were carried out with four different replacement proportions such as 5%, 15%, 25% and 30%, for a resistance of f'c 300 kg / cm2. According to the results, it was concluded that the samples with partial replacement of clay brick dust in 25% demonstrate optimal results such as greater resistance, in addition to a low volume of voids content and a low permeability. Likewise, it shows an economic reduction in manufacturing of m3 of 8.72%, compared to the conventional sample. / Tesis

The aim of bachelor thesis is to gain experience with the design mixtures of asphalt concrete for very thin layers. Familiarizing with the properties of these mixtures, as porosity, water resistance and resistance to permanent deformation. Comparing detected parameters with the requirements of standard EN 13108-2 and its National Annex.