The need for reliable and cost-effective testing procedures for Additive Manufacturing (AM) is growing. In this Dissertation, the development of a new computational-experimental method based on the realization of specific testing artifacts to address this need is presented. This research is focused on one of the widely utilized AM technologies, Fused Deposition Modeling (FDM), and can be extended to other AM technologies as well. In this method, testing artifacts are designed with simplified boundary conditions and computational domains that minimize uncertainties in the analyses. Testing artifacts are a combination of thin and thick cantilever structures, which allow measurement of natural frequencies, mode shapes, and dimensions as well as distortions and deformations. We apply Optical Non-Destructive Testing (ONDT) together with computational methods on the testing artifacts to predict their natural frequencies, thermal flow, mechanical properties, and distortions as a function of 3D printing parameters. The complementary application of experiments and simulations on 3D printed testing artifacts allows us to systematically investigate the density, porosity, moduli of elasticity, and Poisson’s ratios for both isotropic and orthotropic material properties to better understand relationships between these characteristics and the selected printing parameters. The method can also be adapted for distortions and residual stresses analyses. We optimally collect data using a design of experiments technique that is based on regression models, which yields statistically significant data with a reduced number of iterations. Analyses of variance of these data highlight the complexity and multifaceted effects of different process parameters and their influences on 3D printed part performance. We learned that the layer thickness is the most significant parameter that drives both density and elastic moduli. We also observed and defined the interactions among density, elastic moduli, and Poisson’s ratios with printing speed, extruder temperature, fan speed, bed temperature, and layer thickness quantitatively. This Dissertation also shows that by effectively combining ONDT and computational methods, it is possible to achieve greater understanding of the multiphysics that governs FDM. Such understanding can be used to estimate the physical and mechanical properties of 3D printed components, deliver part with improved quality, and minimize distortions and/or residual stresses to help realize functional components.

The need for reliable and cost-effective testing procedures for Additive Manufacturing (AM) is growing. In this Dissertation, the development of a new computational-experimental method based on the realization of specific testing artifacts to address this need is presented. This research is focused on one of the widely utilized AM technologies, Fused Deposition Modeling (FDM), and can be extended to other AM technologies as well. In this method, testing artifacts are designed with simplified boundary conditions and computational domains that minimize uncertainties in the analyses. Testing artifacts are a combination of thin and thick cantilever structures, which allow measurement of natural frequencies, mode shapes, and dimensions as well as distortions and deformations. We apply Optical Non-Destructive Testing (ONDT) together with computational methods on the testing artifacts to predict their natural frequencies, thermal flow, mechanical properties, and distortions as a function of 3D printing parameters. The complementary application of experiments and simulations on 3D printed testing artifacts allows us to systematically investigate the density, porosity, moduli of elasticity, and Poisson’s ratios for both isotropic and orthotropic material properties to better understand relationships between these characteristics and the selected printing parameters. The method can also be adapted for distortions and residual stresses analyses. We optimally collect data using a design of experiments technique that is based on regression models, which yields statistically significant data with a reduced number of iterations. Analyses of variance of these data highlight the complexity and multifaceted effects of different process parameters and their influences on 3D printed part performance. We learned that the layer thickness is the most significant parameter that drives both density and elastic moduli. We also observed and defined the interactions among density, elastic moduli, and Poisson’s ratios with printing speed, extruder temperature, fan speed, bed temperature, and layer thickness quantitatively. This Dissertation also shows that by effectively combining ONDT and computational methods, it is possible to achieve greater understanding of the multiphysics that governs FDM. Such understanding can be used to estimate the physical and mechanical properties of 3D printed components, deliver part with improved quality, and minimize distortions and/or residual stresses to help realize functional components.

Cette thèse porte sur l'utilisation de champs électriques pour faciliter l'élimination de l'eau coproduite avec le pétrole brut, sous la forme d'émulsions stables, lors des étapes d'extraction et de dessalement. Ce procédé, connu sous le nom d'électrocoalescence, s'appuie sur la capacité qu'ont les forces électrostatiques à promouvoir l'attraction et la coalescence de gouttelettes d'eau proches afin d'en augmenter la taille et ainsi d'en accélérer la sédimentation par gravité. Bien que les premières observations expérimentales datent déjà d'un siècle, de nombreuses zones d'ombres subsistent, notamment en ce qui concerne l'optimisation de l'efficacité des électrocoalesceurs de dernière génération. Dans ce contexte, une démarche, combinant simulation numérique multi-physique et expérimentation, a été mise en place pour étudier les phénomènes de mouvement, de déformation et d'instabilité d'interfaces eau-huile induit par la présence d'un champ électrique. La contribution la plus marquante concerne la modélisation et l'analyse de l'effet des forces électrostatiques sur le mécanisme d'amincissement du film d'huile séparant les gouttes. Les résultats numériques mettent en évidence la singularité du problème et l'inadaptabilité des modèles théoriques de lubrification classiquement adoptés pour représenter la coalescence dans les écoulements diphasiques. Une nouvelle expression asymptotique pour le calcul du temps de drainage entre les gouttelettes de l'émulsion est proposée et utilisée pour déduire un critère prédisant la probabilité d'électrocoalescence lors d'une collision dans un écoulement cisaillé. En parallèle, un dispositif sophistiqué, permettant de reproduire expérimentalement le phénomène et d'améliorer la représentativité du critère, a été construit. Enfin, en réponse à un point bloquant décelé lors de la phase de conception de ce dernier, une technique innovante d'injection à la demande de gouttes conductrices non chargées dans un liquide visqueux isolant, utilisant des impulsions électrostatiques, a été développé. / The present thesis deals with the electrostatically assisted removal of water coproduced with crude oil in the form of stable emulsions during recovery and desalting operations. This process, referred to as electrocoalescence, exploits the ability of electric forces to promote attraction and merging of adjacent water droplets to increase their size and related natural rate of sedimentation under gravity. Still, even one century after the first experimental observations, a lot of gray areas remain, particularly on the optimization of efficiency in state-of-the-art separators. To address this question, an approach combining multi-physics simulation and experiments has been used to investigate the phenomena of motion, deformation and instability of electrically influenced water-oil (droplets) interfaces. The main contribution concerns the modeling and analysis of the mechanism of oil film thinning between droplets approaching under the effect of electrostatic forces. Results from simulations highlight the strong singularity of the present problem and the inadequacy of existing theoretical lubrication models usually employed to represent coalescence events in two phase flows. For the small emulsified droplets, a new asymptotic expression for the drainage time is obtained and allows to deduce a criterion predicting the probability of electrocoalescence resulting from a shear flow induced collision. In parallel, a sophisticated setup, enabling to experimentally investigate the phenomenon and to improve the criterion relevance with regards to the actual processing conditions, has been assembled. At last and as an answer to an otherwise unfulfilled requirement defined in the design of the latter, an innovative actuation technique for the synchronous on-demand injection of two charge free conductive droplets in an insulating viscous liquid, relying on the application of a high electric field pulse, has been implemented.