Tesis por compendio / [ES] La presente tesis doctoral plantea distintas estrategias para el desarrollo y aplicación de envases activos portadores de agentes de biocontrol, con el fin de inhibir la proliferación de microorganismos como bacterias y hongos patógenos y alterantes y así, conseguir aumentar la seguridad y prolongar la vida útil de los alimentos. El desarrollo de envases activos antibacterianos se llevó a cabo incorporando bacterias ácido lácticas productoras de bacteriocinas, Lactococcus lactis y Lactobacillus sakei en diferentes matrices formadoras de películas. Previa a la preparación de las películas activas, se estudió la actividad antimicrobiana de los agentes naturales seleccionados frente a Listeria monocytogenes. Los resultados sugirieron que, a partir de una determinada concentración inicial de bacterias viables, estos microorganismos son buenos candidatos para ser utilizados como aditivos naturales en materiales de envasado de alimentos, siendo una alternativa al uso de aditivos de origen sintético. En este trabajo se observó que la viabilidad inicial de las bacterias ácido lácticas (LAB) es esencial para obtener una buena capacidad antibacteriana por lo que la optimización de la composición de las películas o recubrimientos fue crucial para su aplicación con éxito. El polímero escogido como base para hacer las películas y recubrimientos mediante la técnica de casting, fue el alcohol polivinílico, (PVOH) mezclado con diferentes proteínas, gelatina y caseinato sódico y sus versiones hidrolizadas añadidas en diferentes proporciones. En este estudio L. lactis demostró tener una mayor resistencia a la deshidratación durante la preparación y almacenamiento de las películas que L. sakei. Las películas de PVOH mezcladas con gelatina hidrolizada y caseína hidrolizada dotaron de protección a las bacterias ácido lácticas durante el secado y demostraron tener una mayor efectividad antilisteria. Por último, se varió la proporción de caseína hidrolizada obteniendo una mayor viabilidad de las bacterias en las películas prolongada en el tiempo a mayor proporción de HCas. Para desarrollar un envase activo antilisteria, se adaptaron las matrices para ser aplicadas como recubrimiento sobre ácido poliláctico (PLA) con el objetivo de desarrollar bolsas activas antilisteria para crema de setas y como separadores de lonchas de jamón cocido. Los recubrimientos demostraron tener una efectividad similar a la obtenida con las películas in vitro. Sin embargo, su eficacia disminuyó ligeramente al ser aplicadas en la crema de champiñones y el jamón cocido debido a la complejidad de las matrices alimentarias utilizadas, pero siendo una buena herramienta para, junto a otras estrategias de conservación, asegurar la salubridad de los alimentos. Se llevaron a cabo ensayos sensoriales con consumidores y se obtuvo una buena aceptación de ambos productos. Sin embargo, los consumidores percibieron una alteración del sabor debido a la generación de ácido láctico en la crema de champiñones, acidez que puede ser controlada mediante correctores de acidez sin modificar la efectividad antimicrobiana. Para desarrollar envases que aumentaran la vida útil, se trabajó para ampliar el espectro de acción de L. lactis frente a las bacterias Gram-negativas, normalmente responsables de la descomposición de los alimentos. Combinar el agente de biocontrol productor de nisina, L. lactis, con una baja concentración de ácido fítico, sustancia quelante y desestabilizadora de la membrana bacteriana, amplió el espectro antimicrobiano de L. lactis frente a las bacterias Gram-negativas obteniendo una nueva herramienta para garantizar la seguridad alimentaria y prolongar la vida útil de los alimentos. / [CA] La present tesi doctoral planteja diferents estratègies per al desenvolupament i aplicació d'envasos actius portadors d'agents de biocontrol, amb la finalitat d'inhibir la proliferació de microorganismes com a bacteris i fongs patògens i alteradors i així, aconseguir augmentar la seguretat i prolongar la vida útil dels aliments. El desenvolupament d'envasos actius antibacterians, es va dur a terme incorporant bacteris àcid làctics productores de bacteriocines, Lactococcus lactis i Lactobacillus sakei en diferents matrius formadores de pel·lícules. Prèvia a la preparació de les pel·lícules actives, es va estudiar l'activitat antimicrobiana dels agents naturals seleccionats enfront de Listeria monocytogenes. Els resultats van suggerir que, a partir d'una determinada concentració inicial de bacteris viables, aquests microorganismes són bons candidats per a ser utilitzats com a additius naturals en materials d'envasament d'aliments, sent una alternativa a l'ús d'additius d'origen sintètic. En aquest treball es va observar que la viabilitat inicial dels bacteris àcid làctics (LAB) és essencial per a obtindre una bona capacitat antibacteriana pel que l'optimització de la composició de les pel·lícules o recobriments va ser crucial per a la seua aplicació amb èxit. El polímer triat com a base per a fer les pel·lícules i recobriments mitjançant la tècnica de càsting, va ser l'alcohol polivinílic, (PVOH) mesclat amb diferents proteïnes, gelatina i caseinat sòdic i les seues versions hidrolitzades afegides en diferents proporcions. En aquest estudi L. lactis va demostrar tindre una major resistència a la deshidratació durant la preparació i emmagatzematge de les pel·lícules que L. sakei. Les pel·lícules de PVOH mesclades amb gelatina hidrolitzada i caseina hidrolitzada van dotar de protecció als bacteris àcid làctics durant l'assecat i van demostrar tindre una major efectivitat antilistèria. Finalment, es va variar la proporció de caseïna hidrolitzada obtenint una millor resposta de les pel·lícules no sols des d'un punt de vista antimicrobià, sinó també de les propietats fisicoquímiques de les pel·lícules, a major proporció de caseïna hidrolitzada.Per a desenvolupar un envàs actiu antilistèria, es van adaptar les matrius per a ser aplicades com a recobriment sobre àcid polilàctic (PLA) amb l'objectiu de desenvolupar bosses actives antilistèria per a crema de bolets i com a separadors de rodanxes de pernil cuit. Els recobriments van demostrar tindre una efectivitat similar a l'obtinguda amb les pel·lícules in vitro. No obstant això, la seua eficàcia va disminuir lleugerament en ser aplicades en la crema de xampinyons i el pernil cuit a causa de la complexitat de les matrius alimentàries utilitzades, però sent una bona eina per a, al costat d'altres estratègies de conservació, assegurar la salubritat dels aliments. Es van dur a terme assajos sensorials amb consumidors i es va obtindre una bona acceptació de tots dos productes, però una alteració del sabor degut a la generació d'àcid làctic en la crema de xampinyons corregible mitjançant correctors d'acidesa sense modificació de l'efectivitat antimicrobiana. Per a desenvolupar envasos que augmentaren la vida útil, es va treballar per a ampliar l'espectre d'acció de L. lactis enfront dels bacteris Gram-negatives, normalment responsables de la descomposició dels aliments. Combinar l'agent de biocontrol productor de nisina, L. lactis, amb una baixa concentració d'àcid fític, substància quelant i desestabilitzadora de la membrana bacteriana, va ampliar l'espectre antimicrobià de L. lactis enfront dels bacteris Gram-negatives obtenint una nova eina per a garantir la seguretat alimentària i prolongar la vida útil dels aliments. / [EN] This doctoral thesis proposes different strategies for the development and application of active packaging containing biocontrol agents, to inhibit the proliferation of microorganisms such as pathogenic and spoilage bacteria and fungi, thus increasing the safety and increasing the shelf life of foodstuffs. The development of antibacterial active packaging was carried out by incorporating bacteriocin-producing lactic acid bacteria, Lactococcus lactis and Lactobacillus sakei in different film-forming matrices. Prior to the preparation of the active films, the antimicrobial activity of the selected natural agents against Listeria monocytogenes was studied. The results suggested that, from a certain initial concentration of viable bacteria, these microorganisms are good candidates to be used as natural additives in food packaging materials, being an alternative to the use of additives of synthetic origin. In this work it was observed that the initial viability of lactic acid bacteria (LAB) is essential to obtain a good antibacterial capacity, so the optimization of the composition of the films or coatings was crucial for their successful application. The polymer chosen as a base to make the films and coatings by casting technique was polyvinyl alcohol (PVOH) mixed with different proteins, gelatin and sodium caseinate and their hydrolysed versions added in different proportions. In this study L. lactis showed higher resistance to dehydration during film preparation and storage than L. sakei. PVOH films mixed with hydrolysed gelatin and hydrolysed casein provided protection to lactic acid bacteria during drying and were shown to have a greater antilisteria effectiveness. Finally, the proportion of hydrolysed casein was varied, obtaining a better response of the films not only from an antimicrobial point of view, but also from the physicochemical properties of the films, the higher the proportion of HCas. To develop an antilisteria active packaging, the matrices were adapted to be applied as a coating on polylactic acid (PLA) with the objective of developing antilisteria active bags for cream of mushroom soup and as separator liner for cooked ham slices. The coatings showed similar effectiveness to that obtained with in vitro films. However, their effectiveness decreased slightly when applied to mushroom soup and cooked ham due to the complexity of the food matrices used, but being a good tool to, together with other preservation strategies, ensure food wholesomeness. Sensory tests were carried out with consumers and a good acceptance of both products was obtained. However, an alteration of taste due to the generation of lactic acid was detected in the mushroom soup that could be corrected by means of acidity correctors without modifying the antimicrobial effectiveness. Finally, life cycle analysis of conventional and active packaging for pastry cream was studied. In any case, despite the limitations regarding the waste product estimation, shelf-life extension through packaging innovation could significantly reduce the environmental impacts of the entire food packaging system. In the present thesis, the potential use of indigenous yeasts with antifungal capacity for the control of Penicillium expansum and the control of the mycotoxin they generate, called patulin, was also explored. In the present investigation, three new yeast strains isolated from the surface of apples were selected for their efficacy against P. expansum. The yeasts were identified as Metschnikowia pulcherrima being 3 different strains. The ability of these yeasts for patulin biodegradation was also demonstrated. Then, different studies on the viability of the yeast and its antifungal effectiveness on different films made with biopolymers naturally present in apples (pectin, cellulose ethers, and apple pomace) were carried out. / The authors acknowledge the financial support of the Spanish Ministry of Economy and Competitiveness (AGL2015-64595-R and RTI2018-093452-B-I00). / Settier Ramírez, L. (2021). Envases activos portadores de microorganismos para la bioconservación de alimentos [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/175807 / Compendio

Numerische Prozessanalysen werden heute standardmäßig zur virtuellen Prozessabsicherung der Herstellung umgeformter Blechformteile eingesetzt. Die dabei notwendige hohe Prognosegüte kann nur mit einer hinreichend präzisen Materialmodellierung realisiert werden. Ein wesentlicher Aspekt ist dabei die Modellierung des Fließverhaltens und der Werkstoffanisotropie. Zur Charakterisierung des Werkstoffverhaltens existieren zahlreiche Versuchs- und Auswertestrategien; diese werden aufgrund des hohen Versuchs- und Rechenaufwands in der industriellen Anwendung jedoch nur vereinzelt eingesetzt. Im Rahmen dieser Arbeit wird eine neuentwickelte halbanalytische Methode zur Charakterisierung von Fließortkurven sowie der Folgefließortkurven vorgestellt. Dazu wurde eine Spannungsanalyse auf Messdaten einer digitalen Bildkorrelation sowie ein Schnittlinienansatz zur Berechnung innerer Kräfte entwickelt. Durch Bilanzierung dieser inneren Schnittkräfte mit gemessenen äußeren Prüfkräften werden Parameter eines gewählten Materialmodells in einer inversen Analyse identifiziert. Die Methode zur Parameteridentifikation wurde zunächst an synthetischen und anschließend an realen Experimenten untersucht. Es wurde eine sequentielle Identifikationsstrategie aufgestellt, die an den Blechwerkstoffen DX54, DP600 sowie AA5182 untersucht wurde. Abschließend wurde die Methode mithilfe von Validierungsversuchen hinsichtlich der identifizierten Materialantworten überprüft.:Inhaltsverzeichnis I Symbolverzeichnis IV Abkürzungen und Begriffe VIII 1 Einleitung 1 2 Stand der Technik 3 2.1 Grundlagen zur Umformung von Blechwerkstoffen 3 2.1.1 Umformprozesse zur Herstellung von Blechformteilen 3 2.1.2 Anforderungen bei der Herstellung von Blechbauteilen 4 2.2 Numerische Prozessauslegung von Blechumformoperationen 5 2.2.1 Anwendung der FEM als Hilfsmittel in der Prozessauslegung 5 2.2.2 Kritische Punkte der numerischen Prozessauslegung 7 2.3 Werkstoffverhalten und Materialmodellierung 8 2.3.1 Kenngrößen zur Beschreibung großer Deformation 8 2.3.2 Grundlagen zur Beschreibung elastoplastischen Materialverhaltens 9 2.3.3 Beschreibung der Verfestigungsregel in Materialmodellen 11 2.3.4 Modellierung anisotroper Fließortkurven 12 2.3.5 Modellierung der Fließortkurvenentwicklung 18 2.3.6 Zusammenfassende Hinweise zu den Fließkriterien 25 2.4 Kennwertermittlung und Werkstoffcharakterisierung 26 2.4.1 Experimentelle Methoden und analytische Verfahren zur Fließortkurvenermittlung 26 2.4.2 Erweiterte Messtechnik zur Identifikation von Fließortkurven 33 2.4.3 Inverse Strategien zur Identifikation von Fließortkurven 36 2.5 Zusammenfassung zum Stand der Technik 43 3 Zielsetzung und Vorgehensweise 45 3.1 Zielsetzung 45 3.2 Vorgehensweise 45 4 Experimentelle Versuchsdurchführung 47 4.1 Versuchsaufbau und Messtechnik 47 4.2 Prüfverfahren zur Werkstoffprüfung 48 4.2.1 Zugversuch 49 4.2.2 Kerbzugversuch 49 4.2.3 Scherzugversuch 49 4.2.4 Biaxialer Zugversuch 50 4.3 Wahl der Versuchswerkstoffe 51 4.3.1 Kaltgewalzter Tiefziehstahl DX54 51 4.3.2 Kaltgewalzter Dualphasenstahl DP600 52 4.3.3 Aluminiumknetlegierung AA5182 52 4.4 Messergebnisse aus den Werkstoffprüfungen 53 4.5 Zusammenfassung zur Versuchsdurchführung 55 5 Entwicklung einer halbanalytischen Methode zur Parameteridentifikation 56 5.1 Spannungsanalyse 56 5.1.1 Spannungsrichtung 57 5.1.2 Spannungszuwachs 58 5.1.3 Elastische Kompensation 59 5.2 Schnittkraftermittlung 60 5.3 Inverse Analyse 62 5.4 Zusammenfassende Darstellung der Entwicklung 64 6 Validierung der Methode an virtuellen Experimenten 67 6.1 Virtuelle Versuche 67 6.2 Validierung der Spannungsanalyse 68 6.2.1 Vorgehensweise zur Prüfung der Spannungsanalyse 69 6.2.2 Ergebnisse der Überprüfung der Spannungsanalyse 70 6.3 Validierung der Schnittkraftermittlung 76 6.4 Sensitivität der Materialantwort gegenüber den Materialparametern 80 6.4.1 Einfluss variierender Fließkurvenapproximationen 80 6.4.2 Einfluss variierender Fließortkurven 82 6.5 Diskussion zur Wahl geeigneter Schnittlinien 88 6.6 Fehlerbetrachtung 89 / Numerical process analysis is widely used today for the virtual process validation of the production of formed sheet metal parts. In this context, sufficiently precise material modeling is essential, especially for the flow behavior and the material anisotropy. Numerous test and evaluation strategies are known for the material characterization. However, these strategies are only used occasionally in industrial applications due to high experimental and computational costs. In the context of this work, a newly developed semi-analytical method for the characterization of yield locus curves and subsequent yield locus curves is presented. For this purpose, a stress analysis based on digital image correlation data and a cutting-line approach for internal forces computation was developed. By balancing these internal cutting forces with measured external test forces, parameters of a material model are identified in an inverse analysis. The method for parameter identification was first examined on synthetic and subsequently on real experiments. A sequential identification strategy was set up and examined on the sheet metal materials DX54, DP600 and AA5182. Finally, the method was checked using validation tests with regard to the identified material responses.:Inhaltsverzeichnis I Symbolverzeichnis IV Abkürzungen und Begriffe VIII 1 Einleitung 1 2 Stand der Technik 3 2.1 Grundlagen zur Umformung von Blechwerkstoffen 3 2.1.1 Umformprozesse zur Herstellung von Blechformteilen 3 2.1.2 Anforderungen bei der Herstellung von Blechbauteilen 4 2.2 Numerische Prozessauslegung von Blechumformoperationen 5 2.2.1 Anwendung der FEM als Hilfsmittel in der Prozessauslegung 5 2.2.2 Kritische Punkte der numerischen Prozessauslegung 7 2.3 Werkstoffverhalten und Materialmodellierung 8 2.3.1 Kenngrößen zur Beschreibung großer Deformation 8 2.3.2 Grundlagen zur Beschreibung elastoplastischen Materialverhaltens 9 2.3.3 Beschreibung der Verfestigungsregel in Materialmodellen 11 2.3.4 Modellierung anisotroper Fließortkurven 12 2.3.5 Modellierung der Fließortkurvenentwicklung 18 2.3.6 Zusammenfassende Hinweise zu den Fließkriterien 25 2.4 Kennwertermittlung und Werkstoffcharakterisierung 26 2.4.1 Experimentelle Methoden und analytische Verfahren zur Fließortkurvenermittlung 26 2.4.2 Erweiterte Messtechnik zur Identifikation von Fließortkurven 33 2.4.3 Inverse Strategien zur Identifikation von Fließortkurven 36 2.5 Zusammenfassung zum Stand der Technik 43 3 Zielsetzung und Vorgehensweise 45 3.1 Zielsetzung 45 3.2 Vorgehensweise 45 4 Experimentelle Versuchsdurchführung 47 4.1 Versuchsaufbau und Messtechnik 47 4.2 Prüfverfahren zur Werkstoffprüfung 48 4.2.1 Zugversuch 49 4.2.2 Kerbzugversuch 49 4.2.3 Scherzugversuch 49 4.2.4 Biaxialer Zugversuch 50 4.3 Wahl der Versuchswerkstoffe 51 4.3.1 Kaltgewalzter Tiefziehstahl DX54 51 4.3.2 Kaltgewalzter Dualphasenstahl DP600 52 4.3.3 Aluminiumknetlegierung AA5182 52 4.4 Messergebnisse aus den Werkstoffprüfungen 53 4.5 Zusammenfassung zur Versuchsdurchführung 55 5 Entwicklung einer halbanalytischen Methode zur Parameteridentifikation 56 5.1 Spannungsanalyse 56 5.1.1 Spannungsrichtung 57 5.1.2 Spannungszuwachs 58 5.1.3 Elastische Kompensation 59 5.2 Schnittkraftermittlung 60 5.3 Inverse Analyse 62 5.4 Zusammenfassende Darstellung der Entwicklung 64 6 Validierung der Methode an virtuellen Experimenten 67 6.1 Virtuelle Versuche 67 6.2 Validierung der Spannungsanalyse 68 6.2.1 Vorgehensweise zur Prüfung der Spannungsanalyse 69 6.2.2 Ergebnisse der Überprüfung der Spannungsanalyse 70 6.3 Validierung der Schnittkraftermittlung 76 6.4 Sensitivität der Materialantwort gegenüber den Materialparametern 80 6.4.1 Einfluss variierender Fließkurvenapproximationen 80 6.4.2 Einfluss variierender Fließortkurven 82 6.5 Diskussion zur Wahl geeigneter Schnittlinien 88 6.6 Fehlerbetrachtung 89

This study aims to introduce a new qualification approach designed to enhance the overall integrity of complex cooling structures in gas turbine blades produced through 3D printing, with a focus on achieving maximum density. The primary objective is to present a comprehensive qualification and validation methodology tailored for components manufactured via binder jetting printing and non-selective laser melting (SLM) powder-based atomic diffusion additive manufacturing. This innovative qualification approach undergoes validation through stages encompassing design, printing, comprehension of thermal debinding and sintering processes, post-processing, optimization, and characterization, all aimed at achieving complex cooling structures with optimal density using stainless steel material and In718 as a case study. Subsequently, the material properties obtained are compared with those of IN718 produced via laser-based manufacturing. Thorough characterization is conducted before and after sintering to assess the impact of sintering on density enhancement. Experimental optimization employing the Taguchi matrix with an L9 orthogonal array involves the selection of three key parameters: sintering time, sintering temperature, and heat treatment. The procedural framework established in this research applies to high-temperature applications wherein components are fabricated using atomic diffusion additive manufacturing or binder jetting printing techniques. Testing and inspection procedures involve neutron scattering, radiography, and CT scanning methods, with a specific emphasis on neutron scattering measurements conducted under externally heated and internally cooled conditions to evaluate residual strains within the gas turbine environment. Understanding the interplay between residual stresses originating from manufacturing processes and thermal stresses provides valuable insights into the impact of additive manufacturing on component performance in thermal environments, thus contributing to the advancement of the proposed study.

Es wurde die Optimierungssoftware SPC-Opt entwickelt, mit welcher sich Aufgaben aus den Bereichen der Formoptimierung sowie der Material- und Formidentifikation bearbeiten lassen. Zur Lösung von Identifikationsproblemen steht eine robuste Implementierung des Levenberg-Marquardt-Fletcher-Verfahrens zur Verfügung. Ergänzt wird dieses durch Line-Search- und Trust-Region-Verfahren, welche sich besonders für Aufgaben der Formoptimierung eignen. Es wurden effiziente Algorithmen zur Approximation der Hesse-Matrix sowie verschiedene Verfahren zur Startparametervariation integriert. Das Programm verfügt über Schnittstellen zur Nutzung von ABAQUS, ANSYS, MSC.MARC, eigenen FEM-Programmen sowie LUA-Skripten. Für Formoptimierungen können geometrische Konturen durch NURBS approximiert und deren Kontrollpunkte als Formparameter genutzt werden. Die Aktualisierung der FEM-Netze entsprechend der Formparameteränderung erfolgt durch ein analytisches Verfahren. Der zweite Schwerpunkt der Arbeit bezieht sich auf die Weiterentwicklung bestehender Verfahren zur Materialparameteridentifikation im Bereich der Gummiwerkstoffe. Hierbei wurde das Konzept der Anpassung anhand bauteilnaher Probekörper entwickelt. Dabei wurde am Beispiel einer Fahrwerksbuchse ein Probekörper entworfen, welcher dem originalen Bauteil zwar ähnlich sieht, jedoch eine deutlich einfachere Geometrie hat. Durch diesen konnte das Verhalten des Bauteils gut approximiert und sichergestellt werden, dass die im Rahmen der Parameteridentifikation durchgeführten FEM-Simulationen sicher konvergieren. Zudem wurden die Nutzerschnittstellen des inelastischen Morph-Stoffgesetz für MSC.MARC und ABAQUS weiterentwickelt, sodass diese nunmehr auch im industriellen Umfeld nutzbar sind. Es konnte nachgewiesen werden, dass die Verwendung bauteilnah identifizierter Parameter zu einer erheblich besseren Abbildung des Materialverhaltens führt als die Verwendung anhand von Standardprobekörpern identifizierter Parameter. Weiterhin zeigte sich, dass vor allem der Einsatz eines Stoffgesetzes mit der Möglichkeit zur Abbildung des charakteristischen Verhaltens von Elastomeren unbedingt erforderlich ist. / Within the scope of this work the optimization software SPC-Opt has been developed to successfully process tasks in the fields of shape optimization and parameter identification. The software includes a robust Levenberg-Marquardt-Fletcher algorithm, several line search and trust region algorithms as well as efficient methods for the approximation of the Hessian matrix. Additionally, procedures for the variation of initial parameters (Design Of Experiments) were implemented. The software includes interfaces to ABAQUS, ANSYS, MSC.MARC, in-house FEM programs and LUA scripts. Within shape optimization problems, geometric shapes are approximated by NURBS and the related control points are employed as design variables. For the update of the FE mesh during the variation of the design variables, a special analytical algorithm is used to preserve the mesh topology. Another focus is related to the further development of existing material parameter identification procedures for rubber materials. Therefor, the concept of component-oriented specimens was developed. Using the example of a bushing, a specimen was designed, which is similar to the original component but has a much simpler geometry. According to this, the behavior of the original component is approximated and the stability of necessary FE simulations is ensured. Additionally, the utilized Model of Rubber Phenomenology (MORPH) is improved in view of the industrial use. It is shown that the identification of material parameters using component-oriented specimens leads to a much better approximation of the original component behaviour than using standard specimens. Additionally, it is shown that the use of a material law which can consider characteritic properties of elastomers, is absolutely necessary.

Les ondes acoustiques et électromagnétiques offrent des méthodes de caractérisation des matériaux très peu invasives. Souvent utilisées à l'aide de capteurs indépendants, l'approche développée ici est de proposer un résonateur multimodal acoustique et électromagnétique. Afin de répondre à une grande variété d'applications, le choix de l'élément actif piézo-électrique s'est porté sur un disque de quartz de coupe AT. L'étude s'articule autour des étapes aboutissant in fine à un capteur magnéto acoustique on-chip à excitation sans contact.L'étude théorique d'un capteur magnéto-acoustique à excitation inductive est tout d'abord réalisée pour un capteur chargé par un fluide visqueux. Ce capteur est constitué de trois éléments : une sonde radiofréquence (RF), un résonateur RF à fort facteur de qualité et le quartz sur lequel ont été déposées deux électrodes en anneau. Cette étude montre comment déduire la viscosité complexe du matériau étudié à partir de l'impédance électrique du système complet. Les mesures effectuées sur des mélanges étalons montrent une très bonne correspondance avec les résultats théoriques.L'intégration du résonateur RF sur l'élément piézo-électrique s'effectuant via des électrodes circulaires, une étude préliminaire est menée sur les ondes acoustiques pouvant être générées sur le quartz et leur interaction avec les électrodes. Les mesures de vibration par vibrométrie laser montrent que des ondes de Lamb sont générées dans une large gamme de fréquence (de 100 kHz à 20 MHz). L'analyse de la réponse impulsionnelle spatiale par transformée de Gabor 3D localise la source de ces ondes sur le bord des électrodes. Par ailleurs, l'étude du disque au fondamental montre une grande non-linéarité mécanique du quartz.Le modèle de résonateur RF plan multi-tour puis son intégration sur le disque de quartz du capteur magnéto-acoustique on-chip sont ensuite étudiés. Les résultats expérimentaux par mesure d'impédance et vibrométrie laser valident le modèle. La gamme de fréquence sélectionnée (entre 5 et 20 MHz) permet d'envisager des mesures micro-rhéologiques. / Acoustic and electromagnetic waves are key probing candidates for characterizing their propagation media with minimum perturbation. Often used with independent sensors based on specialized transducing materials, the approach developed here provides an on-ship multimodal sensor using the same sensing material for probing the acoustic and electromagnetic properties of the material. To meet a wide range of applications, the choice of the active piezoelectric element is carried out on an AT cut quartz. The study focuses on the steps leading in fine to an on-chip magneto-acoustic sensor with a contactless excitation.The theoretical study of a magneto-acoustic sensor inductively excited and loaded by a viscous fluid is first carried out. This sensor consists of three elements: a radio frequency (RF) sensor, a high quality factor RF resonator and a quartz on which two ring electrodes have been deposited. The complex viscosity of the studied material is derived from the electrical impedance of the complete system. The measurements carried on etalon viscoelastic materials show a good agreement with the theoretical results.The integration of the RF resonator on the piezoelectric element being via circular electrodes, a preliminary study is performed for determining the acoustic waves that can be generated in the quartz and their interaction with the electrodes. The laser vibrometry measurements indicate that Lamb waves are generated in a wide frequency range, from 100 kHz to 20 MHz. The analysis of the spatial pulse response of the sensor surface by 3D Gabor transform locates the source of these waves on the edge of the electrodes. Furthermore, the study of the disk at it fundamental frequency points out the high nonlinear mechanical behavior of the quartz.The plane RF multi-turn resonator and its integration on the quartz disk of the magneto-acoustic on-chip sensor are then studied. The experimental results of impedance and laser vibrometry measurements validate the proposed theoretical model. The selected frequency range (between 5 and 20 MHz) allows one to consider micro rheological measurements.

Ce travail se situe à l’intersection des trois disciplines : méthodes numériques, techniques expérimentales et du machine learning, a pour but de proposer une famille de techniques d’identification par analyse inverse des lois de comportement en mécanique. Dans le domaine d’identification des matériaux, l’indentation instrumentée est particulièrement attractive, car elle permet de procéder à des essais non-destructifs sur l’échantillon ou sur une structure en service. L’essai d’indentation, similaire à un test de dureté, consiste à enfoncer la pointe de l’indenteur à une faible profondeur dans la matière tout en enregistrant le déplacement en fonction de la force appliquée. L’identification des propriétés élastoplastiques des matériaux est basée alors sur l’exploitation de la courbe force-déplacement (courbe P-h). Toutefois, le problème inverse est souvent mal posé et des problèmes d’unicité mènent à la notion de paires de "matériaux mystiques" produisant, dans des conditions d’essai donnés, des courbes P-h identiques, malgré des propriétés différentes. L’idée de notre travail est de compléter la procédure d’identification en faisant appel à des dispositifs expérimentaux récents, notamment à la microscopie laser, permettant de mesurer la carte 3D de l’empreinte résiduelle obtenue après le retrait de l’indenteur. Pour aborder la question de la richesse d’information de l’empreinte par rapport à la courbe P-h seule, nous proposons de construire, dans un espace affine réduit, la variété des formes d’empreinte admissibles au sens d’une loi de comportement et du modèle d’éléments finis de l’essai. La mesure de la dimension intrinsèque nous indique alors le nombre maximal de paramètres potentiellement identifiables. Cela nous permet de proposer et de valider numériquement des nouveaux procédés expérimentaux, plus représentatifs, à partir des données synthétiques, ainsi que des algorithmes d’identification associés. La prise en compte de l’erreur de modèle et de l’erreur de mesure, nous mène ensuite à proposer un ensemble d’algorithmes de projection d’empreintes expérimentales, réalisées en collaboration avec l’INSA de Rennes sur la variété synthétique. Nous abordons alors le problème d’identification des propriétés d’écrouissage de plusieurs matériaux de complexité croissante et départageons des "jumeaux mystiques" par des essais de multi-indentation, basés sur l’exploitation de l’empreinte seule ou en complément de la courbe P-h. / The thesis lies at the intersection of three disciplines : numerical methods, experimental techniques, and machine learning. The primary aim of this work is to develop a group of algorithms for characterization by inverse analysis of a material’s constitutive law. In the field of material characterization, indentation test is especially attractive since it is considered non-destructive, and may be performed even on a structure in service. The test, similar to a hardness test, consists in penetrating an indenter into the surface of the material. The force exerted on the indenter is recorded against the penetration depth over a series of time instants, leading to a force-displacement (P-h) curve, which is the most frequently used source of information for the identification of material properties. However, the inverse problem based solely on this curve tends to be ill-posed, leading to nonunique identification solution, i.e., the "mystical material pair", for whom the corresponding force-displacement curves are almost identical despite the very different material properties. The basic idea is then to complete the identification process with innovative experimental measurements, such as laser microscope, which allows measuring the 3D residual imprint after the withdrawal of the indenter. To address the advantage of this measurement over P-h curve, we propose to construct, within a reduced affine space, a manifold of shapes admissible to the postulated constitutive law, experimental and simulation setups, based on synthetic data. The intrinsic dimensionality of the manifold limits the number of identifiable parameters allowing to validate numerically experimental procedures. Considering both the model and measurement errors, we develop a series of local manifold learning algorithms to solve the inverse problem iteratively for experimental results obtained in cooperation with INSA de Rennes. This approach allows us to characterize diverse metallic materials of increasing complexity, based on actual experimental measurements. For example, for the Hollomon’s law, the mystical pair is alleviated in using a single imprint, while for the Voce law, a multi-depth experimental protocol is proposed to differentiate mystical siblings.

Wireless communications have been an indispensable aspect of everyday life, and there is an increasing consumer demand for accessing several wireless communication technologies from a single, compact, mobile device. System-on-package (SOP) technology is an advanced packaging technology that has been proven to realize the convergence of multiple functions into miniaturized, high-performance systems to meet this demand. With the advancements in the SOP technology, the miniaturization of the front-end module has been achieved using embedded passives in multilayer packages. However, the integration of the antenna directly on the module package is still the barrier to achieve a fully-integrated, high-performance RF SOP system. The main reason for this missing link is that integrating the antenna on the package requires miniaturizing the antenna, which is a difficult task. The focus of this dissertation is to design high-performance antennas along with developing techniques for miniaturization and system-on-package (SOP) integration of these antennas to achieve fully-integrated SOP systems using advanced multilayer organic substrates and thin-film magneto-dielectric materials. The targeted spectrum for the antenna designs are 2.4/5 GHz WLAN/WiMAX and 60 GHz WPAN bands. Several novel antenna designs and configurations to integrate the antenna on the package along with the module are discussed in this dissertation. The advanced polymers used in this research are Liquid Crystalline Polymer (LCP), RXP, and thin-film magneto-dielectrics.

The current clinical management of abdominal aortic aneurysm (AAA) disease is based on measuring the aneurysm maximum diameter to decide when timely intervention can be recommended to a patient. However, other parameters may also play a role in causing or predisposing the AAA to either an early or delayed rupture relative to its size. Therefore, patient-specific assessment of rupture risk based on physical principles such as individualized biomechanics can be conducive to the development of a vascular tool with translational potential. To that end, the present doctoral research materialized into a framework for image based patient-specific vascular biomechanics assessment. A robust generalized approach is described herein for image-based volume mesh generation of complex multidomain bifurcated vascular trees with the capability of incorporating regionally varying wall thickness. The developed framework is assessed for geometrical accuracy, mesh quality, and optimal computational performance. The relative influence of the shape and the constitutive wall material property on the AAA wall mechanics was explored. This study resulted in statistically insignificant differences in peak wall stress among 28 AAA geometries of similar maximum diameter (in the 50 – 55 mm range) when modeled with five different hyperelastic isotropic constitutive equations. Relative influence of regionally varying vs. uniform wall thickness distribution on the AAA wall mechanics was also assessed to find statistically significant differences in spatial maxima of wall stresses, strains, and strain energy densities among the same 28 AAA geometries modeled with patient-specific non-uniform wall thickness and two uniform wall thickness assumptions. Finally, the feasibility of estimating in vivo wall strains from individual clinical images was evaluated. Such study resulted in a framework for in vivo 3D strain distributions based on ECG gated, unenhanced, dynamic magnetic resonance images acquired for 20 phases in the cardiac cycle. Future efforts should be focused on further development of the framework for in vivo estimation of regionally varying hyperelastic, anisotropic constitutive material models with active mechanics components and the integration of such framework with an open source finite element solver with the goal of increasing the translational potential of these tools for individualized prediction of AAA rupture risk in the clinic.

A ce jour il n'est toujours pas possible de prédire avec exactitude le phénomène d'érosion par cavitation. La raison principale est qu'il est difficile de caractériser l'agressivité de l'écoulement. Cette thèse propose d'utiliser une méthode inverse pour estimer l'agressivité de l'écoulement à partir de l'observation des cratères (pits) imprimées sur la surface dans les premiers instants de l'érosion de cavitation. Trois matériaux ont été testés dans la veine d'écoulement PREVERO disponible au LEGI de Grenoble dans les mêmes conditions expérimentales. La géométrie des pits laissés sur la surface est précisément mesurée à l'aide d'une méthode systématique permettant de s'affranchir de l'effet de rugosité. Supposant que chaque pit a été généré par une bulle unique dont le champ de pression est assimilé à une forme Gaussienne, des calculs par éléments finis permettent d'estimer le chargement qui a créé l'empreinte résiduelle. On montre que la distribution des chargements suit une loi universelle indépendante du matériau testé; le matériau le plus tendre (alliage d'aluminium) mesurant les plus faibles impacts tandis que le matériau le plus résistant (Acier inoxydable) donne accès aux plus grandes pressions d'impact. On en conclu que le matériau peut être utilisé comme capteur de pression mesurant le niveau d'agressivité de l'écoulement. La méthode inverse repose sur une caractérisation mécanique des matériaux prenant en compte la sensibilité de la contrainte à la vitesse de déformation. On montre que les essais de nanoindentation sont mieux adaptés que les essais de compression pour déterminer les paramètres de la loi de comportement, notamment pour l'alliage d'aluminium pour lequel la microstructure est très hétérogène. Des essais de compression à haute vitesse par barres de Hopkinson complètent la loi de comportement en donnant la sensibilité à la vitesse de déformation. Des simulations prenant en compte la dynamique du chargement montrent que des impacts de fort amplitude mais appliqués sur un temps court ne laissent pas d'empreinte résiduelle si la fréquence est plus élevée que la fréquence naturelle du matériau assimilé à un oscillateur amorti. Un mécanisme d'accumulation dynamique de la déformation plastique pouvant conduire à la rupture par fatigue est proposé. Finalement, la courbe de perte de masse est simulée en appliquant aléatoirement sur un maillage 3D, la population d'impacts estimée par la méthode inverse. / Numerical prediction of cavitation erosion requires the knowledge of flow aggressiveness, both of which have been challenging issues till-date. This thesis proposes to use an inverse method to estimate the aggressiveness of the flow from the observation of the pits printed on the surface in the first moments of the cavitation erosion. Three materials were tested in the same experimental conditions in the cavitation tunnel PREVERO available LEGI Grenoble. The geometry of the pits left on the surface is precisely measured using a systematic method to overcome the roughness effect. Assuming that each pit was generated by a single bubble collapse whose pressure field is treated as a Gaussian shape, finite element calculations are run for estimating the load that created each residual imprint. It is shown that the load distribution falls on a master curve independent of the tested material; the softer material (aluminum alloy) measuring the lowest impacts while the most resistant material (duplex stainless steel) provides access to the largest impact pressures. It is concluded that the material can be used as a pressure sensor measuring the level of aggressiveness of the flow. The inverse method is based on a material characterization taking into account strain rate effects. It is shown that nanoindentation tests are more suitable than compression tests to determine the parameters of the behavior law, particularly for the aluminum alloy for which the microstructure is very heterogeneous. High-speed compression tests with split Hopkinson pressure bars complement the constitutive law giving the sensitivity to the strain rate. Simulations considering the dynamic loading show that impacts of strong amplitude but applied in a short time do not leave any residual pit if the frequency is higher than the natural frequency of the material treated as a damped oscillator. A dynamic mechanism of plastic strain accumulation that could eventually lead to fatigue failure is proposed. Finally, the mass loss curve of cavitation erosion is simulated by applying randomly on a 3D mesh, the impact force population estimated by the inverse method.

Key factors that influence the design of paved and unpaved roads are the strength and stiffness of the pavement layers. Among other factors, the strength of pavements depends on the thickness and quality of the aggregates used in the pavement base layer. In India and many other countries, there is a high demand for good quality aggregates and the availability of aggregate resources is limited. There is a need for the development of sustainable construction methods which can handle aggregate requirements with least available resources and provide good performance. Hence it is imperative to strive for alternatives to achieve improved quality of pavements using supplementary potential materials and methods. The strength of pavement increases with increase in the thickness of the base which has a direct implication on construction cost whereas decreasing the thickness of the base makes it weak which results in low load bearing capacity especially for unpaved roads. The use of different types of geosynthetics like geocell and geogrid are a potential and reliable solution for the lack of availability of aggregates and studies are conducted in this direction. To better understand the performance of any geosynthetically reinforced base layers, it is essential to characterize the pavement material by studying the behavior of these materials under static as well as repeated loading. For unpaved roads, the base layer, made of granular aggregates plays a crucial role in the reduction of permanent deformation of the pavements. The resilient modulus (Mr) of these materials is a key parameter for predicting the structural response of pavements and for characterizing materials in pavement design and evaluation. Usually, during the design of flexible pavements, pavement materials are treated as homogeneous and isotropic. The use of rollers in the field during pavement construction leads to a higher compaction of material in the vertical direction which introduces stress-induced anisotropy in the base material. The effect of stress-induced anisotropy on the properties of the granular material is studied and discussed in the first part of the research by conducting repeated load triaxial tests. Isotropic consolidated and anisotropically consolidated samples were prepared to investigate the behavior of base materials under stress induced anisotropic conditions. An additional axial load was applied on the isotropically consolidated sample to create anisotropically consolidated sample. The axial loading was provided such that the stress ratio (σ1/σ3), during anisotropic consolidation was kept constant for all the tests at different confining pressures. The effect of repeated loading on the permanent deformation and the resilient modulus for both isotropically and anisotropically consolidated samples, at different confining pressure and loading conditions, are discussed. The behavior of both anisotropically and isotropically consolidated samples has been explained using the record of the excess pore pressures generated during the experiments. The experimental studies show that the permanent strains measured in the vertical direction of the anisotropically consolidated samples are less compared to the results obtained for isotropically consolidated samples. The resilient moduli of the anisotropically consolidated samples were also observed to be higher than that of the isotropically consolidated sample. The study conducted on the pore pressure of both the samples explains better performance of the anisotropically consolidated samples. The studies showed that the isotropically consolidated samples showed higher pore pressures compared to the anisotropically consolidated specimens. Another factor which influences the resilient modulus of the pavement materials is the geosynthetic reinforcement. Geocell and geogrid reinforced triaxial samples were prepared to study the effect of reinforcement in the resilient modulus of the base materials. From the literature, it can be seen that most of the research in the triaxial testing equipment were carried out in the non-destructive range of confining pressure and deviatoric stress. Several studies have been conducted by the researchers to visualize the pavement response in the elastic range. However, the studies in the plastic creep range and incremental collapse range were highly limited. In the current study, testing is carried out on the triaxial samples for two different stress ranges. In the first sections, loading was applied in the elastic and elastic shakedown range as per AASTHO T-307. For various loading sequences, a comparative analysis has been done for the resilient modulus of the geogrid and geocell. In the next section, the loading was applied on the sample in the plastic shakedown range and incremental collapse range. The results of the permanent strains and resilient modulus of the sections are compared with the corresponding results of the unreinforced section. In the plastic shakedown and incremental collapse range also the permanent strains of reinforced samples were less than those observed in the unreinforced section. The performance of geosynthetically reinforced pavement layers can be better understood by studying the samples prepared under realistic field conditions. In the case of triaxial experiments the sample size is very less compared to the field conditions and the effect of other pavement layers on the performance of the base layers cannot be studied on triaxial samples. Samples were prepared in the laboratory by modeling the pavement sections in a cuboidal tank, in which different pavement layers are laid one over the other, and a static loading or repeated loading is applied to overcome the bottleneck of small sample size in the triaxial setup. The experiments were conducted on the unreinforced section; geocell reinforced section and geogrid reinforced section placed above strong and weak subgrade. The results of the study are examined regarding the resilient deformation, permanent deformation, pressure distribution and strain measurements for different thicknesses of base layers under repeated loading. The initial parts of the study present the results of experiments and analysis of the results to understand the behavior of geocell reinforced granular base during repeated loading. In this study, an attempt is made to understand the various factors which influence the behavior of geocell reinforced granular base under repeated loading by conducting plate load tests. The loads applied on the pavements are much higher than the standard axle loading used for the design of pavements. High pressure was applied on all the test sections to simulate these higher loading conditions in the field. The optimum width and height of the geocell to be provided, to get maximum reduction in permanent deformation is studied in detail. The effect of resilient deformation of reinforced and unreinforced base layers is quantified by calculating the resilient modulus of these layers. The studies showed that the geocell reinforcement was effective in reducing the permanent and resilient deformations of base layer when compared to the unreinforced samples. The resilient modulus calculated was higher for the reinforced sample with half of the thickness of the unreinforced sample. The effect of reinforcement in the stress distribution within the base layer is also studied by measuring the pressures at different depths of the base layer. The results showed that the pressure getting transferred to the subgrade level was much lower in the case of geocell reinforced base layer. The ultimate aim of any pavement design method is to reduce the distress in the subgrade level and thus leading to increased life of pavements. Pressures at the subgrade level for reinforced and unreinforced sections are studied in detail, the main parameter under study being the stress distribution angle, to investigate the distress in the subgrade level. It was observed that the geocell reinforced sample showed higher stress distribution angle when compared to its unreinforced counterpart. Another important factor that has to be studied is the strains at the subgrade level since it is the governing factor of causing rutting in the pavements. From the experiments conducted in the study, it was shown that the reinforcement is very effective in reducing the strains at the top of subgrades. The implications of the current study are brought out in terms of improved pavement performance as the carbon emission reductions. It is important to analyze the performance of reinforced section under realistic field conditions. To do that experiment were conducted on reinforced and unreinforced base layers placed on top of weak subgrade material. The study showed that the reinforcements are effective in reducing the deformations under weak subgrade conditions also but not as effective as it was under strong subgrade case. The experimental results were then validated with the two-dimensional mechanistic-empirical model for geocell reinforced unpaved roads for predicting the performance of pavements under a significant number of cycles. The modified permanent deformation model which incorporates the triaxial test results and strains measured directly from the base sections were used to model and validate. Plate load experiments were also conducted on base layers reinforced with geogrid to understand the behavior of these reinforced samples under repeated loading. Several factors like the width of the geogrid to be provided and the depth of placing the geogrid in the base layer were studied in detail to achieve maximum reduction in deformations. Permanent and resilient deformation studies were carried out for both reinforced and unreinforced sections of varying thicknesses, and a comparison was made to understand the effect of reinforcement. The geogrid reinforcement could effectively reduce the permanent and resilient deformations when compared to the unreinforced sections. A study was also carried out on the resilient modulus, which explained the better performance of the geogrid reinforced samples by showing higher resilient modulus for reinforced samples than the unreinforced specimens. The performance of the geogrid reinforced base layers was further verified by studying the pressure distribution at the subgrade level and by calculating the stress distribution angle corresponding to the reinforced and unreinforced samples. The strains at the subgrade level were also studied and compared with the unreinforced sample which showed a better performance of geogrid reinforced samples. The results from the strain gauges fixed in the geogrid were further used to model and validate the permanent deformation model. Experiments were conducted on geogrid-reinforced base layer placed above weak subgrade conditions. The results showed that the reinforcement was effective in reducing the deformations under weak subgrade conditions also. Apart from conducting the laboratory studies, experimental results were numerically modeled to accurately back-calculate the resilient moduli of the layers used in the study. 3D numerical modeling of the unreinforced and honeycomb shaped geocell reinforced layers were carried out using finite element package of ANSYS. The subgrade layer, geocell material, and infill material were modeled with different material models to match the real case scenario. The modeling was done for both static and repeated load conditions. The material properties were changed in a systematic fashion until the vertical deformations of the loading plate matched with the corresponding values measured during the experiment. The experimental study indicates that the geocell reinforcement distributes the load in the lateral direction to a relatively shallow depth when compared to the unreinforced section. Numerical modeling further strengthened the results of the experimental studies since the modeling results were in sync with the experimental data.