Les matériaux composites ont connu ces dernières années une forte croissance, croissance aujourd'hui renforcée par les nouvelles normes européenne visant à diminuer les émissions CO2 d'ici 2020. La réalisation de pièces complexes peut poser de nombreuses problématiques de fabrication comme la formation de zones sèches, ou la création de distorsions géométriques. Les origines de ces problématiques sont souvent liées à un manque de connaissance et de maîtrise des phases d'imprégnation des renforts et de cuisson du matériau. L'amélioration de la robustesse des procédés nécessite d'avoir une connaissance fine des phénomènes physiques qui ont lieu lors de l'élaboration. Dans cette perspective, les procédés d'élaboration de matériaux composites ont été étudiés à travers la mise en place d'un démonstrateur de laboratoire dans le cadre du projet LCM Smart. Ce pilote d'injection a permis de valider des solutions d'instrumentation, à partir de capteurs innovants (OFS) développés en partenariat avec le laboratoire d'optique Hubert Curien.L'application de cette instrumentation dans le cadre du suivi du procédé RTM a démontré les capacités des OFS pour le suivi des caractéristiques physiques de la pièce (le front d'écoulement, la température, les déformations résiduelles et le degré de cuisson). La comparaison des caractéristiques mesurées avec des simulations numériques effectuées en collaboration avec ESI, a montré une bonne corrélation.Enfin, l'instrumentation a permis de mettre en évidence l’intérêt d’un outillage composite en HexTool pour la réduction des contraintes résiduelles liées à l'interaction outil/pièce. / A significant growth in production and consumption of composite materials can be seen recently; growth reinforced by the new European standards, aimed at reducing CO2 emissions by the year 2020.The producing of complex parts can cause many difficulties for manufacturing because of their geometries and / or their constituents (using of various materials). For example, dry zones or geometric distortion formation. The origins of these difficulties are often related to a lack of knowledge and control of the reinforcement's impregnation phases and material curing.Improving the robustness of the processes demands a detailed knowledge of physical phenomena that occur during the producing. For this, we studied the composite materials production through the implementation of a laboratory demonstrator in the project LCM Smart. This pilot injection was used to validate instrumentation solutions, from innovative sensors (OFS) developed in partnership with the optical laboratory Hubert Curien. The application of this instrumentation in the context of RTM process monitoring in the development of simple parts has demonstrated the capabilities of OFS to control physical characteristics of the part (the flow front, temperature, residual strain and curing degree). The comparison of the measured characteristics with numerical simulations carried out in collaboration with ESI showed a good correlation.Finally, instrumentation has demonstrated the capacity of composite tool made by HexTool to minimize the residual stresses due to the tool/part interaction.

Submitted by Nayara Passos (nayara.passos@ufpe.br) on 2015-03-11T17:12:54Z No. of bitstreams: 2 TESE Abner Correa Barros.pdf: 14913537 bytes, checksum: 00c434893f2196bab70791b8218a2bbe (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Approved for entry into archive by Daniella Sodre (daniella.sodre@ufpe.br) on 2015-03-13T13:03:45Z (GMT) No. of bitstreams: 2 TESE Abner Correa Barros.pdf: 14913537 bytes, checksum: 00c434893f2196bab70791b8218a2bbe (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-13T13:03:45Z (GMT). No. of bitstreams: 2 TESE Abner Correa Barros.pdf: 14913537 bytes, checksum: 00c434893f2196bab70791b8218a2bbe (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2014 / Cenpes, Petrobras, Finep. / Nestes últimos anos, com o início da prospecção de petróleo em regioões com litologias complexas, tem se observado um crescente interesse no uso do algoritmo Reverse Time Migration(RTM) como solução para o imageamento sísmico. Devido ao seu elevado custo computacional, o algoritmo RTM exige o uso de sistemas computacionais de alto desempenho, os quais demandam investimentos elevados em infraestrutura, o que normalmente representa também um aumento substancial no consumo de energia. Neste cenário, o desenvolvimento de coprocessadores aritméticos de alto desempenho, implementados por meio dos Field Programmable Gate Arrays(FPGAs), passou a ser considerado uma alternativa viável no objetivo de aumentar o a capacidade de processamento de sistemas computacionais já existentes, com impactos positivos tanto nos investimentos em infra-estrutura quanto no consumo de energia. Entretanto, o desenvolvimento destes coprocessadores normalmente exige um estudo prévio minucioso das características do algoritmo a ser implementado e do conjunto de dados a ser processado, a fim de determinar a precisão numérica mnima que deve ser empregada em sua implementação. O objetivo deste trabalho foi desenvolver uma metodologia que permita identificar a precisão numérica mínima necessária à implementação do algoritmo RTM, baseado nos fenômenos físicos envolvidos na propagação da onda sísmica e nas litologias prováveis da região a ser imageada. Para chegar a este objetivo foi desenvolvido um método analítico, capaz de predizer a atenuação esperada para as ondas sísmicas durante os processos de modelagem e migração presentes no algoritmo RTM. Esse método foi baseado em uma nova abordagem no tratamento da atenuação por espalhamento geométrico para modelos com múltiplas camadas, denominada de Raio Efetivo. Como estudo de caso de validação dessa metodologia, foram feitas predições e analisados os resultados de imageamento de diversos modelos sintéticos propostos por um especialista em geologia, os quais eram formados apenas por camadas horizontais, planas e paralelas. Além desses modelos mais simples, foi também utilizado um modelo reconhecidamente complexo, conhecido como modelo de marmousi. Os resultados obtidos em todos os estudos se mostraram dentro de uma margem de segurança de 1 bit de precisão.

Hybrid composites play a key role in sustainable development. For many years, carbon fibres in an epoxy matrix have been an attractive option for many structural applications because of their higher specific mechanical properties mostly. However, recycling and sustainability are some of the composite shortcomings; and in that context, natural fibres have gained popularity.  The present study aimed to design and manufacture short carbon/flax hybrid composites. Two different arrangements were chosen: random and layers configuration. Resin Transfer Moulding (RTM) was used to fabricate these hybrid composites. Mechanical tests and optical microscopy technique were conducted to understand the effect of the interaction of these two different reinforcements. Mechanical tests showed a remarkable difference between the hybrid configurations under flexural loadings. Furthermore, outstanding property values were observed in the hybrid configurations compared to single fibre composites. The resultant materials have seemed an attractive combination of fibres with a remarkable balance between mechanical performance and eco-friendliness.

Die Herstellung von ultradünnen Germaniumdioxidfilmen auf Metallsubstraten ist erstmals erfolgreich gelungen. Die Filmstruktur konnte mittels oberflächensensitiven Techniken mit atomarer Präzision und chemischer Sensitivität aufgelöst werden. Zur Untersuchung werden STM-Bilder analysiert und durch niederenergetische Elektronenbeugung (LEED), eine dynamischen LEED-Studie und extern ausgeführte Dichtefunktionaltheorieberechnungen (DFT) ergänzt. In dieser Arbeit werden atomar aufgelöste Rastertunnelmikroskopiebilder (STM) von ultradünnen Germaniumdioxid- und Siliziumdioxidfilmen direkt verglichen. Ziel der Analyse ist es, den Einfluss des Metallsubstrats auf die Struktur von Oxidfilmen zu untersuchen. Zu diesem Zweck werden ultradünne Germaniumdioxid-Filme auf Ru(0001), Pt(111) und Au(111) abgeschieden und mit Siliziumdioxid-Filmen auf verschiedenen Substraten verglichen, die in früheren Studien untersucht wurden. Germaniumdioxid und Siliziumdioxid sind eng miteinader verknüpft. Hierbei sind Struktur und chemische Eigenschaften als äquivalent anzusehen. Es wurden drei verschiedene Netzwerkstrukturen aufgeklärt: Monolagen-, Zickzack- und Bilagenfilme. Die einzelnen Bausteine in diesen Filmsystemen bestehen aus verzerrten Tetraedern, in denen ein Germaniumatom von vier Sauerstoffatomen umgeben ist. Benachbarte Tetraeder sind durch Ge-O-Ge-Bindungen miteinander verknüpft und binden im Fall der Monolagenfilme an das darunterliegende Metallsubstrat. In Bilagenfilmen hingegen gibt es keine chemischen Bindungen zum Substrat, wodurch die Filmstruktur flexibler wird. Durch Variation der Herstellungsbedingungen kann man rein kristalline, amorphe oder Phasen mittlerer Ordnung erhalten. Es ist wichtig hervorzuheben, dass der amorphe Germaniumdioxid-Bilagenfilm ein neues amorphes zweidimensionales Material darstellt. / The preparation of metal-supported ultrathin films of germanium dioxide, termed also germania, has been successfully achieved for the first time. The structure of the films is elucidated with atomic precision and chemical sensitivity using surface science techniques. The investigation is performed by analyzing STM images and is complemented by low-energy electron diffraction (LEED) patterns, a dynamical LEED study, and external support from density functional theory (DFT) calculations. In this work, we compare side-by-side atomically-resolved scanning tunneling microscopy (STM) images of ultrathin films of germania and silica. The analysis aims to investigate the impact of the metal support on the structure of oxide films. For that purpose, ultrathin germania films are grown on Ru(0001), Pt(111) and Au(111), and compared with previously reported silica ultrathin films supported on different substrates. Germania has been widely associated with silica since they are considered to be structural and chemical equivalent materials. Three main network structures have been characterized: monolayer, zigzag and bilayer films. In all systems, the building block consists of a distorted tetrahedron with a germanium atom surrounded by four oxygen atoms. Adjacent tetrahedra connect to each other through Ge-O-Ge bonds and, in the case of the monolayer films, they also bind to the metal support. Conversely, in bilayer films there are no chemical bonds to the metal substrate, thus providing more flexibility to the film structure. Through a meticulous control of the preparation conditions one can obtain a purely crystalline phase, an amorphous one, or one with intermediate order. It is important to highlight that the amorphous germania bilayer film represents a new 2-dimensional amorphous material.

Um hochsensitive räumliche Auflösung zu erreichen, wurden oberflächenverstärkte Raman-Spektroskopie (SERS) und spitzenverstärkte Raman-Spektroskopie (TERS) weiterentwickelt. Das grundlegende Funktionsprinzip ist jedoch noch nicht vollständig verstanden und auch Experimente dazu fehlen teilweise. In dieser Arbeit habe ich zuerst Gap-mode TERS eingesetzt, bei welcher ein starkes elektromagnetisches Feld es ermöglicht, dünne Schichten von sehr schwach streuenden Molekülen zu untersuchen. Mit der Nanometerauflösung von TERS konnte ein auf der Goldoberfläche spontan phasen-getrennten, gemischtes Thiolsystem räumlich aufgelöst werden, während STM die Nanodomänen nicht über ihre Höhenunterschiede erkennen konnte. Neue Studien deuten auf eine Raman-Verstärkung durch Graphen und Flachgold aufgrund eines chemischen Mechanismus hin. Kupfer Phthalocyanin (CuPc)-Moleküle zwischen Graphen und einer flachen Goldoberfläche erlauben Elektronenübertragungen in beide Richtungen und damit stellt sich die Frage, ob chemische Verstärkungen von SERS zueinander addiert werden können. Die Ergebnisse deuten auf eine Kopplung von den zwei einzelnen Oberflächen hin. Es wurde eine 68-fache Verstärkung von geschichtetem CuPc zwischen Graphen und Gold beobachtet, jeweils bezogen auf CuPc auf Glimmer. Zuletzt wurde mittels TERS diese Schichtstruktur untersucht. Moleküle, die sich auf der Goldoberfläche selbstanordnen und mit Graphen bedeckt worden sind, fungieren als optische Sensoren, bei welchen die Graphenverkapselung die Moleküle beschützt. Außerdem kann eine sehr hohe Raman-Verstärkung mit großer lokaler Auflösung aufgrund der kombinierten Effekte von SERS und TERS herbeigeführt werden. Die Ergebnisse zeigen, dass eine Spitze, die Graphen-verstärkte Raman-Streuung (GERS) zusätzlich um vier Größenordnungen verbessern kann, aber Gap-mode TERS abschirmt. / The quest to achieve ultrahigh sensitivity, surface specificity and high spatial resolution has led to the development of plasmon- and chemically- enhanced Raman spectroscopy, including techniques such as surface-enhanced Raman spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS). However, a lack of fundamentally experimental demonstrations still remains. In this thesis, I firstly used gap-mode TERS, which allows studying even molecularly thin layers of very weakly scattering molecules. With the nanoscale spatial resolution provided by TERS, the spontaneous segregation in a mixed thiol system on a gold surface could be resolved, while scanning tunneling microscopy (STM) could not discern the nanodomains via their apparent height difference. Furthermore, since graphene and a flat gold surface both were known to provide some Raman enhancement through mainly a chemical mechanism, sandwiching copper phthalocyanine (CuPc) molecules between graphene and a flat gold surface allowed electrons to be transferred in both directions, and thereby to address the question whether chemical enhancements with different origins in SERS can add to each other. The results suggest that the chemical enhancements were influenced by the two individual surfaces, and a 68-fold enhancement of sandwiched CuPc between graphene and gold was observed, as compared to CuPc on mica. Last, TERS was applied to study this sandwiched structure. Molecules self-assembled on a gold surface and covered by transferred graphene acted as optical probes. Such an arrangement has interesting properties in the sense that molecules are protected and encapsulated by graphene. Also, a possible ultrahigh Raman enhancement together with localized spatial resolution may be achieved due to the combined effects from SERS and TERS. The results showed that a tip can improve graphene-enhanced Raman scattering (GERS) further by 4 orders of magnitude, but graphene exerts some shielding effect to gap-mode TERS.

In this thesis, I explore model systems for planar atomic and molecular scale electronics on surfaces. The nanoscale systems are experimentally investigated by combining scanning tunneling microscopy (STM) with atomic and molecular manipulation. Furthermore, the on-surface chemical synthesis of molecules, as well as the construction of atomic wires on selected surfaces is applied. Polycyclic aromatic hydrocarbon (PAH) molecules play a key role in this work, as they can provide the functionality of the molecular scale devices. In the first part of this work, I investigate different PAH´s on the Au(111) surface. The precursor molecules form supramolecular assemblies and the on-surface synthesis approach to obtain the desired molecular products is used. In particular, bisanthene molecules via a cyclodehydrogenation reaction and the non-alternant polyaromatic hydrocarbon diindenopyrene after a thermally induced debromination followed by selective ring-closure to form a five-membered ring are obtained. An interesting surface for future applications is the passivated silicon Si(001)-(2x1):H. I prepare this surface and characterize the substrate. The surface has a band gap and molecules are electronically decoupled from the semiconducting substrate due to the passivation layer. Furthermore, atomic defects on this substrate, so called dangling bonds (DB´s), have defined electronic states. I show that it is possible to produce DB defects controllably by applying voltage pulses using the tip of the STM and achieve with this method atomic wires with DB´s. The third part of this thesis deals with the investigation of molecular structures on Si(001)-(2x1):H. I present the generation of hexacene by a surface assisted reduction. This result can be generalized for the generation of PAH´s after deoxygenation on passivated silicon and can open new routes to design functional molecules on this substrate. Secondly, one-dimensional chains of acetylbiphenyl (ABP) molecules are explored. They interact via its pi-stacked phenyl rings that are considered as conducting channel. Finally, I demonstrate that a single ABP molecule acts as a switch, as one can reversibly passivate and depassivate a single DB by a hydrogen transfer. In the last part of this work, I test the new low-temperature four-probe STM located at CEMES-CNRS in Toulouse. This machine is constructed for the development of molecular scale devices. For this purposes an atomic precision is needed for all the different tips at the same time and a high stability of this scanning probe microscope must be achieved. I perform a manipulation experiment of molecules to test the necessary submolecular precision. For that reason, supramolecular assemblies of ABP molecules on Au(111) are imaged and manipulated by any of the four tips using the lateral manipulation mode as well as by voltage pulses. The stability of the system is shown, as all tips of the four-probe STM work independently in parallel.:1 Introduction 2 Fundamentals of scanning tunneling microscopy 2.1 The working principle 2.2 Scanning tunneling spectroscopy 2.3 Manipulation modes 2.4 Modeling 3 Experimental setup, materials and methods 3.1 The scanning tunneling microscope 3.2 The Au(111) surface 3.3 Further experimental details 4 On-surface synthesis of molecules 4.1 Introduction 4.2 Generation of a periacene 4.3 Investigating a non-alternant PAH 4.4 Conclusion 5 The passivated silicon surface 5.1 Introduction 5.2 Preparation of passivated silicon 5.3 Characterization of Si(001)-(2x1):H 5.4 Tip-induced formation of dangling bonds 5.5 Conclusion 6 Organic molecules on passivated silicon 6.1 Introduction 6.2 Hexacene generated on passivated silicon 6.3 Acetylbiphenyl on passivated silicon 6.4 Conclusion 7 Testing a low temperature four-probe STM 7.1 Introduction 7.2 The four-probe STM 7.3 Performance test of the four-probe STM on Au(111) 7.4 Manipulation of ABP assemblies 7.5 Conclusion 8 Summary and outlook 9 Appendix 9.1 Dibromo-dimethyl-naphtalene on Au(111) 9.2 Epiminotetracene on Au(111) Bibliography Curriculum vitae Scientific contributions Acknowledgement Statement of authorship / In dieser Arbeit untersuche ich Modellsysteme für planare atomare und molekulare Elektronik auf Oberflächen. Die Systeme auf der Nanoskala werden experimentell durch die Kombination aus Rastertunnelmikroskopie (RTM) und atomarer sowie molekularer Manipulation untersucht. Moleküle werden durch die oberflächenchemische Synthese generiert und atomare Drähte auf ausgewählten Oberflächen hergestellt. Polyzyklisch aromatische Kohlenwasserstoff (PAK) Moleküle spielen bei dieser Arbeit eine Schlüsselrolle, da sie die passiven und aktiven Elemente auf molekularem Maßstab darstellen können. Im ersten Teil dieser Arbeit untersuche ich verschiedene PAK´s auf der Au(111)-Oberfläche. Die Präkursoren bilden dabei supramolekulare Anordnungen und ich nutze die Oberflächensynthese, um die gewünschten molekulare Produkte zu erhalten. Im Speziellen habe ich Bisanthen-Moleküle über eine Zyklodehydrogenationsreaktion und das nicht-alternierende PAK Diindenopyren erzeugt. Dieses entsteht nach einer thermisch-induzierten Debromierung gefolgt von selektivem Ringschluss, sodass ein fünfgliedriger Ring gebildet wird. Eine interessante Oberfläche für zukünftige Anwendungen ist das passivierte Silizium Si(001)-(2x1):H. Ich habe diese Oberfläche erfolgreich präpariert und das Substrat charakterisiert. Die Oberfläche hat eine Bandlücke und Moleküle sind elektronisch von dem halbleitenden Substrat durch die Passivierungsschicht entkoppelt. Desweiteren haben atomare Defekte dieser Oberfläche, sogenannte Dangling-Bond´s (DB’s), definierte elektronische Zustände innerhalb der Bandlücke. Ich habe DB´s kontrolliert durch Spannungspulse mithilfe der Spitze des RTM erzeugt und stelle so atomare Drähte mit DB Defekten her. Der dritte Teil dieser Arbeit befasst sich mit der Untersuchung molekularer Strukturen auf Si(001)-(2x1):H. Die Erzeugung von Hexacen auf passivierten Silizium durch eine oberflächenunterstützte Reduktion wird gezeigt. Dieses Ergebnis ist eine neue Strategie für die Herstellung von PAK´s nach der Deoxygenierung und eröffnet neue Wege um funktionelle Moleküle auf diesem Substrat zu entwerfen. Zweitens zeige ich, dass Acetylbiphenyl (ABP) Moleküle eindimensionale Ketten auf dieser Oberfläche bilden. Diese interagieren über ihre Phenylringe, welche als leitender Kanal gesehen werden können. Zudem kann ein einzelnes ABP Molekül wie ein Schalter genutzt werden, da es reversibel einzelne DB´s durch Wasserstoffübertragung passivieren und depassivieren kann. Im letzten Teil dieser Arbeit wird das neue Tieftemperatur Vier-Sonden RTM, welches sich in CEMES-CNRS in Toulouse befindet, getestet. Diese Maschine ist für die Herstellung und Untersuchung von Geräten im molekularem Maßstab konstruiert worden. Zu diesem Zweck ist eine atomare Präzision für die verschiedenen Spitzen zur gleichen Zeit erforderlich und eine hohe Stabilität des Rastersondenmikroskops muss gewährleistet sein. Ich führe ein Manipulationsversuch an Molekülen durch, um die notwendige submolekulare Präzision zu testen. Dafür werden supramolekulare Anordnungen von ABP-Molekülen auf Au(111) abgebildet und die Strukturen mit jeder der vier Spitzen im lateralen Manipulationsmodus und durch Spannungpulse bewegt. Damit habe ich die Stabilität des Systems getestet und konnte zeigen, dass alle Spitzen des Systems unabhängig voneinander parallel arbeiten.:1 Introduction 2 Fundamentals of scanning tunneling microscopy 2.1 The working principle 2.2 Scanning tunneling spectroscopy 2.3 Manipulation modes 2.4 Modeling 3 Experimental setup, materials and methods 3.1 The scanning tunneling microscope 3.2 The Au(111) surface 3.3 Further experimental details 4 On-surface synthesis of molecules 4.1 Introduction 4.2 Generation of a periacene 4.3 Investigating a non-alternant PAH 4.4 Conclusion 5 The passivated silicon surface 5.1 Introduction 5.2 Preparation of passivated silicon 5.3 Characterization of Si(001)-(2x1):H 5.4 Tip-induced formation of dangling bonds 5.5 Conclusion 6 Organic molecules on passivated silicon 6.1 Introduction 6.2 Hexacene generated on passivated silicon 6.3 Acetylbiphenyl on passivated silicon 6.4 Conclusion 7 Testing a low temperature four-probe STM 7.1 Introduction 7.2 The four-probe STM 7.3 Performance test of the four-probe STM on Au(111) 7.4 Manipulation of ABP assemblies 7.5 Conclusion 8 Summary and outlook 9 Appendix 9.1 Dibromo-dimethyl-naphtalene on Au(111) 9.2 Epiminotetracene on Au(111) Bibliography Curriculum vitae Scientific contributions Acknowledgement Statement of authorship

<p>U ovoj doktorskoj disertaciji predstavljena je radiolo&scaron;ka i strukturna karakterizacija građevinskih materijala koji se mogu naći u upotrebi u Srbiji. Izvr&scaron;ena je radiolo&scaron;ka karakterizaicija ukupno 348 uzoraka: granita,&nbsp; fosfogipsa,&nbsp; sirovina&nbsp; u&nbsp; keramičkoj&nbsp; industriji,&nbsp; keramičkih pločica,&nbsp; betona,&nbsp; opeke,&nbsp; maltera,&nbsp; siporeksa,&nbsp; crepa&nbsp; i&nbsp; drugih<br />građevinskih materijala op&scaron;te upotrebe.&nbsp; Radiolo&scaron;ka karakterizacija je&nbsp; sprovedena&nbsp; merenjem&nbsp; koncentracija&nbsp; aktivnosti 226 Ra,232 Th&nbsp; i 40 K metodom&nbsp; gama&nbsp; spektrometrije,&nbsp; kao&nbsp; i&nbsp; ekshalacije&nbsp; radona&nbsp; iz selektovanih&nbsp; građevinskih&nbsp; materijala&nbsp; kori&scaron;ćenjem&nbsp; aktivnih&nbsp; uređaja RAD7,&nbsp; RTM&nbsp; 1688-2,&nbsp; AlphaGUard&nbsp; i&nbsp; AlphaE.&nbsp; Kori&scaron;ćenjem&nbsp; Monte Karlo&nbsp; simulacija&nbsp; izvr&scaron;ena&nbsp; je&nbsp; procena&nbsp; jačina&nbsp; apsorbovanih&nbsp; doza<br />gama&nbsp; zračenja,&nbsp; uočena&nbsp; su&nbsp; odstupanja&nbsp; od&nbsp; teorijski&nbsp; procenjenih vrednosti&nbsp; i&nbsp; dati&nbsp; predlozi&nbsp; za&nbsp; korekciju.&nbsp; Izvr&scaron;ena&nbsp; je&nbsp; procena radijacionog&nbsp; rizika&nbsp; od&nbsp; kori&scaron;ćenja&nbsp; analiziranih&nbsp; građevinskih materijala&nbsp; u&nbsp; enterijeru,&nbsp; kao&nbsp; i&nbsp; za&nbsp; profesionalna&nbsp; lica&nbsp; pri&nbsp; radu&nbsp; sa sirovinskim&nbsp; materijalima.&nbsp; Ispitivane&nbsp; su&nbsp; mogućnosti&nbsp; upotrebe fosfogipsa&nbsp; kao&nbsp; NORM&nbsp; materijala&nbsp; u&nbsp; proizvodnji gips-karton&nbsp; ploča&nbsp; i opeke&nbsp; uz procenu radijacionog rizika od upotrebe.&nbsp; Napravljeno je 8 uzoraka&nbsp; opeke&nbsp; sa&nbsp; različitim&nbsp; udelog&nbsp; fosfogipsa&nbsp; i&nbsp; izvr&scaron;ena&nbsp; je<br />radiolo&scaron;ka&nbsp; i&nbsp; strukturna&nbsp; karakterizacija&nbsp; dobijenih&nbsp; materijala. Ispitivane&nbsp; su&nbsp; varijacije&nbsp; koeficijenata&nbsp; emanacije&nbsp; radona&nbsp; iz građevinskih materijala tokom vremena, kao i uticaj efekata curenja i povratne difuzije koji dovode do tih varijacija. Ispitivan je takođe i uticaj strukture materijala u smislu mineralo&scaron;kog i hemijskog satava i&nbsp; poroznosti&nbsp; na&nbsp; vrednosti&nbsp; koeficijenta&nbsp; emanacije&nbsp; radona. Meneralo&scaron;ka&nbsp; karakterizacija&nbsp; uzoraka&nbsp; izvr&scaron;ena&nbsp; je&nbsp; metodom rendgenske&nbsp; strukturne&nbsp; analize&nbsp; (XRD),&nbsp; a&nbsp; hemijska&nbsp; metodom rendgenske&nbsp; fluorescentne&nbsp; analize&nbsp; (XRF).&nbsp; Merenje&nbsp; ukupne&nbsp; efektivne poroznosti izvr&scaron;eno je metodama apsorpcije vode i metodom živine porozimetrije.&nbsp; Na&nbsp; osnovu&nbsp; dobijenih&nbsp; rezultata&nbsp; uspostavljene&nbsp; su značajne&nbsp; korelacije&nbsp; između&nbsp; pojedinih&nbsp; radiolo&scaron;kih&nbsp; i&nbsp; strukturnih parametara za analizirane uzorke građevinskih materijala.</p> / <p>In&nbsp; this&nbsp; doctoral&nbsp; dissertation,&nbsp; the&nbsp; results&nbsp; of&nbsp; the&nbsp; radiological&nbsp; and structural characterization of building materials used in Serbia were presented.&nbsp; Radiological&nbsp; characterization&nbsp; of&nbsp; a&nbsp; total&nbsp; of&nbsp; 348&nbsp; samples was performed, including granite, phosphogypsum, raw&nbsp; materials&nbsp; in the ceramic industry, ceramic tiles, concrete, brick, mortar, siporex, tiles,&nbsp; and&nbsp; other&nbsp; materials&nbsp; frequently&nbsp; used&nbsp; as&nbsp; building&nbsp; materials.Radiological characterization was performed by measuring activity concentrations&nbsp; of 226 Ra,232 Th,&nbsp; and 40 K&nbsp; by&nbsp; gamma&nbsp; spectrometry method, as well&nbsp; as radon exhalation from selected building materials using active devices RAD7, RTM 1688-2, AlphaGuard and AlphaE.Using&nbsp; Monte&nbsp; Carlo&nbsp; simulations,&nbsp; the&nbsp; absorbed&nbsp; gamma&nbsp; dose&nbsp; rates were&nbsp; estimated.&nbsp; Furthermore,&nbsp; the&nbsp; deviations&nbsp; from&nbsp; the&nbsp; theoretically estimated&nbsp; absorbed&nbsp; dose&nbsp; rates&nbsp; were&nbsp; observed,&nbsp; and&nbsp; suggestions&nbsp; for correction were given. An assessment of the radiation risk from the use&nbsp; of&nbsp; analyzed&nbsp; building&nbsp; materials&nbsp; in&nbsp; the&nbsp; interior,&nbsp; as&nbsp; well&nbsp; as&nbsp; for occupational&nbsp; workers&nbsp; working&nbsp; with&nbsp; raw&nbsp; materials&nbsp; was&nbsp; conducted.The possibilities of using phosphogypsum as a NORM material in the production&nbsp; of&nbsp; gypsum&nbsp; plasterboard&nbsp; and&nbsp; bricks&nbsp; were&nbsp; investigated, with&nbsp; an&nbsp; assessment&nbsp; of&nbsp; the&nbsp; radiation&nbsp; risk&nbsp; due&nbsp; to&nbsp; use&nbsp; of&nbsp; phosphogypsum as a component in the building materials. 8 samples of&nbsp; bricks&nbsp; with&nbsp; different&nbsp; proportions&nbsp; of&nbsp; phosphogypsum&nbsp; were&nbsp; made and&nbsp; radiological&nbsp; and&nbsp; structural&nbsp; characterization&nbsp; of&nbsp; the&nbsp; obtained materials was performed. Variations of radon emanation coefficients from building materials over time, as well as the influence of leakage and&nbsp; back&nbsp; diffusion&nbsp; effects&nbsp; leading&nbsp; to&nbsp; these&nbsp; variations,&nbsp; were investigated. The influence of the structure of the material in terms of mineral and chemical composition and porosity on the values of the radon&nbsp; emanation&nbsp; coefficient&nbsp; was&nbsp; also&nbsp; investigated.&nbsp; The mineralogical characterization of the samples was performed by the method&nbsp; of&nbsp; X-ray&nbsp; structural&nbsp; analysis&nbsp; (XRD),&nbsp; and&nbsp; the&nbsp; chemical characterization&nbsp; by&nbsp; the&nbsp; method&nbsp; of&nbsp; X-ray&nbsp; fluorescence&nbsp; analysis (XRF). The measurement of total effective porosity was performed by water absorption methods and mercury porosimetry method. Based on&nbsp; the&nbsp; obtained&nbsp; results,&nbsp; significant&nbsp; correlations&nbsp; were&nbsp; establishedbetween&nbsp; individual&nbsp; radiological&nbsp; and&nbsp; structural&nbsp; parameters&nbsp; for&nbsp; the analyzed samples of construction materials.</p>

<p dir="ltr">The manufacturing of composite materials presents numerous opportunities due to their superior properties, including high strength-to-weight ratios and excellent fatigue resistance, which make them ideal for advanced engineering applications. However, realizing these advantages is challenging due to complexities in manufacturing processes, which can introduce defects, residual stress, and variability. This study aims to address these challenges through the development of integrated, physics-based processing models that are capable of predicting and mitigating manufacturing defects in advanced composites. The research focuses on the integration of these physics-based models with data-driven methods such as statistical analysis, uncertainty quantification, and optimization. A significant emphasis is placed on modeling the thermo-viscoelastic (TVE) behavior of curing composites, which is often simplified in processing simulations due to computational costs, by approximating to elastic responses according to the Cure Hardening Instantaneously Linear Elastic (CHILE) model. Results show that cure-dependent TVE process simulations implemented through Finite Element Analysis (FEA) can be efficiently integrated with optimization algorithms. 570 simulations completed in 109 min on a local desktop computer. Building on these advancements, this work further investigates Automated Fiber Placement (AFP) under the context of Integrated Computational Materials Engineering (ICME), and establishes the groundwork and serves as roadmap for AFP research at Purdue University with a focus on process modeling and integration.</p>

Dans ce manuscrit, un modèle complet pour la simulation de l'écoulement d'un fluide thermor éactif à travers un milieu poreux fortement compressible est présenté. Ce modèle est utilisé pour l'étude des procédés d'élaboration des matériaux composites par infusion à travers leur épaisseur (Liquid Resin Infusion-LRI et Resin Film Infusion-RFI ). Dans ces procédés, le mélange entre les renforts et la résine liquide est réalisé dans la direction transverse aux plans des préformes pendant la phase de mise en forme. Les coˆuts sont ainsi réduits et les problèmes de remplissage éliminés. Ces procédés sont néanmoins peu maîtrisés et les caractéristiques de la pièce finale difficilement prévisibles (principalement les épaisseurs et les porosités). La mise au point d'un modèle numérique constituerait un bon outil pour développer et finaliser de nouvelles solutions composites. D'un point de vue physique, l'infusion de la résine à travers l'épaisseur des préformes est une conséquence de la pression appliquée sur l'empilement résine/préforme. Dans cette analyse multi-physique deux types de problèmes sont rencontrés. Tout d'abord, on connait mal les conditions de couplage entre les zones liquides, gouvernées par les équations de Stokes, et les préformes imprégnées assimilées à des milieux poreux, gouvernées par une loi de Darcy et une loi de comportement mécanique non-linéaire. Par ailleurs, les interactions entre l'écoulement de la résine et la compression des préformes ne sont pas bien maîtrisées. Le modèle développé inclut donc une condition de Beaver-Joseph- Schaffman modifiée pour le couplage entre les zones de Darcy et de Stokes. Une formulation ALE pour l'écoulement de la résine dans un milieu poreux déformable subissant de fortes déformations est utilisée et couplée à une formulation Lagrangienne Réactualisée pour la partie solide. Ces deux mécanismes physiques sont couplés à des modèles thermo-chimiques pour traiter la réticulation de la résine sous l'action du cycle de température. Dans ce travail, un certain nombre d'outils numériques et de nouvelles formulations ont été développés en vue de simuler les procédés LRI et RFI. Chaque outil est étudié et validé analytiquement ou numériquement avant d'être intégré dans les modèles LRI /RFI. Des simulations numériques d'infusion sont ensuite présentées et commentées, puis une première comparaison avec des essais expérimentaux est proposée.

Virtual tools are commonly used nowadays to optimize product design and manufacturing process of fibre reinforced composite materials. The present work focuses on two areas of interest to forecast the part performance and the production process particularities. The first part proposes a multi-physical optimization tool to support the concept stage of a composite part. The strategy is based on the strategic handling of information and, through a single control parameter, is able to evaluate the effects of design variations throughout all these steps in parallel. The second part targets the resin infusion process and the impact of thermal effects. The numerical and experimental approach allowed the identificationof improvement opportunities regarding the implementation of algorithms in commercially available simulation software. / Les eines de disseny virtual son usades de forma habitual per optimitzar el disseny i el procés productiu de peces de material compòsit reforçades amb fibra. Aquest treball es centra en dos àrees d’interès per la predicció de les prestacions de la peça i les particularitats del seu procés productiu. La primera part proposa una eina d’optimització multi-física per recolzar l’etapa de desenvolupament d’una nova peça. La estratègia es basa en la gestió intel•ligent de la informació a través d’un paràmetre de control comú, permeten l’avaluació dels canvis en totes les etapes en paral•lel. La segona part es centra en la infusió de resina, i particularment en l’impacte dels efectes tèrmics. Aquesta investigació numèrica i experimental ha permès la identificació de possibilitats de millora en la implementació d’algoritmes usats actualment en codis comercials de simulació.