La faible densité et les propriétés mécaniques remarquables des composites polymères en font des matériaux de choix pour remplacer les métaux. Cependant, leurs propriétés physicochimiques rendent leurs surfaces peu adhésives pour divers types de revêtements. Pour améliorer l’adhérence de revêtements métalliques sur des substrats de PEEK, et pour mieux comprendre les mécanismes de l’adhésion, les propriétés de surface du matériau ont été modifiées par des procédés physiques en voie sèche.D’une part, cette étude montre que les traitements par plasma oxydants (à basse pression, ou à pression atmosphérique) permettent d’améliorer la mouillabilité de la surface et l’adhérence de revêtements métalliques, par l’augmentation de la polarité de la surface, quantifiée par XPS. D’autre part, cette étude montre que l’ablation laser infrarouge à impulsion femtoseconde permet la gravure d’un motif dense, induisant de meilleures tenues mécaniques de l’assemblage. Enfin, cette étude montre que la modification de la chimie et de la topographie combinées améliore davantage ce potentiel d’adhérence.Le but de cette étude est d’ouvrir une voie vers un modèle décrivant les mécanismes de l’adhésion, influencés par la chimie de surface et la géométrie d’un motif, en s’appuyant sur un modèle mécanique permettant de décrire la dynamique des contraintes se propageant au travers de l’interface, en tenant compte des propriétés mécaniques des matériaux. / Thanks to their low densities and good mechanical properties, polymer composites are good candidates for metal alloys substitutes. However, their physicochemical properties limit their adhesion potential towards several types of coatings. In order to improve metallic thin films adhesion on PEEK substrates, and to better comprehend adhesion mechanisms, dry-phase methods have been used to alter the surface properties of the material.First, this study shows that oxidative plasma treatments (at low or at atmospheric pressure) improve the wettability and the practical adhesion of metallic coatings, by an increase of the polar component of the surface, as measured by XPS. Second, this study shows that dense patterns etched by an infrared femtosecond laser allow good practical adhesion of the metallic thin films on the substrate. Finally, this study shows that the modification of both surface chemistry and the surface topography at the same time further improves the practical adhesion of the metallic thin films.The goal of this study is to propose a route towards a model describing the combined influence of surface texture and chemistry, with the support of a mechanical model describing the dynamics of the stress dissipation through the interface while taking into account the mechanicals properties of the interfacial materials.

In this study, an expert system based EA and tracking system is developed and the performances of these systems are optimized. Tracking system consists of a monopulse tracking radar and a Multiple Hypothesis Tracking (MHT) algorithm. MHT is modelled as a measurement&amp / #8208 / oriented approach, which is capable of initiating tracks. As each measurement is received, probabilities are calculated for the hypotheses and target states are estimated using a Kalman filter. Range Gate Pull-Off (RGPO) is selected as an EA technique to be developed because it is accepted to be the primary deception technique employed against tracking radar. Two modes of RGPO technique / linear and parabolic, according to time delay controller are modelled. Genetic Algorithm (GA) Toolbox of MATLAB is used for the optimization of these systems over some predetermined scenarios. It is observed that the performance of the tracking radar system is improved significantly and successful tracking is achieved over all given scenarios, even for closely spaced targets. RGPO models are developed against this improved tracking performance and deception of tracking radar is succeeded for all given target models.

The problem of a thin elastomeric layer confined between two stiff adherends arises in numerous applications such as microelectronics, bio-inspired adhesion and the manufacture of soft biomedical products. A common requirement is that the debonding of the elastomeric layer from the adherends be controlled to avoid undesirable failure modes. This level of control may necessitate understanding the collective role of the interfacial adhesion, material properties, part geometries, and loading conditions on the debonding. Analytical and numerical approaches using the finite element method and a cohesive zone model (CZM) for the interfacial debonding are used in this dissertation to delineate the role of the afore-mentioned parameters on the initiation and propagation of debonding for both rigid and non-rigid adherends. Extensively studied in the dissertation is the debonding of a semi-infinite relatively stiffer adherend from an elastomer layer with its other surface firmly bonded to a rigid base. The adherend is pulled upwards by applying normal displacements either on its entire unbonded surface or on the edge of its part overhanging from the elastomer layer. The adherend and the elastomeric layer materials are assumed to be linear elastic, homogeneous and isotropic and the elastomer is assumed to be incompressible. Viscoelasticity of the elastomer is considered in the first part of the work. Plane strain deformations of the system with a bilinear traction-separation (TS) relation in the CZM are analyzed. Two non-dimensional numbers, one related to the layer confinement and the other to the interfacial TS parameters, are found to determine if debonding initiates at interior points in addition to at corner points on the adherend/elastomer interface, and if adhesion-induced instability is exhibited. This work is extended to axisymmetric problems in which debonding can take place at both interfaces. Motivated by an industrial demolding problem, numerical experiments are conducted to derive insights into preferential debonding at one of the two interfaces, including for curved adherends. Results reported herein should help engineers design an elastomer layer sandwiched between two adherends for achieving desired failure characteristics. / Ph. D.

La production d’énergie avec des cellules photovoltaïques organiques (OPV) est une des applications les plus prometteuses des semi-conducteurs organiques, en raison de leur compatibilité avec les substrats flexibles permettant des produits légers, peu chers et décoratifs. Pendant longtemps, poly(3-hexylthiophène) (P3HT) a été le polymère de choix dans l’OPV combiné au [6,6]-phényl-C61-butanoate de méthyle (PC61BM) comme accepteur. Toutefois, des recherches récentes ont porté sur des polymères avec meilleures absorption et processabilité, qui peuvent assurer des rendements et des durées de vie plus élevés. Des rendements de conversion en puissance (PCE) au-dessus de 11% ont récemment été démontrés. Cette thèse rapporte sur la synthèse et la caractérisation de deux séries de polymères dits à faible bande interdite, LBGs "push-pull" (ou donneur-accepteur), constitués de l'unité donneuse 4,4-bis(2-ethylhexyl)-5,5'-dithieno[3,2-b:2',3'-d]silole (DTS) combinée au 3,6-dithiophén-2-yl-2,5-dihydro-pyrrolo[3,4-c]pyrrole-1,4-dione (DPP) ou au 5,7-di(thiényl)thiéno[3,4-b]pyrazines (DTP), comme unité acceptrice. Toutes les molécules et les polymères ont été caractérisés chimiquement et leur propriétés optoelectroniques, morphologiques et photovoltaïques ont été determinées. La série DTS-DPP a été choisie parce qu'elle est représentative d'un grand nombre de polymères LBG et a fourni un modèle facilement accessible pour évaluer l'importance de la chaîne latérale utilisée sur leur propriétés optoélectroniques et thermiques. Les premières études sur les dispositifs à base de DTS-DPP:PC61BM ont été menées, pour déterminer les propriétés photovoltaïques. Le meilleur dispositif permet d’obtenir un PCE de 1,7% avec JSC de 5,9 mA cm-2, VOC de 0,54 V et FF de 0,58. La série DTS-DTP a été choisie pour la stabilité chimique élevée des deux unités et pour la facilité de substitution des groupes latéraux. La polymérisation a partiellement abouti, en donnant seulement des oligomères. La caractérisation chimique a pu être effectuée, mais leur application dans l’OPV n'a pas été explorée. En termes de stabilité, les mécanismes de défaillance électrique des dispositifs OPV ont été étudiés, montrant une méconnaissance de leur stabilité mécanique. Les contraintes caractéristiques de chaque couche mince présentes dans les cellules solaires organiques constituent la force motrice à l’origine de la délamination des interfaces faibles ou même leur decohésion, causant une perte de l'intégrité et des performances du dispositif. Une technique pour sonder les couches ou les interfaces fragiles dans les cellules solaires polymère:fullerene est présentée. Elle a été développée par l'établissement d'un nouveau set-up pour le test pull-off, développé en utilisant un dispositif à géométrie inverse, de structure verre/ITO/ZnO/P3HT:PC61BM/PEDOT:PSS/Ag. Les dispositifs délaminés ont montré que le point le plus faible est localisé à l'interface AL/HTL, en bon accord avec la littérature. La technique a été étendue en variant les deux couches sensibles, en utilisant differents polymères LBG pour l’AL (PSBTBT et PDTSTzTz) en combinaison avec deux formulations de PEDOT:PSS, CleviosTM HTL Solar à base d'eau et un nouveau HTL Solar 2 à base de solvant organique. Une différence entre la contrainte à la rupture des dispositifs avec différentes combinaisons de AL et HTL est visible, suggérant différents chemins de fracture, tel que confirmé par la caractérisation de surface et qui pourrait être corrélée avec la différence de comportement de la couche active avec les deux formulations de PEDOT:PSS. Une autre voie adoptée, a été d’introduire une couche d’interface de copolymère à blocs amphiphile afin d'améliorer la compatibilité des deux couches. Cette stratégie n'a pas abouti et la nouvelle architecture présente une adhésion réduite. La poursuite de l’amélioration des procédés de fabrication de ces dispositifs pourrait faire de cette nouvelle architecture, une alternative viable. / Organic photovoltaic (OPV) devices are one of the most promising applications of organic semiconductors due to their compatibility with flexible plastic substrates resulting in light weight, inexpensive and decorative products. For a long time poly(3-hexylthiophene) (P3HT) has been the polymer of choice in OPV devices in combination with [6,6]-phenyl-C61-butyric acid methylester (PC61BM) as acceptor. However, recent research has focused on polymers with improved absorbance and processability that can ensure higher efficiencies and longer lifetimes (Low BandGap polymers (LBGs)). This has been fully demonstrated with a power conversion efficiency (PCE) above 11%. This thesis reports synthesis and characterization of two series of so-called “push-pull” (or donor-acceptor) LBGs based on the donor unit 4,4′-bis(2-ethylhexyl)-5,5’-dithieno[3,2-b:2′,3′-d]silole (DTS) and either 3,6-dithiophen-2-yl-2, 5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (DPP) or 5,7-di(thienyl)thieno[3,4-b]pyrazines (DTP), as acceptor unit. All π-conjugated molecules and polymers were characterized by chemical investigation and their optoelectronic, morphological, and photovoltaic properties are reported. The DTS-DPP series was chosen because representative of a large number of LBG polymers and provided an easily accessible and useful template to discover the importance of the type of side-chain used on the polymer optoelectronic and thermal properties. First studies on DTS-DPP:PC61BM devices have been conducted, in order to investigate any effect on their photovoltaic properties. The best device obtained had a PCE of 1.7% with JSC of 5.9 mA•cm-2, VOC of 0.54 V and FF of 0.58. The DTS-DTP series was chosen for the high stability of the two units and for the ease of substitution of the side-groups. The synthesis was partially successful and only oligomers were obtained. Nonetheless, chemical characterization was performed but their application in OPV was not explored. In terms of device stability, the electrical failure mechanisms in OPV devices have been investigated, while little is known about their mechanical stability. The characteristic thin film stresses of each layer present in organic solar cells, in combination with other possible fabrication, handling and operational stresses, provide the mechanical driving force for delamination of weak interfaces or even their de-cohesion, leading to a loss of device integrity and performance. A technique to probe weak layers or interfaces in inverted polymer:fullerene solar cells is presented. It was developed by establishing a new set-up for the pull-off test. The technique was developed using inverted device, with the structure glass/ITO/ZnO/P3HT:PC61BM/PEDOT:PSS/Ag. The delaminated devices showed that the weakest point was localized at the active layer/hole transporting layer interface, in good agreement with the literature. The technique was extended varying both sensitive layers, using different p-type low bandgap (co)polymers for the active layer (PSBTBT and PDTSTzTz) in combination with two different PEDOT:PSS formulations, the water based CleviosTM HTL Solar and a new organic solvent based HTL Solar 2. The half-devices produced upon destructive testing have been characterized by contact angle measurement, AFM and XPS to locate the fracture point. A difference in the stress at break for devices made with different combinations of active and hole transporting layers is visible, suggesting different fracture paths, as confirmed by surface characterization and could be correlated to the different behavior of the active layer with the two PEDOT:PSS formulations. Another solution adopted, it had been the introduction of amphiphilic block-copolymer interlayer to enhance the compatibility of the two layers. This strategy was not successful and the new architecture showed reduced adhesion strength. Further development of device processing could make this new architecture a viable alternative.

This diploma thesis deals with various procedures of surface pretreatment of steel and aluminum alloy for subsequent application of powder coating substance. The work begins with an overview of the general characteristics of the materials used. The core part of the work is then a summary of the individual methods of pretreatment that can be used to modify the material surface. A special chapter is devoted to methodologies for the application of powder substances. Before separate application, the sample must first be carefully pretreated to ensure removal of organic compounds (e.g. oils from primary processing - grinding, cutting), or dust impurities to ensure the correct barrier effect. After dividing the individual methods of surface preparation, a powder paint system with a total thickness of approximately 50 µm is applied to the test material. Samples with different surface pretreatments will be compared both in terms of mechanical properties and in terms of electrochemical properties.

The adhesive and frictional response of an AFM tip connected to a substrate through supramolecular host–guest complexes is investigated by dynamic Monte Carlo simulations. Here, the variation of the pull-off force with the unloading rate recently observed in experiments is unraveled by evidencing simultaneous (progressive) breaking of the bonds at fast (slow) rates. The model reveals the origin of the observed plateaus in the retraction force as a function of the tip-surface distance, showing that they result from the tip geometrical features. In lateral sliding, the model exhibits a wide range of dynamic behaviors ranging from smooth sliding to stick-slip at different velocities, with the average friction force determined by the characteristic formation/rupture rates of the complexes. In particular, it is shown that for some molecular complexes friction can become almost constant over a wide range of velocities. Also, we show the possibility of exploiting the ageing effect through slide-hold-slide experiments, in order to infer the characteristic formation rate. Finally, our model predicts a novel ‘‘antiageing’’ effect which is characterized by a decrease of the static friction force with the hold time. Such an effect is explained in terms of enhancement of adhesion during sliding, especially observed at high driving velocities.

This thesis deals with the diagnosis of a residential building from the late nineteen twenties for the needs of reconstruction. The methods generally used in the diagnosis of structures are briefly described in the theoretical part. More deeply this section describes the methods that were used during this particular research. The practical part deals with the diagnosis of the object itself. The first section describes the layout of the villa, its design solution, its faults and defects detected during the inspection. The next section deals with evaluating the current state of construction materials. Static reports of several structural parts were calculated in the last section.