This study focuses on developing novel modeling techniques for fiber-reinforced composites with polymer and ceramic matrix based on Peridynamic approach. To capture the anisotropic material behaviors of composites under quasi-static and dynamic loading conditions, a new peridynamic model for composite laminate and a modified peridynamic approach for non-uniform discretization are proposed in this study. In order to achieve the numerical implementation of the proposed model and approach, a mixed implicit-explicit solver based on GPU parallel computing is developed as well. The new peridynamic model for composite laminates does not have any limitation in fiber orientation, material properties and stacking sequence. It can capture the expected orthotropic material properties and coupling behaviors in laminates with symmetric and asymmetric layups. Unlike the previous models, the new model enables the evaluation of stress and strain fields in each ply of the laminate. Therefore, it permits the use of existing stress- or strain-based failure criteria for damage prediction. The computation of strain energy stored at material points allows the energy-based failure criteria required for delamination propagation and fatigue crack growth. The capability of this approach is verified against benchmark solutions, and validated by comparison with the available experimental results for three laminate layups with an open hole under tension and compression. The modified peridynamic approach for non-uniform discretization enables computational efficiency and removes the effect of geometric truncations in the simulation. This approach is a modification to the original peridynamic theory by splitting the strain energy associated with an interaction between two material points according to the volumetric ratio arising from the presence of non-uniform discretization and variable horizon. It also removes the requirement for correction of peridynamic material parameters due to surface effects. The accuracy of this approach is verified against the benchmark solutions, and demonstrated by considering cracking in nuclear fuel pellet subjected to a thermal load with non-uniform discretizations. Unlike the previous peridynamic simulations which primarily employs explicit algorithm, this study introduces implicit algorithm to achieve peridynamic simulation under quasi-static loading condition. The Preconditioned Conjugate Gradient (PCG) and Generalized Minimal Residual (GMRES) algorithms are implemented with GPU parallel computing technology. Circulant preconditioner provides significant acceleration in the convergence of peridynamic analyses. To predict damage evolution, the simulation is continued with standard explicit algorithms. The validity and performance of this mixed implicit-explicit solver is established and demonstrated with benchmark tests.

In der Aufbau und Verbindungstechnik von mikroelektronischen Komponenten finden vermehrt polymere Werkstoffe Einzug. Zum Beispiel wird klassisches Metalllot durch elektrisch leitfähige Klebstoffe ersetzt, beziehungsweise werden zur Fixierung von oberflächenkontaktierten elektronischen Bauelementen schnell härtende Epoxidharzklebstoffe eingesetzt. Insbesondere im automobilen Einsatzbereich werden hohe Anforderungen an die Funktionszuverlässigkeit an die elektronischen Komponenten gesetzt. Große Temperaturschwankungen sowie unterschiedlichste mechanische Lastfälle wirken auf die Elektronik ein. Die vorliegende Arbeit behandelt die Beschreibung des viskoelastischen Materialverhaltens am Beispiel eines Epoxidharzklebstoffs zur Fixierung mikroelektronischer Bauelemente in einem ausgedehnten Temperatur- und Zeitbereich. Es werden unterschiedliche experimentelle Vorgehensweisen zur Ermittlung des Relaxationsverhaltens diskutiert und eine für den großen Temperaturbereich optimierte Zeit-Temperaturverschiebung präsentiert. Die experimentellen Ergebnisse des Relaxationsverhaltens werden mittels einer Vielparameteranpassung unter Zuhilfenahme genetischer Algorithmen in ein Materialmodell übertragen. Zur Beschreibung des dreidimensionalen viskoelastischen Stoffverhaltens wird neben dem E-Modul auch die Poissonzahl mit unterschiedlichen Messmethoden in Abhängigkeit von Temperatur und Zeit untersucht. Insbesondere die berührungslose Messung von Längs- und Querdehnung im Zugrelaxationsversuch und anschließender Auswertung mittels Grauwertkorrelation wird als zielführend bewertet. Es wird ein Funktionsansatz vorgestellt, mit dem sich die Poissonzahl in Abhängigkeit von Temperatur und Zeit beschreiben lässt. Damit lässt sich das Relaxationsverhalten für sowohl den Schub- als auch dem Kompressionsmodul darstellen. Dies erhöht die Aussagegenauigkeit von numerischen Beanspruchungsanalysen und verbessert somit auch die Präzision der darauf basierenden von Lebensdauerprognosen.

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Complex moduli and Poisson’s ratio have been estimated using extensional and torsional wave experiments. The data were used for assessment of linearity and isotropy of two polymers, polymethyl methacrylate (PMMA) and polypropylene (PP). The responses of both materials were found to be close to linear and isotropic. A statistical analysis of different estimation approaches for complex modulus and Poisson’s ratio was conducted. It was shown that a joint estimation of complex modulus and Poisson’s ratio improves the estimated results. Considerable improvement was achieved in the frequency range 5-15 kHz for Poisson’s ratio. A non-equilibrium split Hopkinson pressure bar (SHPB) procedure for identification of complex modulus has been developed. Two simplified procedures were also established. Both overestimated the magnitude of the complex modulus. The complex modulus of PP was identified using PMMA and aluminium bars, and the estimated complex modulus was in good agreement with published results. The procedure was found to be accurate regardless of the specimen size or the specimen-to-bar impedance ratio. The procedure was also used to analyze the mechanical response of four compacted pharmaceutical tablet materials. A Debye-like relaxation was observed for all tested materials. Utilizing SHPB effectively requires knowledge about the impact process that is normally used for excitation. Therefore the impact between a cylindrical striker and a long cylindrical bar of viscoelastic material was studied theoretically and experimentally. Strains measured at three locations along a PMMA bar impacted by strikers of the same material agreed well with the theoretical results. A method for identification of complex shear modulus from measured shear strains on a disc subjected to a transient torque at its centre has been established. The two-dimensional wave solutions used are exact in the sense of three-dimensional theory. The results from experimental tests with different load amplitudes and durations agree well with each other.

I here present a combined AVO analysis of P-P and P-S reflection data whose objective is to improve the identification of lithology by estimating the specific values of Poisson's ratio, [sigma], for each rock formation in a given geological model, rather than a contrast between formations. Limited knowledge on the elastic parameters of a given rock formation and difficulty regarding the availability and processing of P-S data constitute hindrances of lithology identification. Considering that ocean bottom seismology (OBS) has aided in solving the problem of P-S data availability, limited information on elastic parameters is still a challenge, and the focus of this thesis. The present analysis is based on Zoeppritz' solution for the P-P and P-S reflection coefficients, RPP and RPS, with a slight modification. We used the normalized P-S reflection coefficient; i.e., R'PS = RPS / sin [theta] for [theta] > 0, instead of RPS, where [theta] is the incident angle. By normalizing RPS, we avoid dealing with the absence of converted S-waves at small incident angles and enhance the similar linear behavior of the P-P and normalized P-S reflection coefficients at small angles of incidence. We have used the linearity of RPP and R'PS at angles smaller than 35 degrees to simultaneously estimate the average VP/VS ratio, the contrasts of P- and S-wave velocities, and the contrast of density. Using this information, we solve for Poisson's ratio of each formation, which may enable lithology discrimination. The feasibility of this analysis was demonstrated using nonlinear synthetic data (i.e., finite-difference data). The results in estimating Poisson's ratio yielded less than 5 percent error. We generalize this new combined P-P and P-S AVO analysis for dipping interfaces. Similarly to the nondipping interface case, our derivations show that the amplitude variation with offset (AVO) of P-P and P-S for a dipping interface can be cast into intercepts and gradients. However, these intercepts and gradients depend on the angle of the dipping interface. Therefore, we further generalize our analysis by including a migration step that allows us to find the dipping angle. Because seismic data is not available in terms of RPP and R'PS, this process includes recovery of reflection coefficients after migrating the data and correcting for geometrical spreading, as done by Ikelle et al. (1986 and 1988). The combination of all of these steps, namely geometrical-spreading correction, migration, and AVO analysis, is another novelty of this thesis, which leads to finding the specific values of Poisson's ratio of each rock formation directly from the seismic data.

Computational models of the flow-induced vibrations of the vocal folds are powerful tools that can be used in conjunction with physical experiments to better understand voice production. This thesis research has been performed to contribute to the understanding of vocal fold dynamics as well as several aspects of computational modeling of the vocal folds. In particular, the effects of supraglottal geometry have been analyzed using a computational model of the vocal folds and laryngeal airway. In addition, three important computational modeling parameters (contact line location, Poisson's ratio, and symmetry assumptions) have been systematically varied to determine their influence on model output. Variations in model response were quantified by comparing glottal width, frequency, flow rate, open quotient, pressures, and wave velocity measures. In addition, the glottal jet was qualitatively analyzed. It was found that for various supraglottal geometries (either symmetrically or asymmetrically positioned), there was little asymmetry of the vocal fold motion despite significant asymmetry in the glottal jet. In addition, the vocal fold motion was most symmetric when consistent jet deflection was present (even if asymmetric). Inconsistent deflection of the glottal jet led to slightly larger asymmetries in vocal fold motion. The contact line location was found to have minimal impact on glottal width, frequency, and flow rate. The largest influence of the contact line location was seen in predicted velocity fields during the closed phase and in the pressure profiles along the vocal fold surfaces. Variations in Poisson's ratio strongly affected vocal fold motion, with lower Poisson's ratios resulting in larger amplitudes. The model did not vibrate when a Poisson's ratio of 0.49999 was used. The response of a full model (with two vocal folds) was shown to vary slightly from that of a half model (one vocal fold and a symmetry boundary condition), the greatest difference being in the deflection and dissipation of the glottal jet. It was concluded that for many scenarios the half model will be sufficient for modeling vocal fold motion; however, a full model is suggested for studies of material asymmetry or glottal jet dynamics. Application of these results to computational models of the vocal folds will lead to improved modeling and understanding of vocal fold dynamics.

Title: Methodological detection solution scaffolds response to mechanical stress, depending on the degree of hydration Objectives: Determining the extent of lateral deformation u scaffolds made of PVA polymer electrospinning technique. Identify the extent of differences in transverse deformation for different groups of nanofiber scaffolds made of PVA polymer electrospinning technique. Methods: Research scaffolds, we used a measuring device μ-tester, which has two jaws. For the measurement, we chose uniaxial tension test in -tester and record the fluorescence microscope was used with HD camera Olympus 320 for online video recording. Results: The results of this study showed that the ratio of the samples U: L and crosslinking time affects the degree of lateral deformation of the samples scaffolds. Samples scaffolds are compressible, some groups even reached the limits of incompressibility 0.5 Poisson's ratio. Keywords: Poisson, Poisson's ratio, scaffold, nanofiber scaffold, scaffold hydrated, electrospun scaffold, lateral deformation

Les enrobés bitumineux ont été utilisés habituellement dans des constructions routières et récemment sous les ballasts des ferroviaires. Sa grande rigidité aux températures relativement basses de l’ambiance et à haute fréquence explique son application répandue en Europe du nord. Ce matériau a été étudié au niveau global par à la fois des essais empiriques, expérimentaux et des approches analytiques. Pourtant, l’enrobé bitumineux possède un structure interne hétérogène et complexe qui peut-être engendrer des comportements complexe. Les analyses au niveau local permettent alors de compléter les connaissances de ses comportements.De nos jours, la méthode des éléments discrets est connue comme un outil numérique répandu dans le domaine granulaire. Elle peut modéliser son comportement à travers des modèles locaux et fournir des informations de sa structure interne. Une part, cette méthode considère que les particules sont quasi-solides. Son déplacement est régi par les lois de mouvement. L’autre part, le chevauchement au niveau de contact entre particules est admis. L’interpénétration des particules est calculée par les lois de contact locaux associées. Cette thèse constitue une maquette numérique des enrobés bitumineux dont les particules isolées s’interagissent à travers des lois d’interaction à distance. Cette maquette prend en compte la granulométrie des granulats (>1mm) et son rapport volumique vis-à-vis du mastic constitué par des grains (<1mm), le liant et des vides. Les granulats (>1mm) seuls sont modélisés par des particules numériques, tandis que du mastic est pris en compte par des lois d’interaction. Au premier lieu, une simulation élastique est réalisée afin de reproduire des comportements asymptotiques élastiques d’un enrobé bitumineux de référence de type GB3 qui apparaissent lors des conditions extrêmes (fréquence ou température). Des lois d’interaction élastiques ont appliqué à la maquette numérique créée. Sur deux directions normale et tangentielles, les raideurs du ressort et leur rapport sont constantes.Ensuite, les simulations viscoélastiques sont réalisées pour reproduire le comportement viscoélastique du même matériau de référence. Au premier temps, une loi d’interaction de type Kelvin-Voigt est utilisée pour mettre en évidence qualitativement l’application d’une loi viscoélastique. Ensuite, le comportement viscoélastique globale est modélisé à niveau des particules par quelques lois d’interaction de type 1KV1R (un Kelvin-Voigt et un ressort en série) repartant au réseau d’interaction de la maquette numérique. Les raideurs des ressorts prenant en compte la géométrie de l’interface de particules sont constantes pour toutes les modèle de 1KV1R. Cependant, des viscosités des amortisseurs sont différentes. Certaines hypothèses sont examinées pour distribuer ses viscosités dans le réseau d’interaction. A la fin des études, les analyses des efforts internes sont réalisées. / Bituminous mixtures have traditionally been used in road constructions and recently under railway ballast. Its high rigidity at relatively low ambient temperatures and high frequency explains its widespread application in northern Europe. This material has been studied at the global level by both empirical, experimental and analytical approaches. However, the asphalt has a heterogeneous internal structure and complex which may cause complex behavior. The analysis at the local level then make it possible to supplement the knowledge of its behaviors.Nowadays, the method of discrete elements is known as a numerical tool spread in the granular field. It can model its behavior through local models and provide information about its internal structure. On the one hand, this method considers that the particles are quasi-solid. Its displacement is governed by the laws of motion. On the other hand, the overlap at the particle contact level is allowed. The interpenetration of the particles is calculated by the associated local contact laws. This thesis constitutes a numerical model of bituminous mixes whose isolated particles interact through laws of interaction at a distance. This model takes into account the granulometry of the aggregates (> 1 mm) and its volume ratio with respect to the mastic constituted by grains (<1 mm), the binder and voids. The aggregates (> 1 mm) alone are modeled by numerical particles, while mastic is taken into account by laws of interaction.First, an elastic simulation is performed in order to reproduce the elastic asymptotic behaviors of a reference bituminous mix of GB3 type that appear during extreme conditions (frequency or temperature). Elastic interaction laws have applied to the created numerical model. In both normal and tangential directions, the stiffness of the spring and its ratio are constant.Then, the viscoelastic simulations are performed to reproduce the viscoelastic behavior of the same reference material. At first, a Kelvin-Voigt interaction law is used to qualitatively highlight the application of a viscoelastic law. Then, the global viscoelastic behavior is modeled at the level of the particles by some laws of interaction of type 1KV1R (a Kelvin-Voigt and a spring in series) leaving again to the network of interaction of the numerical model. The stiffness of the springs taking into account the geometry of the particle interface is constant for all models of 1KV1R. However, the viscosities of the dashpots are different. Some hypotheses are examined to distribute its viscosities in the interaction network. At the end of the studies, the analysis of the internal efforts are carried out.

Voiced communication plays a fundamental role in society. Voice research seeks to improve understanding of the fundamental physics governing voice production, with the eventual goal of improving methods to diagnose and treat voice disorders. For this thesis, three different aspects of voice production research were studied. First, porcine vocal fold medial surface geometry was determined, and the three-dimensional geometric distortion induced by freezing the larynx, especially in the region of the vocal folds, was quantified. It was found that porcine vocal folds are qualitatively geometrically similar to canine and human vocal folds, as well as commonly used models, and that freezing of tissue in the larynx causes distortion of around 5%. Second, a setup of multiple high-resolution cameras and a stereo-endoscopy system simultaneously recorded positions on the superior surface of synthetic, self-oscillating vocal fold models to estimate the error in the measurement of the three-dimensional location by the stereo-endoscopy system. The error was found to be low in the transverse plane, whereas the error was relatively large in the inferior-superior direction, suggesting that the stereo-endoscope is applicable for in vivo measurements of absolute distances of the glottis in the transverse plane such as glottal length, width, and area. Third, a function for strain-varying Poisson's ratio for silicone was developed from experimental data. It is anticipated that the findings herein can aid voice researchers as they study voice production, leading to improved voice care.