Indiana University-Purdue University Indianapolis (IUPUI) / Clinical evidence suggests that the use of liners in posterior composite restorations may increase the frequency of restoration fractures. Materials that have been used as liner materials for resin composite (RC) restoration include conventional glass ionomers, resin-modified glass ionomers (RMGI), and flowable composites. The aim of this study was to compare the flexural strength of a monolayer of resin composite with that of a bilayer of resin composite and liner. Four types of RC beams were tested: a monolayer control that is an un-lined RC (Tetric EvoCeram, Ivoclar Vivadent) and three “bilayer” specimens that consisted of this same RC lined with one of three liners. The three liners used included two RMGI cements (Vitrebond LC liner; 3M ESPE and, GC Fuji Lining LC; GC America) and a flowable resin composite (Tetric EvoFlow, Ivoclar Vivadent). Each group was tested after water storage for 24 h and 30 d. Altogether, eight, 12-specimen groups were fabricated and tested. Methods: A 25 x 2 x 2 mm mold was completely filled with the RC to form the control beams. To form the bilayer beams, this mold was filled with 0.5 mm of the liner and then with 1.5 mm of the RC. Specimens were stored in 37oC distilled for either 24 h or 30 d. Immediately prior to testing, the 30-day groups were also thermocycled 2500 times, between water baths at 7 oC and 48oC with a 30-s dwell time and a 10-s transit time. Flexural strength was determined using a three-point–bending device. A twoway analysis of variance (ANOVA) with interactions was used to investigate how liner group (or no liner) and storage time affected strength. Results: The interaction between liner type and storage time was significant (p = 0.0128). The un-lined RC (the monolayer beam) was significantly stronger after 24 h than after 30 d in water (p = 0.0098). Water storage between 24 h and 30 d did not change the flexural strength of any of the bilayer (lined) beams (p > 0.05). After storage for 24 h and also for storage for 30 d, both un-lined RC and RC lined with the flowable RC exhibited significantly higher flexural strength (p = 0.0001) than the bilayer beams lined with either RMGI liners.

Understanding the behavior of charring or decomposing materials exposed to high temperature environments is an essential aspect in rocket design. In particular, the tip of re-entry vehicles and sacrificial rocket nozzle liners are both exposed to extremely high temperatures. This thesis is specifically concerned with better understanding the reaction of sacrificial rocket nozzle liners to these high temperature environments. The sacrificial liners are designed to shield the rocket nozzle from the thermal and chemical effects of the heated exhaust gas that flows through the nozzle. However, in the design process space and weight of the rocket are at a premium. The sacrificial liners need to be designed to be as light and thin as possible, while properly shielding the nozzle from the heated exhaust gases. The sacrificial liner material is initially impermeable in its virgin state; however, as the liner is exposed to the heated exhaust gases, it chars and the liner material begins to decompose. The decomposition of the liner by heating in the absence of oxygen is known as pyrolysis. At high temperatures, the virgin material will decompose into a solid material (charred liner) and a vapor (pyrolysis gas). The pyrolysis process leads to the flow of pyrolysis gases throughout the porous charred liner. As a result, significant pressures can build within the liner. If the pressures within the liner are high enough, mechanically weak portions of the liner may fracture and break off. Fracturing of the liner could expose the nozzle to the heated exhaust gases, thus jeopardizing the structural integrity of the nozzle. Therefore, it is important to understand the pressure distribution within the sacrificial liners that occurs as a result of the pyrolysis process. This work describes the code PorePress, which solves for steady state and transient pressure distributions in 1- and 2-D axisymmetric geometries that represent sacrificial liners. The PorePress code is essentially a 1- and 2-dimensional differential equation solver for mixed, unstructured geometries. Specifically, the code is used for solving a coupled form of the Ideal Gas Law, Conservation of Mass, and Conservation of Momentum Equations, which describe the flow and resulting pressures within liner geometries. The code centers around using Taylor Series expansions to approximate derivatives needed to solve the appropriate differential equations. The derivative approximation process used in PorePress is grid transparent, meaning the same method can be used for any combination of quadrilateral (4-sided) or triangular (3-sided) elements in a mesh, without any changes to the code. Stability issues arise in both the 1- and 2-D PorePress solution processes, as a result of the non-linear nature of the coupled equations, high spatial gradients, and large variations in material properties. In the 1-D case stabilization techniques such as: upwinding, dynamic differencing, under-relaxation, and preconditioning are applied. Meanwhile, in the 2-D case, stabilization techniques such as: inverse weighting and QR factorization of the coefficient matrix, under-relaxation, and preconditioning are applied. The steady state and transient solution processes for both the 1- and 2-D pore pressure solution processes used in PorePress are covered in this thesis, as well as discussion of the resulting pressure distributions. Certain sacrificial liner design considerations that arise as a result of PorePress models for sample liner burns are also covered. / Master of Science

In this research an innovative combination of the Herschel-Quincke tubes and traditional liners is proposed for application in noise reduction of aircraft engines. The approach consists of installing Herschel-Quincke (HQ) tubes on lined rectangular ducts. An analytical model was developed to predict the effects of HQ tubes applied to rectangular lined ducts. The technique involves assuming the tube-duct interfaces as finite piston sources. These sources couple the acoustic field inside the duct with the acoustic field within the HQ tubes. The accuracy of the analytical model was validated with experimental data. Three different types of experimental configurations were tested: liner only, HQ tube with a hard wall duct, and HQ tubes with liners. Analytical predictions were shown to correlate well with the experimental data. Two typical types of liners, perforate and linear, were tested in these investigations. The perforate and linear liners with HQ systems showed better sound attenuations than the HQ tubes with hard walled ducts and liners only systems. The performance of the perforate and linear liners with HQ tubes were investigated in various configurations. The results indicated possible combinations which show great potential for reducing the noise within the ducts. / Master of Science

Mistura compactada de materiais inconsolidados das formações Serra Geral e Botucatu foram percoladas por soluções com diversas concentrações de K+, Cl- e Cu++, em testes de coluna, para a avaliar a potencialidade da sua utilização como liner. Na modelagem dos resultados adotaram-se resoluções analíticas e semi-analíticas (programa POLLUTE v6). Estudo complementar sobre o comportamento eletroquímico destes solos foi realizado pelos ensaios de titulação potenciométrica, capacidade de tamponamento, pH em água e KCI, CTC e análise mineralógica por difração de Raios-X e térmica diferencial. Os resultados mostraram uma forte influência das características da carga elétrica superficial do solo no comportamento competitivo dos íons. / A compacted mixture of soils from Serra Geral and Botucatu formations were percolated by chemical solutions with several concentrations of K+, Cu++ e Cl-, in column tests, in order to assess the potential of this mixture as a liner-building material. In the modeling procedures for the results, analytical and semi-analytical solutions (POLLUTE v.6 software) were used. Additional studies about the electrochemical behavior of these soils were performed, using potenciometric titration, soil buffer capacity, pH in water and KCI and mineralogical assessment by X-Ray Diffraction and differential thermal analysis. The results showed a very strong influence of the soil superficial charge in the competitive ion behavior.

Les travaux de thèse gravitent autour de la thématique des matériaux poreux en aéronautique, et de la prise en compte de l'incertitude sur les caractérisations réalisées. Est envisagé l'ajout de matériaux poreux au sein des cavités de liners acoustiques, matériaux constitués d'une plaque perforée et d'une cavité fonctionnant sur le principe du résonateur de Helmholtz et majoritairement utilisés dans l'industrie aéronautique. Cet ajout est réalisé avec pour objectif d'augmenter l'étendue spectrale de l'absorption acoustique de tels matériaux et d'en améliorer le fonctionnement en présence d'un fort niveau sonore et d'un écoulement rasant.Pour répondre à cette problématique générale, deux grandes pistes sont suivies. Plusieurs études sont d'abord menées sur des matériaux poreux seuls, afin de déterminer les propriétés intrinsèques de leur micro-géométrie, nécessaires à l'utilisation des modèles semi-phénoménologiques de fluide équivalent adoptés par la suite. Pour cela, un outil statistique d'inférence Bayésienne est utilisé afin d'extraire l'information sur ces propriétés, contenue dans les signaux réfléchis ou transmis par un matériau poreux, et ce dans trois régimes fréquentiels distincts. De plus, une extension de la modélisation des matériaux poreux rigides est proposée, par l'ajout de deux paramètres intrinsèques reliés au comportement visco-inertiel du fluide intra-pores dans le régime des basses fréquences.Dans un second temps, l'impédance d'un liner, une propriété globale représentant le comportement acoustique de matériaux, est identifiée par inférence Bayésienne. Des données issues d'un benchmark de la NASA sont utilisées pour valider l'outil d'inférence développé, lorsque le matériau est en présence d'un écoulement rasant. Une extension des résultats au cas du banc B2A de l'ONERA est également réalisée, avec des mesures des champs de vitesses au dessus du liner, obtenues par LDV. Cette technique d'identification est par la suite utilisée sur un cas issu du B2A où un matériau poreux est présent au sein des cavités du liner, afin de mettre à jour l'influence du matériau poreux sur la réponse acoustique du liner en présence d'un écoulement rasant. Des mesures complémentaires en tube à impédance, sans écoulement et en incidence normale, sont également réalisées à différents niveaux sonores et pour diverses combinaisons de plaques perforées et de matériaux poreux, de façon à mettre en évidence l'influence de la présence d'un matériau poreux sur le comportement acoustique d'un liner soumis à de forts niveaux sonores. / The present work focuses on porous materials in aeronautics and the uncertainty considerations on the performed identifications. Porous materials are added inside the cavities of acoustic liners, materials formed with perforated plates and cavities, behaving as Helmholtz resonators, which are widely used in the industry. The aim is to increase the frequency range of the absorption spectrum, while improving the behaviour of liners to grazing flow and high sound intensity.This general topic is addressed by following two different leads.Porous materials were first considered in order to identify the intrinsic properties of their micro-geometry, necessary to the equivalent fluid semi-phenomenological models used later on. To achieve this, a statistical Bayesian inference tool is used to extract information on these properties, contained in reflected or transmitted signals, in three distinct frequency regimes. Furthermore, a modelling extension of rigid porous media is introduced, by adding two new intrinsic parameters related to the pore micro-structure and linked to the visco-inertial behaviour of the intra-pore fluid, at low frequencies.Then, the liner impedance, a global property representing the acoustic behaviour of materials, is identified through a Bayesian inference process. Data from a NASA benchmark are used to validate the developed tool, when the liner is subject to a shear grazing flow. An extension of these results to ONERA's B2A aeroacoustic bench is also performed, with measurements of the velocity profiles above the liner, obtained with a Laser Doppler Velocimetry technique. This identification technique is then further used for liner materials filled with porous media, to highlight the eventual influence of such a porous media on the acoustic response of the liner, when subject to a shear grazing flow. Additional measurements are permed without flow, at normal incidence, in a classical impedance tube. Different combinations of perforated plates and porous materials are tested at different sound pressure level, to evaluate the influence of the presence of porous media on the non-linear behaviour of liners when high sound pressure levels are present.

Mistura compactada de materiais inconsolidados das formações Serra Geral e Botucatu foram percoladas por soluções com diversas concentrações de K+, Cl- e Cu++, em testes de coluna, para a avaliar a potencialidade da sua utilização como liner. Na modelagem dos resultados adotaram-se resoluções analíticas e semi-analíticas (programa POLLUTE v6). Estudo complementar sobre o comportamento eletroquímico destes solos foi realizado pelos ensaios de titulação potenciométrica, capacidade de tamponamento, pH em água e KCI, CTC e análise mineralógica por difração de Raios-X e térmica diferencial. Os resultados mostraram uma forte influência das características da carga elétrica superficial do solo no comportamento competitivo dos íons. / A compacted mixture of soils from Serra Geral and Botucatu formations were percolated by chemical solutions with several concentrations of K+, Cu++ e Cl-, in column tests, in order to assess the potential of this mixture as a liner-building material. In the modeling procedures for the results, analytical and semi-analytical solutions (POLLUTE v.6 software) were used. Additional studies about the electrochemical behavior of these soils were performed, using potenciometric titration, soil buffer capacity, pH in water and KCI and mineralogical assessment by X-Ray Diffraction and differential thermal analysis. The results showed a very strong influence of the soil superficial charge in the competitive ion behavior.

Cette thèse se situe dans le cadre du projet FRESCORT (Futur REservoir à Structure COmposite de Rupture Technologique) qui a but le développement de réservoirs haute pression en matériau composite bobiné. Le liner de ces réservoirs se composent d'une partie en titane T35 de 300µm d'épaisseur et d'embouts en TA6V. Le présent travail est consacré à l'étude de la microstructure et des propriétés mécaniques du titane T35 ainsi qu'à la modélisation du comportement observé. Il apparait que le titane T35 et le TA6V ont des microstructures et des compositions chimiques très différentes. De plus, dans les zones soudées entre le T35 et le TA6V, des cavités sont observées. Ces cavités semblent dues à la vaporisation de l'aluminium présent dans le TA6V durant l'opération de soudage. Le comportement mécanique du titane T35 est décrit à l'aide d'essais de traction monotone, de traction/relaxation et de cisaillement monotone et cyclique. Ces essais ont mis en évidence un comportement élasto-viscoplastique anisotrope du titane T35, avec la présence d'un écrouissage isotrope négatif. La modélisation de ce comportement mécanique et l'identification des paramètres associés, utilisent la base de donnes expérimentales obtenues précédemment. Il est montré qu'un modèle anisotrope avec un écrouissage isotrope+cinématique permet de décrire précisément à la fois l'anisotropie de chargement et de déformation, le comportement cyclique de cisaillement et le comportement plastique pour des niveaux de déformation plastique pouvant atteindre 50%. Enfin, la rupture des tôles de titane T35 est étudié. Une propagation stable avec une forte déformation plastique en pointe de fissure est trouvé. Diverses observations par tomographie et laminographie montrent la présence de peu de cavités à proximité des fissures, ce qui indique qu'il y a peu d'endommagement lors de la propagation. / This thesis is a part of the FRESCORT project whose purpose is to develop high pressure tanks in composite material. The metallic liner of these tanks consist of a sheet of 300µm thick and of TA6V nozzles. The present work is dedicated to the study of the microstructure, of the mechanical properties and of the modeling of the observed behavior. It appears that the T35 and the TA6V have very different microstructure and chemical compositions. Moreover, in the welding zones between T35 and TA6V, cavities are observed. These cavities seem caused by the vaporization of the aluminum, present in the TA6V, during the welding operation. The mechanical behavior of T35 titanium is described using monotonic tensile tests, tensile/recovery tests and monotonic and cyclic shear tests. These tests have shown an anisotropic elastic-viscoplastic behavior with an negative isotropic hardening. The modeling of the mechanical behavior and the identification of related parameters use the experimental database obtained previously. It is shown that an anisotropic model with isotropic and kinematic hardening accurately describe the stress and strain anisotropy, the cyclic shear behavior and the plastic behavior for strain levels up to 50%. Finally, the failure of T35 titanium sheets is studied. A stable propagation with a high plastic deformation at the crack tip is found. Various tomography and laminography observations revealed the presence of few cavities near cracks, which indicates that there is few damage during the crack propagation.

Noise in a fluid system can be treated with a prototypical liner-style suppressor, an expansion chamber which includes an internal annulus of syntactic foam. A syntactic foam liner consists of host material with hollow microspheres which collapse under pressure to add compliance to the suppressor. The liner effectively increases the transmission loss of the suppressor, or ratio between inlet and outlet acoustic energy. Currently, liner-style suppressors are not commercially available. This study investigates the integration of solid liner material within suppressor shells while also analyzing the effect of flow-smoothing diffusors on the transmission loss of the suppressor. The diffusors function to center the liner within the device, while reducing the potential for turbulence-induced self-noise. The diffusor may also impact the longevity of the liner, by reducing mechanical erosion. The results of the study provide additional insight to the commercial viability of the liner-style suppressor.

The theme of the Master's Thesis is liner shipping. The main issue concerns the changes in the liner shipping market caused by the economic crisis started in 2008. The first theoretical part of the thesis deals with characterization and classification of the liner shipping. Further the thesis concentrates on the containerization and the international organizations in maritime business. The second part of the thesis considers the development of the liner shipping market since 2008 till present days. The fundamental part aims to the measures taken by liner operators and freight forwarders.

Resumo: O presente estudo teve como objetivo avaliar o efeito citotóxico dos monômeros isobutil metacrilato (IBMA) e 1,6 - Hexanediol dimetacrilato (1,6 - HDMA), do plastificante di-n-butil ftalato (DBP), e dos produtos de degradação ácido metacrílico (AM) e ácido benzóico (AB) sobre células L929. Esses compostos foram testados em faixas de concentrações liberadas, em um período de 30 dias, por materiais reembasadores rígidos, previamente quantificadas em estudos anteriores. O efeito citotóxico foi verificado por meio dos testes de MTT e 3H-timidina, após as células terem sido expostas às substâncias testadas nas concentrações estabelecidas. A classificação da citotoxicidade foi baseada na viabilidade celular em relação ao controle (células expostas ao meio sem as substâncias testadas). A atividade de síntese de DNA foi inibida por todos os compostos. Os resultados do presente estudo demonstraram que o teste de 3H-timidina foi mais sensível que o teste de MTT e que os compostos avaliados mostraram diferentes níveis de citotoxicidade in vitro. A atividade da desidrogenase mitocondrial diminuiu nas células tratadas com os monômeros, o plastificante e o produto de degradação AM; porém, para o AB, a maioria das concentrações testadas não apresentou efeito citotóxico. / Abstract: The aim of this study was to evaluate the cytotoxic effect of the monomers 1,6 - hexanediol dimethacrylate (1,6 - HDMA) and isobutyl methacrylate (IBMA), the plasticizer di-n-butyl phthalate (DBP), and the degradation by-products methacrylic acid (MA) and benzoic acid (BA) on L929 cells. These compounds were tested in the range of concentrations released in 30 days from hard chairside reline resins that were quantified in previous investigations. Cytotoxic effects were assessed by using MTT and 3H - thymidine assays after the cells had been exposed to the test compounds at the given concentrations. Cytotoxicity was rated based on cell viability relative to controls (cells exposed to medium without test substances). The results presented in this study demonstrated that the 3H-thymidine assay was more sensitive than the MTT assay, and all compounds tested showed varying degrees of cytotoxic effect in vitro. DNA synthesis activity was inhibited by all compounds. Mitochondrial dehydrogenase activity decreased in cells treated with monomers, plasticizer and MA by-product, whereas no cytotoxic effect was observed on contact with BA at the majority of concentrations tested. / Orientador: Ana Lucia Machado / Coorientador: Iracilda Zeppone Carlos / Banca: Ana Cláudia Pavarina / Banca: Cláudia Lovato da Silva / Mestre