In diesem Beitrag werden ein Berechnungsverfahren und ein Bemessungskonzept für biegebeanspruchte textilbetonverstärkte Stahlbetonbauteile vorgestellt. Ihre Anwendbarkeit wird durch die Auswertung von Versuchen an verstärkten Stahlbetonplatten mit einer Reihe veränderlicher Ausgangswerte überprüft. Als Ergebnis dieser Arbeit stehen dem Anwender einfach nutzbare, praxisgerechte Bemessungstabellen zur Verfügung. In dieser Version weisen die Grafiken eine bessere Qualität auf. / This article introduces a calculation method and a design concept for reinforced concrete elements strengthened with textile concrete. Its applicability is verified by an analysis of tests with strengthened steel reinforced concrete slabs with a certain variety of design parameters. Results of this work are easy manageable, praxis-orientated design tables that are available for users. This version contains figures with a better quality.

Low temperature cracking is an important form of asphalt pavement deterioration in cold regions. The cracks develop when thermally induced stresses exceed the fracture resistance of the asphalt pavement. In this study, by incorporating HMA fracture mechanics into thermal cracking model, a new integrated model is introduced to investigate low temperature cracking performance. To evaluate its reliability and accuracy, the predicted thermally induced stress and failure temperature are compared with the fracture stress and fracture temperature obtained from thermal stress restrained specimen test. The findings indicate that this HMA fracture mechanics-based thermal cracking model has a great potential to reliably evaluate the performance of asphalt mixtures subjected to thermally induced damage.

The issue of ductile damage prediction can be generally divided in two types of tasks. The first one is to preventing the initiation of ductile damage with is most common group of calculation today. The second task can be described as aimed damaging, such as machining, cutting, etc. The significant development of this issue occurred in recent decades by help of development and access to powerful computational techniques and new experimental possibilities. However, the behaviour of ductile damage at multiaxial proportional and non-proportional loading is insufficiently described. This thesis helped to clarify some of the unknown this topic. It contributed to the understanding of selected materials behaviour at room temperature and quasistatic loading. Austenitic stainless steel AISI 316L was selected for detail study of ductile damage. A large number of experiments were performed on this material, such as uniaxial tensile tests of smooth and notched specimens, upsetting tests of smooth cylinder and special cylinder with dimple, butterfly specimens, notched tube specimens and penetration tests. Experimental results is used for calibration of five so-called simple criteria, taking into account fracture strain and stress triaxiality (Equivalent fracture strain, Johnson-Cook, simplify Bao-Wierzbicki, RT, RTCL) and universal criteria (Bai-Wierzbicki, Xue-Wierzbicki, EMC, LOU, KHPS). SPT potentially enable the determination of actual mechanical behaviour using only a fraction of specimen volume compared to standard specimen. It is promising tool to improve accuracy when assessing working life of components in operation. The inverse numerical simulation loop of SPT was designed using program OptiSLang on the basis of detailed sensitivity analysis. It was achieved 2% deviation of yield strength and 6% deviation of ultimate strength obtained from tensile tests. A several modification of SPT specimen was suggested for universal criteria calibration of small material volume. The 3D numerical model was built for numerical simulation with ductile damage simulation. The criteria KHPS and EMC gave the most accurate results.

No description available.

No description available.

Walt Whitman used animistic techniques in his poetry and prose, specifically "Song of the Redwood Tree," "Out of the Cradle Endlessly Rocking," and Specimen Days. The term animism can be traced to the Latin root of the word, anime, which connotes a "soul" or "vitality." So, when one is talking about animistic techniques, one is speaking of the (metaphoric or realistic) ensoulment of natural objects. In the wake of a growing global crisis modern scholarship has begun reexamining the implications of this belief; often it introduces ambiguities into an otherwise comfortable relationship of unquestioned human domination. In Specimen Days, Whitman seems to have a more clear view of his natural philosophy, in which he expresses his belief that nature possesses an inherency that he envies and an ability to communicate that quality with him. However, Whitman's "Song of the Redwood Tree" is ambiguous and contradicting. Whitman creates a vision of Manifest Destiny by portraying settlers in California clearing space for houses and agriculture by cutting down the majestic redwood forests. However, this poem contains a particularly odd element: the trees have a voice. They mourn their own demise while simultaneously celebrating the arrival of the new American populace. It is a conflicting image. The animistic, majestic qualities of the trees challenge an anthropocentric view of the world, not allowing the reader to quickly disregard the extinction of the redwood forests in order to embrace American ideals of progress, which in a way defeats the more imperialistic message of the poem. Another comparison, with "Out of the Cradle Endlessly Rocking," demonstrates how important subversion of self to place is when using animistic techniques in poetry. This poem implies that animate nature is a locus for Whitman's creative genius, both inspiring his poetry and permeating it with confusion. Whitman's very engagement with the process of imagining a voice for nature inserts doubt into some of his more imperialistic pronouncements and encourages the reader to question his own previously unexamined assumptions. Animistic literary techniques have the potential to encourage an involvement with non-human nature, along with a more conscious awareness of the way we use (and abuse) that Other.

Este trabalho aborda uma investigação numérica-experimental sobre o comportamento à fratura por clivagem de um aço de alta resistência e baixa liga ASTM A572 Grau 50 usando corpos de prova SE(B) em configurações padronizadas e não padronizadas, incluindo a configuração PCVN não padronizada. O principal objetivo desse estudo é contribuir para o desenvolvimento de um procedimento de ensaio de tenacidade à fratura aplicável a geometrias SE(B) com distância entre apoios variável (S/W) e carregada sob configuração de flexão por 3 e 4 pontos. O objetivo secundário, mas não menos importante, é investigar os efeitos da geometria e do modo de carregamento sobre as distribuições dos dados de tenacidade à fratura medidas experimentalmente e suas implicações na caracterização da dependência da tenacidade em relação à temperatura baseada na metodologia da curva mestra. Com base nesses propósitos, é fornecido um novo e extenso conjunto de fatores plásticos eta (?p) aplicáveis às geometrias SE(B) não padronizadas para estimar os valores de tenacidade à fratura, incluindo a integral J e o parâmetro CTOD, medidos experimentalmente em termos de registros de carga e deslocamento. A fim de facilitar o contato com os demais protocolos de ensaios, é também fornecido um novo conjunto de fatores rotacionais plástico (rp) para determinar o CTOD baseado no modelo da rótula plástica. Os ensaios de tenacidade à fratura, realizados em diversas geometrias SE(B) com distância entre apoios variável (S/W) extraídas na direção transversal (T-L) de uma chapa de aço ASTM A572 Grau 50, fornecem os dados de tenacidade à fratura por clivagem em termos da integral-J medida no ponto de instabilidade, Jc. Os resultados experimentais mostram um potencial efeito da geometria do corpo de prova e do modo de carregamento sobre os valores de Jc, os quais podem ajudar a mitigar os efeitos da perda de restrição plástica frequentemente observada em corpos de prova de pequenas dimensões. A aplicação exploratória para determinar a temperatura de referência, T0, a partir da metodologia da curva mestra também fornece um suporte adicional para o uso de corpos de prova SE(B) não padronizados como uma alternativa geométrica nos procedimentos rotineiros de avaliação de tenacidade à fratura, incluindo o uso de corpos de prova de pequenas dimensões nas medições de tenacidade quando a disponibilidade limitada de material e a capacidade de carregamento da máquina são as principais preocupações. / This work addresses a numerical-experimental investigation on the cleavage fracture behavior of an ASTM A572 Grade 50 high strength, low alloy structural steel using standard and non-standard SE(B) specimens, including a non-standard PCVN configuration. The main purpose of this study is to contribute to the development of a fracture toughness test procedure applicable to bend geometries with varying specimen span over width ratio (S/W) and loaded under 3-point and 4-point flexural configuration. The secondary purpose, but none the less important, is to investigate the effects of geometry and loading mode on experimentally measured fracture toughness data distributions and implications for the characterization of the temperature dependence of toughness based on the Master Curve methodology. Based on these purposes, a large new set of plastic ?-factors applicable to these non-standard bend geometries which serve to estimate the experimentally measured toughness values in terms of load-displacement records, including the J-integral and the crack tip opening displacement (CTOD), is provided. In order to facilitate contact with other test protocols, a new set of rotational factors, rp, to determine the CTOD based on the plastic hinge model is also described. Fracture toughness testing conducted on various bend geometries with varying specimen span (S/W) extracted in the T-L orientation from an A572 Grade 50 steel plate provides the cleavage fracture resistance data in terms of the J-integral at cleavage instability, Jc. The experimental results show a potential effect of specimen geometry and loading mode on Jc-values which can help mitigating the effects of constraint loss often observed in smaller fracture specimens. An exploratory application to determine the reference temperature, T0, derived from the Master Curve methodology also provides additional support for using non-standard bend specimens as an alternative specimen geometry in routine fracture assessments, including the use of small-scale fracture specimens to measure fracture toughness properties when limited material availability and test machine capacity are of major concern are of major concern.

Für die Materialcharakterisierung und Parameteridentifikation von technischen Elastomeren werden homogene Probekörper benötigt. Eine besonders wichtige Beanspruchungsart ist dabei der einachsige Zug/Druck. Für Versuche dieser Art findet die Standard-Hantel Anwendung, die für kombinierte Zug-/Druckversuche geeignet ist. Allerdings lässt sich hier schon bei geringen Druckbelastungen ein inhomogener Messbereich detektieren. Ein Ziel dieser Arbeit besteht in der Entwicklung eines neuen und verbesserten Probekörpers, der für hochpräzise Zug-/Druckversuche geeignet ist. Im Gegensatz zur Standard-Hantel wird der für Messungen zugänglich gemachte homogene Messbereich deutlich verbessert. Darüber hinaus soll der Bereich der maximal erreichbaren Stauchung signifikant erhöht werden. Der Probekörper selbst weist dabei eine verhältnismäßig einfache Hantelgeometrie mit verlängertem Mittelteil auf. Durch ein spezielles Design der Halterungsgeometrie kann sowohl ein homogenes Verzerrungsfeld erreicht als auch eine hohe Knickstabilität gewährleistet werden. Die Grundidee besteht dabei darin, dass der Probekörper mit zunehmender Stauchung immer weiter mit der Halterungsgeometrie in Kontakt tritt und dadurch seine knickgefährdete Länge reduziert wird. Mit Hilfe eines speziellen Halterungsalgorithmus kann eine neue, verbesserte Halterungsgeometrie berechnet werden. Mit dem entwickelten Probekörper-Setup (bestehend aus Hantel- und Halterungsgeometrie) lassen sich dann eine Vielzahl phänomenologischer Eigenschaften von technischen Elastomeren wie Payne- Effekt, Mullins-Effekt, Erholungs- und Relaxationsverhalten vorzugsweise bei extremen Stauchungen (bis zu 70 %) untersuchen. Ein weiteres Ziel dieser Arbeit besteht in der Entwicklung eines Scherprobekörpers zur Realisierung präziser Schermessungen. Das Design soll dabei auf einem flächigen Probekörper (Elastomermatte) beruhen, um Alterungsuntersuchungen, Untersuchungen mit faserverstärkten Materialien und Versuche mit Vorreckungen realisieren zu können. Im Gegensatz zu herkömmlichen Scherprobekörpern soll dabei auf eine stoffschlüssige Verbindung mittels Kleben oder Anvulkanisieren aufgrund von Materialirritationen oder Schrumpf verzichtet werden. Im Rahmen dieser Arbeit wurde diesbezüglich ein spezielles Fixierdesign mit Stiften entwickelt, welches zur Ausbildung nahezu homogener Scherdeformationen führt. Damit lassen sich eine Vielzahl wichtiger Eigenschaften bei einer annähernd homogenen Scherdeformation untersuchen. / Homogeneous test specimens are required for material characterization and model parameter identification. An important kind of loading is uniaxial tension/compression. For this, a standard dumbbell is available for combined tension-compression tests. But even for small compressive strains the standard dumbbell leads to an inhomogeneous stress state in the measuring zone. One aim of this work is the development of a new test specimen, which is suitable for high-precision tension/compression tests. In comparison to the standard dumbbell the homogeneity in the measuring zone is significantly improved. Furthermore, the range of maximal compression is increased substantially. The test specimen itself consists of a slender dumbbell structure. By a special design of the mounting geometry, homogeneous stress and strain fields as well as a high stability can be achieved. For an increasing compression, the test specimen comes into contact with the mounting geometry and the critical length is reduced. By means of dynamic analysis, the mounting geometry was calculated and optimized. This method is a powerful tool for developing new mounting geometries, by taking into account both the stability and the homogeneity characteristic. With the developed specimen-setup (consisting of dumbbell and mounting geometry), the phenomenological characteristics of rubber like Payne effect, Mullins effect, recovery and relaxation behavior can be investigated up to a compressive strain of 70 %. Another aim of this work is the development of a shear specimen, which enables precision shear measurements for large shear values. The design is based on a planar test specimen (rubber mat) in order to enable ageing tests, tests with fibre-reinforced materials and tests with pre-stretching. In contrast to other shear specimens, a material-locking connection by gluing or vulcanizing sould be avoided in consequence of material irritation or shrinkage. For this, a special fixing design was developed, which enables a uniform initiation of shear deformation for different rubber thicknesses. Finally, the new shear specimen enables the investigation of typical rubber properties.

This thesis concerns the application of aberration corrected scanning transmission electron microscopy (STEM) to the quantitative analysis of industrial Pd-Pt core-shell catalyst nanoparticles. High angle annular dark field imaging (HAADF), an incoherent imaging mode, is used to determine particle size distribution and particle morphology of various particle designs with differing amounts of Pt coverage. The limitations to imaging, discrete tomography and spectral analysis imposed by the sample’s sensitivity to the beam are also explored. Since scattered intensity in HAADF is strongly dependent on both thickness and composition, determining the three dimensional structure of a particle and its bimetallic composition in each atomic column requires further analysis. A quantitative method was developed to interpret single images, obtained from commercially available microscopes, by analysis of the cross sections of HAADF scattering from individual atomic columns. This technique uses thorough detector calibrations and full dynamical simulations in order to allow comparison between experimentally measured cross section to simulated ones and is shown to be robust to many experimental parameters. Potential difficulties in its applications are discussed. The cross section approach is tested on model materials before applying it to the identification of column compositions of core-shell nanoparticles. Energy dispersive X-ray analysis is then used to provide compositional sensitivity. The potential sources of error are discussed and steps towards optimisation of experimental parameters presented. Finally, a combination of HAADF cross section analysis and EDX spectrum imaging is used to investigate the core-shell nanoparticles and the results are correlated to findings regarding structure and catalyst activity from other techniques. The results show that analysis by cross section combined with EDX spectrum mapping shows great promise in elucidating the atom-by-atom composition of individual columns in a core-shell nanoparticle. However, there is a clear need for further investigation to solve the thickness / composition dualism.

Made available in DSpace on 2017-07-21T20:42:39Z (GMT). No. of bitstreams: 1 Ederson Pauletti.pdf: 5739200 bytes, checksum: 362611be295a3342251b72d168512c61 (MD5) Previous issue date: 2013-03-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this work the ductile crack growth resistance curves (J-R curves) was evaluated for the steels used in the oil and gas pipelines from the X60 and X70 API 5L grades using the unloading compliance technique. The non standardized SE (T) specimens were used due to the same has low constraint, it is feature of pipelines. The plastic area for the obtaining the J integral was performed by measuring from the crack mouth open displacement, (CMOD). The central emphasis this research was evaluated the delamination phenomenon influence from the fracture toughness and along the J-R curve. As also the microtexture in close to delamination and ductile fracture regions, by using the Electron Backscatter Diffraction (EBSD) technique. The results have shown that value average of 355kJ/m2 was similar for both the shallow and deep crack specimens. The J-R curve values average from the shallow crack specimens have displayed most steep J-R curves, namely, it obtained higher energy values along the ductile crack propagation. Specimens that showed delaminations, during fracture process, obtained higher energy values along the ductile crack propagation. The occurrence of delaminations was more common in deep crack specimens. The microtexture results have shown a random grain sizes distribution. The components with higher intensity in the delamination region were α-fiber textures: {113} <110>, {112} <110>, {223} <110> the same cause anisotropy of mechanical properties and can be influenced out-of-plane constraint during the test. Moreover, there was the occurrence of the {100} <110> recrystallization texture component, which have deleterious effect in occurrence of delamination in microalloyed steels. Whereas in the ductile fracture region occurred the {111} <231>, {111} <132> and {111} <123> γ-fiber, which it can be influenced the ductile crack propagation process. / Neste trabalho foram investigadas as curvas de resistência ao crescimento de trinca dúctil para aços utilizados em tubulações de petróleo e gás, das classes API 5L X60 e X70, utilizando-se da técnica de variação da flexibilidade elástica. Espécimes SE(T) não padronizados foram utilizados, pois o mesmo possui baixa restrição ao fluxo plástico, característica de tubulações. A área plástica para obtenção da integral J foi obtida através da medida de deslocamento de abertura de trinca (crack mouth open displacement, CMOD). A ênfase central desta pesquisa foi avaliar a influência do fenômeno da delaminação na tenacidade à fratura (JIC) e na curva J-R em geral. Como também a obtenção da microtextura em regiões próximas à delaminação e fratura dúctil, que ocorrem durante o processo de fratura no ensaio de tenacidade à fratura, pelo uso da técnica de difração de elétrons retroespalhados (EBSD). Os resultados mostraram que o valor médio de tenacidade à fratura, de 355 kJ/m2 foi equivalente para espécimes com tamanho de trinca rasa e profunda. A média dos valores de curva J-R para espécimes com tamanho de trinca rasa mostrou curvas J-R mais íngremes, ou seja, obtiveram maiores valores energia ao longo da propagação dúctil de trinca. Os espécimes que apresentaram delaminações, durante o processo de fratura, obtiveram maior valor de energia ao longo do crescimento de trinca dúctil. A ocorrência das delaminações foi mais comum em espécimes com tamanho de trinca profunda. Os resultados de microtextura mostraram uma distribuição aleatória de tamanhos de grão. As componentes com maior intensidade na região próxima à delaminação foram as texturas de fibras α: {113}<110>, {112}<110>, {223}<110> que causam anisotropia das propriedades mecânicas e podem ter influenciado no estado triaxial de tensões durante o ensaio. Além disso, houve ocorrência da componente de textura de recristalização {100}<110>, a qual tem efeito deletério na ocorrência de delaminações em aços microligados. As componentes de fibra mais intensas na região próxima à fratura dúctil foram as texturas de fibra γ: {111}<231>, {111}<132> e {111}<123>, as quais podem influenciar no processo de propagação de trinca dúctil.