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Effects of soluble soybean polysaccharide as filling agent on the properties of leathersTang, Zhenye, Zhong, Jide, Feng, Xianqing, Zhang, Yafei, Hu, Yadi, Liu, Hui, Liu, Jie, Ferah, Cem Emre, Tang, Keyong 28 June 2019 (has links)
Content:
Soluble soybean polysaccharide (SSPS) is good in emulsification, and stable emulsion may be formed with the addition of SSPS in fatliquoring agents. In this paper, with wet blues as raw materials, after
being retanned and neutralized, fatliquoring and filling up with SSPS were carried out at the same time, with different amounts of SSPS, i.e., 1%, 3%, 5%,7% in weight. The leather samples were dried at room temperature. The effects of SSPS amounts on the thickness, air permeability and water vapor permeability of the crust leather were studied. The tensile properties of the leathers filled by SSPS were analyzed. The results indicated that with increasing the amounts of SSPS, the thickness and the water vapor permeability of the leathers increase, while the air permeability decreases slightly. The maximum stress-strain capacity of leathers decreases with increasing the SSPS amount. At the SSPS amount of 3%, the leather is good in softness, as well as in physical and mechanical properties.
Take-Away:
1.SSPS from soybean dregs is an acidic polysaccharide, which is rich in raw materials and low in cost.
2.Leathers filled with SSPS have good performance.
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[en] EVALUATION OF THE FIELD LATERAL STRESS OF OVERCONSOLIDATED CLAYS: LABORATORYTESTS IN A SOIL FROM THE GUABIROTUBA FORMATION / [es] EVALUACIÓN DE TENSIÓN LATERAL DEL CAMPO DE ARCILLAS SOBREADENSADAS ENSAYOS DE LABORATORIO CON UN SUELO DE LA FORMACIÓN GUABIROTUBA / [pt] AVALIAÇÃO DA TENSÃO LATERAL DE CAMPO DE ARGILAS SOBREADENSADAS: ENSAIOS DE LABORATÓRIO COM UM SOLO DA FORMAÇÃO GUABIROTUBAROBERTA BOMFIM BOSZCZOWSKI 27 September 2001 (has links)
[pt] A maioria dos métodos de laboratório disponível para a
avaliação das tensões horizontais in situ é aplicável
somente a solos normalmente adensados ou levemente
sobreadensados. A avaliação do estado de tensões efetivas
in situ de solos rijos sobreadensados e, conseqüentemente o
desempenho tensão-deformação desses solos, envolve um
considerável grau de incertezas devido à dificuldade na
determinação da tensão lateral de campo. Apresenta-se,
neste trabalho, resultados de um estudo experimental de
laboratório que teve por objetivo: obter informações de
compressibilidade do material e do comportamento tensão-
deformação em condições não drenadas, e avaliar a tensão
lateral efetiva in situ de um solo da Formação Guabirotuba,
que se situa na Bacia Sedimentar de Curitiba.
Propõe-se uma nova metodologia experimental para a
determinação da tensão lateral de campo, tendo em vista que
as metodologias apresentadas na literatura não são
adequadas para solos rijos e sobreadensados. Na primeira
fase deste estudo foram realizados ensaios de
caracterização completa, análise mineralógica e de
microscopia eletrônica. Após a caracterização física do
material, passou-se ao estudo do comportamento
tensãodeformação e resistência com a execução de ensaios
triaxiais e edométricos. Foram executados ensaios triaxiais
não drenados com corpos de prova adensados isotropicamente,
e ensaios de adensamento com velocidade constante de
deformação de um solo intacto da Formação Guabirotuba e de
um solo da mesma Formação, porém laterizado. O método
proposto para a avaliação da tensão lateral de campo está
baseado no conceito de superfícies de escoamento, ou seja,
a história de tensões de um solo está relacionada com seu
comportamento tensão-deformação-rigidez, e, portanto,
pode ser determinado através desta. Foram executados
ensaios triaxiais com trajetória de tensões controlada, de
acordo com a metodologia proposta, em amostras indeformadas
desta Formação. / [en] Most of the available laboratory methods for the evaluation
of the in situ horizontal stresses are usually applicable
only to normally consolidated or slightly overconsolidated
soils. The assessment of the in situ effective stresses
state of rigid, overconsolidated soils, and consequently of
their stress-strain performance , involves a considerable
degree of uncertainty due to the difficulty in the
determination of the field lateral stresses . This thesis
presents the results of an experimental study performed in
the laboratory to gather information on compressibility and
undrained stress-strain characteristics, and to determine
the in situ effective lateral stress of a soil from the
Guabirotuba Formation, at the Curitiba Sedimentary Basin,
in the South of Brasil. The first stage of the study
comprised characterization tests, mineralogical analysis
and electronic microscopy evaluations. After the physical
characterization of the material, it was carried out the
study on the stress-strain-strength behaviour through
undrained triaxial tests and oedometric tests with constant
rate of deformation. Unweathred and latherized soil samples
from the Guabirotuba formation were used in such
investigations. As the methodologies presented in the
literature are not appropriate for rigid, overconsolidated
soils, a new experimental technique for the determination
of the in situ lateral stress was proposed. The proposed
method is based on the concept of yield surfaces. The
stress history of a soil is related to its stress-strain
behaviour and, therefore, can be inferred through monitoring
changes of the soil rigidity under a given stress path.
Following the proposed methodology, stress-path controlled
triaxial tests with internal measurement of axial strains
were performed in undisturbed samples of the Guabirotuba
Formation, providing an assessment of the field lateral
stress of the material. / [es] La mayoría de los métodos de laboratorio disponibles para la evaluación de las tensiones
horizontales in situ puede ser aplicado solamente a suelos normalmente adensados o levemente
sobreadensados. La evaluación del estado de tensiones efectivas in situ de suelos duros
sobreadensados y, consecuentemente el desempeño tensión deformación de esos suelos, involucra
un considerable grado de incertezas debido a la dificuldad en la determinación de la tensión lateral
de campo. En este trabajo se presentan resultados de un estudio experimental de laboratorio
realizado con el objetivo de obtener informaciones de compresibilidad del material y del
comportamiento tensión deformación en condiciones no
drenadas, y evaluar la tensión lateral efectiva in situ de un suelo de la Formación Guabirotuba,
situada en la Bacia Sedimentar de Curitiba. Se propone una nueva metodología experimental para
la determinación de la tensión lateral de campo, considerando que las metodologias presentadas en
la literatura no son adequadas para suelos duros y sobreadensados. En la primera fase de este estudio
fueron realizados ensayos de caracterización completa, análisis mineralógica y de microscopia
electrónica. Después la caracterización física del material, se pasó al estudio del comportamiento
tensión-deformación y resistencia con la ejecución de ensayos triaxiales y edométricos. Fueron
ejecutados ensayos triaxiales no drenados con cuerpos de prueba adensados isotrópicamente, y
ensayos de adensamento con velocidad constante de deformación de un suelo intacto de la
Formación Guabirotuba y de un suelo de la misma Formación, pero laterizado. El método propuesto
para la evaluación de la tensión lateral de campo está basado en el concepto de superfícies de
vaciado, o sea, la historía de tensiones de un suelo está relacionada con su comportamiento
tensión-deformación-rígidez, y, por tanto, puede ser determinado a través de ésta. Fueron ejecutados
ensayos triaxiales con trayectoria de tensiones controlada, de acuerdo con la metodología propuesta,
en muestras indeformadas de esta Formación.
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Molecular Simulation of Anisotropic Stress and Structure in polymersSrivastava, Prashant Kumar January 2014 (has links) (PDF)
This dissertation presents a numerical study using molecular dynamic simulations
that interrogates the polymer structure as it is strained continuously in time and correlates it with the stress developed in it. We investigate the role of external control variables such as temperature, strain-rate, chain length, and density. At temperatures higher than glass transition, stress anisotropy is reduced even though bond stretch is greater at higher temperatures. There is a significant increase in stress level with increasing density. At faster rates of loading stress anisotropy increases. Deformation is mostly due to bond stretch and bond bending rather than overall shape and size. Stress levels increase with longer chain length. Cross-linkers beyond a critical value of functionality cause increased constraint on the motion of monomers and uniaxial stress developed increases. Stacking of
chains also plays a dominant role in terms of excluded volume interactions. Low density, high temperature, low values of functionality of cross-linkers, and short chain length, facilitate chain uncoiling and chain slipping in crosslinked polymers. Uniaxial stress in linear polymers, on the other hand, is only mildly in uenced by temperature. Sinusoidal strain loading clearly reveals the viscoelastic nature of polymers. Internal structural parameters of
the chains such as bond length, bond angle show hysteresis during loading and unloading. However, parameters representing overall size and shape of chains do not display any hysteresis. Small size magnetic particles and their small volume fractions in polymers show no signi cant e ect of applied external magnetic eld on anisotropic stress. Stress increases with lowering temperature, increasing density, decreasing volume fraction of magnetic particles, and increasing chain length
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Nano-Scale Investigation of Mechanical Characteristics of Main Phases of Hydrated Cement PasteHajilar, Shahin 18 March 2015 (has links)
Hydrated cement paste (HCP), which is present in various cement-based materials, includes a number of constituents with distinct nano-structures. The elastic properties of the HCP crystals are calculated using molecular dynamics (MD) methods. The accuracy of estimated values is verified by comparing them with the results from experimental tests and other atomistic simulation methods. The outcome of MD simulations is then extended to predict the elastic properties of the C-S-H gel by rescaling the values calculated for the individual crystals. To take into account the contribution of porosity, a detailed microporomechanics study is conducted on low- and high-density types of C-S-H. The obtained results are verified by comparing the rescaled values with the predictions from nanoindentation tests. Moreover, the mechanical behavior of the HCP crystals is examined under uniaxial tensile strains. From the stress-strain curves obtained in the three orthogonal directions, elastic and plastic responses of the HCP crystals are investigated. A comprehensive chemical bond and structural damage analysis is also performed to characterize the failure mechanisms of the HCP crystals under high tensile strains. The outcome of this study provides detailed information about the nonlinear behavior, plastic deformation, and structural failure of the HCP phases and similar atomic structures.
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Estudo experimental do comportamento tensão-deformação de uma argila adensada unidirecionalmente / A experimental study of the stress-strain behavior of a one-dimensionally consolidated clayStancati, Gene 05 February 1991 (has links)
O trabalho é um estudo experimental do comportamento tensão-deformação, em argila adensada unidirecionalmente, após mistura com água. Para sua execução, foram desenvolvidos equipamentos para adensamento de grandes quantidades de Lama, e medidores eletrônicos específicos para deformações volumétricas e radiais, usados em ensaios de compressão triaxial. O modelo da teoria clássica elasto-linear, para solos com comportamento anisotrópico é utilizado, após desenvolvimento algébrico, na obtenção dos parâmetros da argila. Nos cálculos, são aplicados processos estatísticos de regressões polinomiais. São analisadas as correlações dos parâmetros elásticos iso e anisotrópicos (Módulos de Elasticidade, Coeficientes de Poisson e Módulos de Elasticidade Transversal), com as tensões confinantes dos ensaios triaxiais, e com os Índices de pré-adensamento OCR das Lamas. / This work is an experimental study of the stress-strain behavior on clay one-dimensionally consolidated, after mixing with water. A consolidation equipment designed for great mass of mud and specific electronic apparatus for volumetric and lateral displacements on the triaxial tests were developed for this study. The classical theory of elasto-linear model for anysotropic soils is used, after algebraic manipulation, to obtain clay parameters. Multiple regressions are used for variables computations. Iso and anysotropic elastic parameters (Young modulus, Poisson ratio and shear modulus) are correlated with the confinant stresses and the over-consolidation-ratios (OCR).
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Estudo do comportamento mec?nico de areias artificialmente cimentadas / Evaluation of the mechanical behaviour of artificially cemented sandLopes, Francisco Mateus Gomes 09 March 2012 (has links)
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Previous issue date: 2012-03-09 / Soil improved with the addition of cement have been utilized as an alternative to the
construction of various types of geotechnical works, almost always present economic
and environmental advantages. This paper presents a study on the usage of cement
in the improvement of mechanical properties of sandy soils, characteristic of the
region of Natal, collected from its dunes. This research was made in order to analyze
the influence of cement content, voids, and also including water immersion
and confining pressure. Samples molded from cement-soil mixtures were tested for
unconfined compression tests and triaxial tests. The samples had the percentage of
cement mixed in 2.5%, 5% and 10% by weight. The cement agent used was the
Portland Cement of High Early strength(CPV-ARI), which promoted agility to the
experimental procedure for presenting a rapid gain in strenght. The void ratio used
ranged from 0.7 (more compact), 0,9 and 1,1(softer). The soil under study can be
considered as pure sand. In general, it can be stated that the larger the amount of
cement added to the sand studied is, the greater ultimate strength will be. Likewise,
as more compact the soil is, the less void ratio and more resistant it will be present.
The confining pressure tends to increase the resistance of the specimens. The
cementing adopted grades showed that the use of different criteria for failure did not
significantly alter the stress-strain parameters for the sand studied. The angle of
friction values were found within the typical range of medium and compact sands.
Cementing acted in the sand providing an intercepted cohesion which increased
enhancing the potential cementation. In triaxial compression tests, the sand with void
ratio is equal to 0.7 and showed the expected behavior for a compact sand while the
stress-strain behavior of the same sand with the void ratio of 0.9 tended to be
expected for the soft sand as well / Solos melhorados com adi??o de cimento t?m sido bastante utilizados como
alternativa na constru??o de diversos tipos de obras geot?cnicas, quase sempre por
apresentar vantagens econ?micas e ambientais. Este trabalho apresenta um estudo
sobre a utiliza??o de cimento no melhoramento das propriedades mec?nicas de
solos arenosos caracter?sticos da regi?o de Natal, coletados em dunas. Foi avaliada
a influ?ncia do teor de cimento, do ?ndice de vazios, da inunda??o e da tens?o
confinante. Corpos-de-prova moldados a partir de misturas de solo-cimento foram
submetidos a ensaios de resist?ncia ? compress?o simples e ? compress?o triaxial
convencional. Nas amostras as porcentagens de cimento foram variadas em 2,5%,
5% e 10% em peso. O agente cimentante utilizado foi o Cimento Portland de Alta
resist?ncia inicial (CP-V ARI), que promoveu agilidade ao procedimento experimental
por apresentar um processo de cura mais r?pido.Os ?ndices de vazios utilizados
variaram de 0,7 (mais compacto), 0,9 e 1,1(mais fofo). O solo estudado pode ser
considerado como uma areia pura. De uma forma geral, pode-se afirmar que quanto
maior a quantidade de cimento adicionado ? areia estudada, maior a sua resist?ncia
final. Da mesma forma, quanto mais compacto estiver esse solo, isto ?, quanto
menor o ?ndice de vazios, mais resistente ele se apresentar?. A tens?o confinante
tende a aumentar a resist?ncia dos corpos de prova. Nos graus de cimenta??o
adotados, a utiliza??o de diferentes crit?rios de ruptura n?o alterou
significativamente os par?metros tens?o-deforma??o para a areia estudada. Os
valores de ?ngulo de atrito encontrados estavam dentro dos valores t?picos para
areias m?dias e compactas. A cimenta??o agiu na areia de modo a proporcionar um
intercepto de coes?o que aumentou com o incremento da cimenta??o. Nos ensaios
de compress?o triaxial, a areia com ?ndice de vazios igual a 0,7 apresentou o
comportamento esperado para uma areia compacta, enquanto o comportamento
tens?o deforma??o da mesma areia com ?ndice de vazios de 0,9 tendeu ao
esperado para a areia fofa
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Estudo experimental do comportamento tensão-deformação de uma argila adensada unidirecionalmente / A experimental study of the stress-strain behavior of a one-dimensionally consolidated clayGene Stancati 05 February 1991 (has links)
O trabalho é um estudo experimental do comportamento tensão-deformação, em argila adensada unidirecionalmente, após mistura com água. Para sua execução, foram desenvolvidos equipamentos para adensamento de grandes quantidades de Lama, e medidores eletrônicos específicos para deformações volumétricas e radiais, usados em ensaios de compressão triaxial. O modelo da teoria clássica elasto-linear, para solos com comportamento anisotrópico é utilizado, após desenvolvimento algébrico, na obtenção dos parâmetros da argila. Nos cálculos, são aplicados processos estatísticos de regressões polinomiais. São analisadas as correlações dos parâmetros elásticos iso e anisotrópicos (Módulos de Elasticidade, Coeficientes de Poisson e Módulos de Elasticidade Transversal), com as tensões confinantes dos ensaios triaxiais, e com os Índices de pré-adensamento OCR das Lamas. / This work is an experimental study of the stress-strain behavior on clay one-dimensionally consolidated, after mixing with water. A consolidation equipment designed for great mass of mud and specific electronic apparatus for volumetric and lateral displacements on the triaxial tests were developed for this study. The classical theory of elasto-linear model for anysotropic soils is used, after algebraic manipulation, to obtain clay parameters. Multiple regressions are used for variables computations. Iso and anysotropic elastic parameters (Young modulus, Poisson ratio and shear modulus) are correlated with the confinant stresses and the over-consolidation-ratios (OCR).
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UPSCALING OF A THERMAL EVOLUTION EXPERIMENT ON SHREDDED-TIRE MONOFILLSGelaye, Ababu A. January 2017 (has links)
No description available.
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[pt] COMPORTAMENTO GEOTÉCNICO DA BARRAGEM DE CURUÁ-UNA, PARÁ / [en] GEOTECHNICAL BEHAVIOR OF CURUÁ-UNA DAM, PARÁ.LARYSSA PETRY LIGOCKI 03 October 2003 (has links)
[pt] O comportamento geotécnico da barragem de Curuá-Una, Pará,
foi estudado devido à importância que a barragem representa
para a Região Norte do Brasil. A usina hidrelétrica de
Curuá-Una, inaugurada em 1977, está localizada na
Amazônia, próxima à cidade de Santarém. O estudo englobou a
avaliação das condições atuais de operação e a previsão de
desempenho após uma possível elevação de 1,5m do nível do
reservatório, com e sem alteamento simultâneo da crista da
barragem. A elevação do nível do reservatório
possibilitaria o aumento da potência útil da usina,
beneficiando toda a região. Uma ampla campanha de
ensaios geotécnicos foi realizada em amostras indeformadas
dos materiais constituintes da barragem. As amostras de
bloco foram extraídas dos taludes de jusante e montante,
acima do nível freático. O programa experimental incluiu
ensaios de caracterização, permeabilidade, adensamento,
cisalhamento direto, e triaxiais, com diferentes condições
de umidade. A pesquisa envolveu também a análise dos
resultados da instrumentação de campo, composta por
piezômetros instalados no corpo da barragem e na fundação
de material arenoso. Uma surgência da linha freática foi
identificada no talude de jusante, sugerindo um
funcionamento inadequado do filtro vertical. As análises
englobaram simulações numéricas da elevação do nível do
reservatório e da cota da crista da barragem, com o
objetivo de avaliar a deformabilidade do maciço. Foram
também definidos os níveis de alerta referentes à segurança
da barragem, com base em estudos de estabilidade realizados
para diferentes condições de geometria e carregamento. / [en] The geotechnical behavior of Curuá-Una dam, Pará, was
studied due its importance to the North Region of Brazil.
The power plant, in operation since 1977, is located in the
Amazon forest, next to the city of Santarém. The study was
comprised of the evaluation of current operation conditions
of the dam and prediction of its performance after a
possible rise of 1,5m of the level of the reservoir with
and without simultaneous rise of the dam s crest. The rise
of the reservoir would increase the power capacity of Curuá-
Una plant, benefiting the entire region. A comprehensive
program of geotechnical tests was carried out on
undisturbed samples of the dam materials. Block samples
were extracted from the upstream and downstream slopes of
the dam. The experimental program included characterization
tests, permeability, consolidation, direct shear and
triaxial tests, with different saturation conditions. The
research also included the analysis of field
instrumentation results. The instrumentation included
several piezometers, installed in the body of the dam and
in the sandy foundation. A surgency of the freatic line was
identified at the downstream slope, suggesting a
malfunctioning of the vertical filter. The analyses
included numerical simulations of different reservoir and
crest levels, with objective to evaluate the deformability
of the earth embankment. In addition, stability studies for
different geometries and loading conditions were also
carried out. Alert levels regarding the dam s stability were
established.
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Étude expérimentale du comportement hydro-mécanique de la terre crue compactée pour la construction / Experimental study of the hydro-mechanical behaviour of compacted earthen material for constructionChampiré, Florian 19 September 2017 (has links)
Le matériau terre peut apporter une réponse face aux problèmes que les constructions modernes rencontrent en termes d’enjeux sociétaux, économiques et écologiques. Cependant, les difficultés à comprendre et à prédire son comportement représente un obstacle au développement de cette technique dans les pays développés. Cette thèse s’insère dans un projet de recherche appelé « Primaterre » et financé par l’Agence Nationale de la Recherche française (ANR). Il vise à apporter les connaissances scientifiques nécessaires afin de pallier ce manque et aider à établir des règlementations adaptées. Ce travail s’intéresse plus particulièrement à l’impact de l’eau sur le comportement mécanique de la matrice fine du matériau, qui a un impact essentiel sur le comportement du matériau dans son ensemble. Cette matrice est constituée de sables, de limons, et d’argiles, et ce sur trois types de terres prélevées sur d’anciennes constructions en pisé. Afin de réaliser des échantillons les plus identiques et homogènes possible, un moule a tout d’abord été conçu, ce qui a permis de travailler avec des échantillons cylindriques de 3,5cm de diamètre et 7cm de hauteur. Une cellule triaxiale a été utilisée et, la seconde étape a été de concevoir les dispositifs permettant la mesure des déformations axiales et radiales, le conditionnement à température contrôlée et l’imposition d’un flux d’air humide variable de part et d’autre de l’échantillon. Différents types d’essais ont alors pu être réalisés : des essais triaxiaux à différent taux d’humidité relative ainsi que des essais de gonflement. Les paramètres mécaniques obtenus ont pu être analysés à la lumière des caractéristiques matériaux mesurées en parallèle. Enfin, l’analyse des essais de gonflement a été menée à bien à l’aide d’un modèle numérique, et ce afin de pouvoir évaluer des paramètres caractéristiques plus complexes. Ce travail de thèse se conclut par une étude supplémentaire, visant à évaluer l’impact du changement de taille d’échantillon sur les paramètres mécaniques mesurés précédemment. Ces essais ont été effectués sur des échantillons approximativement deux fois plus grands, et grâce à un dispositif expérimental plus simple, utilisant la mesure par corrélation d’images. / Earthen buildings can provide an answer to face difficulties in modern constructions in both terms of sociology, economics as well as ecology. However, the difficulty to understand and to predict their behavior prevent the spreading of this technique in developed countries. This PhD is part of a research program called “Primaterre” and founded by the French National Agency for Research. It aims at providing the necessary scientific knowledge to overcome this lack and at helping the creation of appropriate standards. This work is more precisely focusing on the impact of water on the mechanical behavior of the fine proportion of the material, including sand, silt and clay, and on three different earths coming from existing rammed earth constructions. In order to be able to produce samples as identical and homogeneous as possible, a mold has first been designed, which enable to manufacture cylindrical samples with diameter of 3.5cm and height of 7cm. A triaxial cell was used and, the second step was to design different devices allowing the measurement of axial and radial deformations, the conditioning at constant temperature, and the command of a variable moist air flux at both sides of the sample. Different types of tests have thus been realized : triaxial tests at different relative humidity, as well as swelling tests. The mechanical parameters thus obtained have been analyzed in comparison with material characteristics measured in parallel. Finally, results of swelling tests have been analysed using numerical modelling, in order to assess more complex material characteristics. This thesis work ends with an additional study, aiming at evaluating the impact of scale change on the mechanical parameters previously measured. Tests have been conducted on sample approximatively twice larger, and thanks to a simpler experimental device using measurement through image correlation.
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