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Статті в журналах з теми "Bender element tests"
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Viggiani, Giulia, and J. H. Atkinson. "Interpretation of bender element tests." Géotechnique 45, no. 1 (March 1995): 149–54. http://dx.doi.org/10.1680/geot.1995.45.1.149.
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Chaney, RC, KR Demars, R. Arulnathan, RW Boulanger, and MF Riemer. "Analysis of Bender Element Tests." Geotechnical Testing Journal 21, no. 2 (1998): 120. http://dx.doi.org/10.1520/gtj10750j.
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Santamarina, J. C., and M. A. Fam. "Discussion: Interpretation of bender element tests." Géotechnique 47, no. 4 (September 1997): 873–77. http://dx.doi.org/10.1680/geot.1997.47.4.873.
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Jovičić, V., M. R. Coop, and M. Simić. "Objective criteria for determiningGmaxfrom bender element tests." Géotechnique 46, no. 2 (June 1996): 357–62. http://dx.doi.org/10.1680/geot.1996.46.2.357.
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Blewett, J., I. J. Blewett, and P. K. Woodward. "Phase and amplitude responses associated with the measurement of shear-wave velocity in sand by bender elements." Canadian Geotechnical Journal 37, no. 6 (December 1, 2000): 1348–57. http://dx.doi.org/10.1139/t00-047.
Повний текст джерелаАнотація:
Shear-wave velocity measured by bender elements in laboratory sand samples is shown to be dependent upon the excitation frequency and exhibits a maximum velocity for a finite frequency. By comparing the relative effects of dispersion due to propagation of shear waves through sand and dispersion due to bender element performance within sand, we show that a combination of the two processes is required to explain the observations. The magnitude of the aggregate response of the bender elements and the sand implies that reliable shear-wave velocity results cannot be obtained from bender element tests without a prior knowledge of the frequency response of the entire system.Key words: shear-wave velocity, phase-sensitive detection, dispersion, attenuation, sand.
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Piriyakul, Keeratikan. "Experimental Study on Elastic Stiffness of Kaolinite Clay." Advanced Materials Research 813 (September 2013): 395–98. http://dx.doi.org/10.4028/www.scientific.net/amr.813.395.
Повний текст джерелаАнотація:
This paper presents a study on the elastic shear modulus of Kaolinite clay at very small strains under isotropic stress from triaxial tests. The Kaolinite clay sample is subjected to an isotropic stress of 100, 200 and 400 kPa. In this very small strain domain where strain is less than 10-3 %, the behaviour of clay soil shows an elastic response. In conventional triaxial test, an initial shear modulus, G0, can be measured using an external strain measurement device. Nevertheless, there is an advantage to mount local strain sensors directly on a clay sample in order to obtain more accurate measurement of G0. Also the G0 can be measured by bender elements through propagation of an elastic shear wave. Therefore in this research G0 can be obtained by external, local strain measurements and bender element tests. These results of G0 in the very small strain region are compared and show that there is a good agreement between the results from local strain measurements and bender element tests.
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Youn, Jun-Ung, Yun-Wook Choo, and Dong-Soo Kim. "Measurement of small-strain shear modulus Gmax of dry and saturated sands by bender element, resonant column, and torsional shear tests." Canadian Geotechnical Journal 45, no. 10 (October 2008): 1426–38. http://dx.doi.org/10.1139/t08-069.
Повний текст джерелаАнотація:
The bender element method is an experimental technique used to determine the small-strain shear modulus (Gmax) of a soil by measuring the velocity of shear wave propagation through a sample. Bender elements have been applied as versatile transducers to measure the Gmax of wet and dry soils in various laboratory apparatuses. However, certain aspects of the bender element method have yet to be clearly specified because of uncertainties in determining travel time. In this paper, the bender element (BE), resonant column (RC), and torsional shear (TS) tests were performed on the same specimens using the modified Stokoe-type RC and TS testing equipment. Two clean sands, Toyoura and silica sands, were tested at various densities and mean effective stresses under dry and saturated conditions. Based on the test results, methods of determining travel time in BE tests were evaluated by comparing the results of RC, TS, and BE tests. Also, methods to evaluate Gmax of saturated sands from the shear-wave velocity (Vs) obtained by RC and BE tests were investigated by comparing the three sets of test results. Biot’s theory on frequency dependence of shear-wave velocity was adopted to consider dispersion of a shear wave in saturated conditions. The results of this study suggest that the total mass density, which is commonly used to convert Gmax from the measured Vs in saturated soils, should not be used to convert Vs to Gmax when the frequency of excitation is 10% greater than the characteristic frequency (fc) of the soil.
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Cheng, Z., and E. C. Leong. "Determination of damping ratios for soils using bender element tests." Soil Dynamics and Earthquake Engineering 111 (August 2018): 8–13. http://dx.doi.org/10.1016/j.soildyn.2018.04.016.
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O’Donovan, J., C. O’Sullivan, and G. Marketos. "Two-dimensional discrete element modelling of bender element tests on an idealised granular material." Granular Matter 14, no. 6 (October 6, 2012): 733–47. http://dx.doi.org/10.1007/s10035-012-0373-9.
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Rahman, Muhammad E., Vikram Pakrashi, Subhadeep Banerjee, and Trevor Orr. "Suitable Waves for Bender Element Tests: Interpretations, Errors and Modelling Aspects." Periodica Polytechnica Civil Engineering 60, no. 2 (2016): 145–58. http://dx.doi.org/10.3311/ppci.7952.
Повний текст джерелаДисертації з теми "Bender element tests"
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Johnson, Sean (Sean Michael). "Modeling a bender element test using Abaqus Finite Element Program." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/64573.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 253-255).
Finite Element Methods hold promise for modeling the behavior of an unsaturated soil specimen subjected to bender element agitation. The immediate objective of this research project is to reproduce a bender element test using Abaqus Finite Element Software assuming elastic and isotropic conditions. Extensive compressions were made of bender element testing of unsaturated Ticino Sand specimens uniaxially compressed and the Abaqus Finite Element Method program simulation. The research determined that the mesh resolution of a numerical analysis are optimal at a resolution of a twentieth of the shear wavelength and the integration time step has a negligible effect on the observed wave velocity. Moreover, it is possible to reproduce an uniaxially stressed bender element experiments of unsaturated Ticino sand in an Abaqus Finite Element Method program with relatively minimal error of the body wave velocity measurements if the source receiver distance is beyond two shear wavelengths and the reflected signals from the boundaries are suppressed.
by Sean Johnson.
S.M.
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Georgetti, Giovana Bizão. "Deformabilidade de um solo laterítico não saturado." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-20032015-103943/.
Повний текст джерелаАнотація:
A deformabilidade é uma propriedade fundamental em projetos geotécnicos. A constatação de que as deformações em várias obras de engenharia se situam na faixa de pequenas e muito pequenas deformações e as limitações das técnicas de ensaio em medir tal nível de deformações levaram ao desenvolvimento de técnicas com base em solicitações dinâmicas, dentre as quais, as de coluna ressonante e bender elements. Particularmente, o emprego da técnica de bender elements tem crescido devido à simplicidade de execução dos ensaios, e determinação do módulo de cisalhamento máximo dos solos. Diversos estudos acerca das propriedades deformacionais dos solos determinadas por este método têm sido conduzidos em solos saturados ou secos, não obstante, estudos desta natureza em solos não saturados ainda são relativamente escassos. Esta pesquisa investigou a influência de algumas variáveis, como a sucção e a tensão confinante sobre a deformabilidade de um solo laterítico não saturado típico do interior do Estado de São Paulo, empregando bender elements, coluna ressonante e compressão triaxial com instrumentação interna. Além disso, buscando uma caracterização mais completa deste solo, ensaios de compressão triaxial foram realizados para quantificar sua resistência ao cisalhamento. Os resultados destes ensaios sugeriram a ocorrência de encruamento em solo indeformado, e uma envoltória planar de resistência foi usada para representar a resistência ao cisalhamento da amostra compactada. Já no que se refere à deformabilidade, os resultados indicaram que a redução do teor de umidade de compactação, o aumento do confinamento isotrópico ou da sucção são responsáveis por um solo menos deformável. Dados dos ensaios com bender elements foram bem representados por uma função potencial quando o módulo de cisalhamento máximo e a sucção foram normalizados pela tensão confinante líquida. Para o solo compactado não saturado, também ensaiado em coluna ressonante, dados obtidos por ambas as técnicas foram comparados, notando-se velocidades de ondas de cisalhamento um pouco superiores para os ensaios com bender elements, que foram atribuídas às mais altas frequências nestes ensaios.Stiffness is a fundamental property in geotechnical design. The fact that strains are in the smallto- very small strain range in several engineering works and the limitations of testing techniques in measuring such level of strains led to the development of dynamic techniques, such as resonant column and bender elements. Specifically, the bender elements technique has been increasingly used due to the simplicity in performing tests and computing the maximum shear modulus of the soil. Several studies have been carried out to assess stiffness properties of dry or saturated soils via bender elements, however, studies of this nature are still relatively scarce in unsaturated soils. This research investigated the influence of some variables, like suction and confining stress, on the stiffness of a lateritic unsaturated soil, typical of São Paulo State, via bender elements, resonant column and triaxial compression tests with local gauges. Furthermore, aiming at a more complete characterization of this soil, triaxial compression tests were performed in order to quantify its shear strength. Results from these tests suggested the occurrence of strain hardening on undisturbed specimens, and a planar shear strength envelope was used to represent the compacted sample data. Regarding soil stiffness, results indicated that it increases with a reduction in the compaction moisture content or an increase in isotropic confining stress or suction. Data from bender elements tests were nicely represented by a power function when maximum shear modulus and suction were normalized by the net confining stress. Results of unsaturated compacted soil obtained from bender elements and resonant column tests were compared and slightly larger shear wave velocities were noticed in bender elements tests, which were attributed to the larger testing frequencies used in these tests.
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Santos, Roberto Aguiar dos. "Comportamento anisotrópico de um solo laterítico compactado." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-22032016-104302/.
Повний текст джерелаАнотація:
A compactação de aterros pode gerar comportamento anisotrópico, a depender do teor de umidade de compactação, entre outros fatores. O principal objetivo deste estudo foi investigar alguns aspectos relacionados à anisotropia inerente induzida pela compactação de um solo laterítico. Após realizar a caracterização mineralógica, geotécnica e microestrutural deste solo, estudou-se a resistência ao cisalhamento, condutividade hidráulica, compressibilidade e deformabilidade. O solo estudado foi classificado como laterítico arenoso (LA\') e apresentou agregação relativa da ordem de 12%. A metodologia desenvolvida no intuito de corrigir o aumento na massa específica seca das camadas inferiores, causado pelo processo de compactação, mostrou-se eficaz. A partir da curva de compactação foram consideradas amostras representativas das três condições de umidade de compactação: ramo seco, umidade ótima e ramo úmido. Corpos de prova foram talhados paralelamente e ortogonalmente às camadas de compactação. Os ensaios de porosimetria revelaram um comportamento bimodal na distribuição do tamanho de poros e também que o teor de umidade de compactação não interferiu no tamanho dos microporos. Para o solo compactado no ramo seco e na umidade ótima, a resistência ao cisalhamento correspondente à direção ortogonal se mostrou superior àquela correspondente à direção paralela às camadas de compactação. Por outro lado, a resistência ao cisalhamento no ramo úmido mostrou-se praticamente independente da direção de talhagem dos corpos de prova. Este comportamento se deve à maior capacidade do solo, em um dado teor de umidade, em absorver a energia aplicada e distribuí-la na direção paralela e ortogonal. Com relação às propriedades elásticas do material, observou-se que o aumento do teor de umidade de compactação contribui para redução da anisotropia de deformabilidade. Dentre as propriedades investigadas, a anisotropia de condutividade hidráulica das amostras correspondente ao ramo úmido foi a mais pronunciada, exibindo fluxo oito vezes maior na direção vertical que na horizontal. Finalmente, as discussões e análises presentadas nesta pesquisa mostraram que o grau de anisotropia depende diretamente do teor de umidade de compactação e que diminui com incremento das tensões aplicadas no solo.Compacted embankments can have anisotropic behavior, depending on several factors, including the compaction water content. The aim of this study was to investigate some aspects regarding the inherent anisotropy of a lateritic soil, caused by the compaction process. After performing the geotechnical, mineralogical and microstructural characterization, properties of shear strength, hydraulic conductivity, compressibility and deformability were investigated. This soil this soil was classified as lateritic sand. The grainsize distribution curve indicates 12% the fine particle aggregation. The methodology developed in order to correct the increase in dry density of the lower layers, generated by the compression process, was effective. From the compaction curve, representative samples corresponding to the three compaction water content conditions, representing the dry side, the optimal water content and the wet side were considered. Specimens were trimmed parallel and orthogonally to the compaction layers. The porosimetry tests showed a bimodal behavior in the pore size distribution and also that the compaction water content did not influence the size of the micropores. For the compacted soil sample corresponding to the dry side and optimum water content, the shear strength corresponding to the orthogonal direction was higher than that corresponding to the parallel direction to the compaction layers. However, they were almost equal for both the orthogonal and the parallel directions to the compaction layers. This behavior is due to the higher capacity of the soil at a given moisture content, to absorb the energy applied and distribute it in parallel and orthogonal direction. The analysis the values of maximum shear modulus of the material showed that increasing compaction water content reduces the anisotropy degree. Among the investigated properties, the hydraulic conductivity anisotropy of the samples corresponding to the wet branch was the most pronounced, showing permeability eight times higher in the vertical direction than that in the horizontal direction. Finally, the discussions and analyzes presented in this study showed that the degree of anisotropy directly depends on the compaction water content and decreases with increase confining stress applied to the soil specimens.
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Bedin, Jucélia. "Estudo do comportamento geomecânico de resíduos de mineração." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/26869.
Повний текст джерелаАнотація:
A extração e processamento de minério resultam na geração de elevadas quantidades de resíduos, cuja disposição gera impacto e risco ambiental. O lançamento direto em reservatórios contidos por diques consiste na forma mais comum de disposição dos resíduos de mineração em superfície. Estes diques podem ser construídos por alteamentos sucessivos a montante (upstream), prática desaconselhada em alguns países. Apesar de se tratar de um processo de baixo custo, o tipo de aterro a montante é uma operação de risco, pois a montante as barragens são sensíveis à liquefação e também porque a estabilidade das barragens pode ser ameaçada pelo excesso de poro pressão gerado dentro do depósito durante a construção. Para atender às exigências de projetos de áreas de disposição de resíduos é, portanto, fundamental entender o comportamento destes materiais. Resíduos exibem considerável variabilidade em suas características físicas, químicas e mineralógicas, que conferem um comportamento distinto dos geomateriais usualmente encontrados em depósitos naturais. Entre os diferentes resíduos destacam-se ouro e bauxita cuja prática de exploração no Brasil é revestida de considerável interesse econômico e ambiental. Nesta tese estes materiais são analisados a partir de uma extensa campanha de investigação geotécnica baseada em um programa de ensaios de laboratório destinados à caracterização destes resíduos e à definição de parâmetros constitutivos. Para fins comparativos são realizados ensaios com um material siltoso, porém inerte. A condutividade hidraúlica e compressibilidade dos resíduos foram obtidas através de ensaios oedométricos executados com estágios de carga e gradientes hidráulicos constantes. Ensaios triaxiais foram realizados com altos níveis de tensões de confinamento e distintas trajetórias de tensões, para a definição da linha do estado crítico e a identificação do comportamento destes materiais através de ensaios com Bender Elements. A análise dos resultados obtidos permitiu comparações entre a linha de consolidação oedométrica (LCO), a linha de consolidação isotrópica (LCI) e a linha do estado crítico (LEC) que definiram a resposta de liquefação estática do material. No espaço e - log (p´) o aparecimento de um comportamento instável alterou significativamente a inclinação da LEC com relação a LCI e a LCO. A mesma mudança de inclinação é observada tanto no parâmetro de estado como no módulo cisalhante do solo quando plotados contra a tensão efetiva média. Com base nessas evidências, é defendido que o LEC de resíduos de mineração é altamente não-linear, e servem como indicativo de três respostas distintas do solo: uma resposta estável quando LCO, LCI e a LEC exibem paralelismo, um comportamento meta-estável em baixas tensões de confinamento levando à liquefação e quebra de grãos para altas tensões de confinamento da amostra. O avanço nas pesquisas relativas à disposição de resíduos provenientes de indústrias de mineração com o conhecimento dos fenômenos que se processa, poderá evitar a ocorrência de ruptura de barragens, que teria como conseqüência desastres ambientais de grande impacto.Production and deposition of mining tailings is a problem confronting geotechnical engineers given the dimension of tailings deposits and environmental risks. The direct launching of tailings in reservoirs contained by dikes consists in a common type of waste disposal. These dikes can be constructed by successive upstream embankments, a relatively simple and economical process adopted in some countries. Although it is a low cost process, the upstream embankment is an operation of great risk, especially because tailings are susceptible to liquefaction and also because the stability of the dams can be threatened by excess of pore pressures generated inside the deposit during construction. To meet design requirements of disposal of residues it is therefore essential to understand the behavior of these materials. Tailings show a considerable variability in their physical, chemical and mineral characteristics that confer a distinct behavior to the geo-materials usually found in natural deposits. The present work gives emphasis to gold and bauxite tailings that encompass substantial economic and environmental interest in Brazil. In the thesis, an extensive laboratory geotechnical investigation program is carried out in an attempt to characterize these residues and to establish design constituent parameters. For comparative purposes an inert silty material is also tested. Compressibility and hydraulic conductivity were measured in oedometer tests performed at constant load and constant hydraulic gradient tests. Triaxial tests were carried out at high stress levels and different stress paths in order to establish the position and shape of the critical state line. In addition measured with Bender Elements are evaluated. The results between the oedometer consolidation (OCL), isotropic consolidation (ICL) and critical sate (CSL) lines allowed the static liquefaction response to be directly assessed. In a e-log (p’) space, the onset of a meta-stable behaviour significantly changes the slope of the CSL relative to both ICL and OCL. The same change in slope is observed on both the state parameter and the small strain shear modulus measured by bender elements when plotted against mean stress. Based on these evidences it is advocated that the CSL of the tailing is highly non-linear in nature, which lead to three distinct soil responses: a stable response when OCL, ICL and CSL exhibit similar slopes, a meta-stable beahaviour at lower stress leading to liquefaction and a crushable response for higher mean stresses. Advanced research on tailings from mining industries with due recognition of the phenomena of liquefaction may prevent dam failure, and consequently may prevent major environmental disasters.
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Bansod, Yogesh Deepak. "Computational Simulation of Mechanical Tests of Isolated Animal Cells." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-263397.
Повний текст джерелаАнотація:
Buňka tvoří složitý biologický systém vystavený mnoha mimobuněčným mechanickým podnětům. Hlubší pochopení jejího mechanického chování je důležité pro charakterizaci její odezvy v podmínkách zdraví i nemoci. Výpočtové modelování může rozšířit pochopení mechaniky buňky, která může přispívat k vytvoření vztahů mezi strukturou a funkcí různých typů buněk v různých stavech. Za tímto účelem byly pomocí metody konečných prvků (MKP) vytvořeny dva bendotensegritní modely buňky v různých stavech: model vznášející se buňky pro analýzu její globální mechanické odezvy, jako je protažení nebo stlačení, a model buňky přilnuté k podložce, který vysvětluje odezvu buňky na lokální mechanické zatížení, jako třeba vtlačování hrotu při mikroskopii atomárních sil (AFM). Oba zachovávají základní principy tensegritních struktur jako je jejich předpětí a vzájemné ovlivnění mezi komponentami, ale prvky se mohou nezávisle pohybovat. Zahrnutí nedávno navržené bendotensegritní koncepce umožňuje těmto modelům brát v úvahu jak tahové, tak i ohybové namáhání mikrotubulů (MTs) a také zahrnout vlnitost intermediálních filament (IFs). Modely předpokládají, že jednotlivé složky cytoskeletu mohou měnit svůj tvar a uspořádání, aniž by při jejich odstranění došlo ke kolapsu celé buněčné struktury, a tak umožňují hodnotit mechanický příspěvek jednotlivých složek cytoskeletu k mechanice buňky. Model vznášející se buňky napodobuje realisticky odezvu síla-deformace během protahování a stlačování buňky a obě odezvy ilustrují nelineární nárůst tuhosti s růstem mechanického zatížení. Výsledky simulací ukazují, že aktinová filamenta i mikrotubuly hrají klíčovou úlohu při určování tahové odezvy buňky, zatímco k její tlakové odezvě přispívají podstatně jen aktinová filamenta. Model buňky přilnuté k podložce dává odezvu síla-hloubka vtlačení ve dvou různých místech odpovídající nelineární odezvě zjištěné experimentálně při AFM. Výsledky simulací ukazují, že pro chování buňky je rozhodující místo vtlačení a její tuhost určují aktinová povrchová vrstva, mikrotubuly a cytoplazma. Navržené modely umožňují cenný vhled do vzájemných souvislostí mechanických vlastností buněk, do mechanické úlohy komponent cytoskeletu jak individuálně, tak i ve vzájemné synergii a do deformace jádra buňky za různých podmínek mechanického zatížení. Tudíž tato práce přispívá k lepšímu pochopení mechaniky cytoskeletu zodpovědné za chování buňky, což naopak může napomáhat ve zkoumání různých patologických podmínek jako je rakovina a cévní choroby.
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Aris, Mohamed. "Investigations expérimentales des effets de la microstructure sur le comportement des milieux granulaires et sur l'instabilité de liquéfaction." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4018.
Повний текст джерелаАнотація:
Le travail présenté dans ce mémoire a pour objectif d'aboutir à une meilleure caractérisation expérimentale du comportement non drainé du sable d'Hostun à l'échelle locale, en relation avec les différentes méthodes de reconstitution utilisées. On vise en particulier à mettre en évidence la façon dont la microstructure influence les propriétés des sols granulaires, notamment vis-à-vis de l'instabilité de liquéfaction. Le point clé de ce travail consiste en l'utilisation de capteurs piézoélectriques pour mesurer les vitesses d'onde de cisaillement au sein d'éprouvettes triaxiales reconstituées par trois techniques différentes à savoir le damage humide, la pluviation à sec et la pluviation sous eau. Les résultats obtenus mettent en évidence l'influence considérable du mode de fabrication sur le comportement mécanique du sable. Ils montrent que pour une même densité initiale, et à même pression de confinement, le comportement mécanique observé est très différent selon les trois modes de préparation. Les valeurs de vitesses d'onde de cisaillement enregistrées sont différentes d'un mode de déposition à un autre. Concernant l'anisotropie, le matériau préparé par damage humide présente un certain degré d'anisotropie inhérente, qui est toutefois minimal. En revanche, la pluviation à sec et la pluviation sous eau induisent des structures initiales plus isotropesThis work aims to achieve a better experimental characterization of the undrained behavior of the Hostun HN31 sand at the local scale, depending on the different procedures used for sample reconstitution. We particularly highlight the influence of the microstructure on the mechanical behavior of sand especially in relation to liquefaction instability. The key point of this work consists of the use of piezoelectric transducers to measure shear wave velocities within triaxial sand specimens. These specimens have been prepared by different methods, namely: moist tamping, dry pluviation and water pluviation. The obtained results highlight the considerable influence of the deposition mode on the mechanical behavior of sand. They show that for the same initial density, and at the same confining pressure, the mechanical behavior is very different from the three preparation methods. Furthermore, the values of shear wave velocity are different from one deposition mode to another. Concerning the anisotropy, the material prepared by moist tamping presents an inherent degree of anisotropy, which it is however minimal. On the other hand, dry pluviation and water pluviation induce more isotropic initial structures. Moreover, the initial anisotropy is less important than the anisotropy induced by loading. These experimental results indicate that the initial state of a granular medium can not be described by only couple of scalar variables of initial density and confining pressure: a variable that can reflect the initial microstructure and an evolution law of this variable are necessary to model the experimental observations
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Lin, Bao-Yan, and 林保延. "Estimation of the Dynamic Properties of Sands by Bender Element Tests." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/64988652901855787926.
Повний текст джерелаАнотація:
碩士國立臺灣科技大學
營建工程系
93
This research performed bender element tests with different frequencies of waves on Yaun-Lin sand and Hsin-Dian sand to study the effects of frequencies on the arriving time of shear wave; and the suitable range of frequencies was determined first. Then, bender element tests with suitable frequencies were carried out together with cyclic triaxial tests on Yaun-Lin sand to establish the relationship between shear wave velocity and liquefaction resistance. Test results showed that the arriving time of shear wave would be obviously underestimated and the signal received is very weak and hard to distinguish when the input frequency is below 5 kHz. When the input frequency is above 20 kHz, there would be larger errors in determination of the arriving time by different methods of analyses. There exists a quite good relationship between shear wave velocity and liquefaction resistance. Compared with the curves suggested by Andrus and Stokoe (1996), the liquefaction resistances estimated by bender element tests of this research are slightly higher than their results at the same shear wave velocities.
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Sanjeev, Shinde Ninad. "An Application of Resonant Column along with Bender Elements Tests for Assessing Dynamic Properties and Liquefaction Potential of Sand." Thesis, 2021. https://etd.iisc.ac.in/handle/2005/5654.
Повний текст джерелаАнотація:
For determining the response of foundation soils subjected to different kinds of vibrations emerging from (i) an occurrence of an earthquake, (ii) movements of trains over railways tracks, (iii) running of vehicles over roads, and (iv) continuous running of different types of the vibratory machines such as turbines, generators, and reciprocating engines, it is essential to know the dynamic properties of soils at different levels of strains and stresses. The resonant column and bender element tests have been extensively used over past few decades by numerous researchers for evaluating the dynamic properties of soils in a strain range of 0.0001 % to 0.1 %. In the present thesis, the resonant column and the bender elements tests have been employed to determine the dynamic properties (namely, elastic moduli and damping ratio) of not only soils (sand) but even for metal specimens as well to check the applicability of the tests for very stiff specimens. With a provision of continuous excitations, it was also attempted to extend the usage of the resonant column apparatus to examine the liquefaction potential of a fully saturated sand specimen. In addition, an attempt has also been made to introduce an automated predominant frequency-based approach to predict very accurately the arrival times of the waves while interpreting the bender elements tests results.
From the study of the received bender elements signals, it has been noted that, due to the presence of near field effects, it becomes a little difficult task to measure accurately the arrival point of the shear wave. The different available procedures in literature to mark the arrival times of the shear wave often require manual intervention and are often prone to errors. Therefore, it was aimed to develop an automated method to identify the time of the arrival of the shear wave. In the proposed method, the predominant frequency of the received signal was first evaluated and then, with the help of the sliding Fourier transform approach, the arrival time of the shear wave was identified. The main advantage of the proposed approach is that the method can be fully automated by following the algorithm which can be easily coded into a computer program, and it eliminates any manual judgement while determining the travel time. The proposed automated approach was applied to the bender element tests performed on dry and saturated sands by varying the input frequency of the signal, confining pressure, and void ratio. The results obtained from the proposed method were found to be very promising and were noted to be consistent with the data obtained on the basis of the resonant column tests
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Silva, Ana Rita Dias de Sousa e. "Numerical modelling of the dynamic behaviour of a soil in true triaxial tests with bender elements." Master's thesis, 2014. https://repositorio-aberto.up.pt/handle/10216/73440.
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Silva, Ana Rita Dias de Sousa e. "Numerical modelling of the dynamic behaviour of a soil in true triaxial tests with bender elements." Dissertação, 2014. https://repositorio-aberto.up.pt/handle/10216/73440.
Повний текст джерелаЧастини книг з теми "Bender element tests"
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Moldovan, Ionuţ Dragoş, Abdalla Almukashfi, and António Gomes Correia. "A Toolbox for the Automatic Interpretation of Bender Element Tests in Geomechanics." In Lecture Notes in Civil Engineering, 125–44. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-20241-4_10.
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Liu, Xin, and Jun Yang. "A Parallel Comparison of Small-Strain Shear Modulus in Bender Element and Resonant Column Tests." In Springer Series in Geomechanics and Geoengineering, 564–68. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-97112-4_126.
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Ferreira, Cristiana, António da Fonseca, and Jaime A. Santos. "Comparison of Simultaneous Bender Elements and Resonant Column Tests on Porto Residual Soil." In Soil Stress-Strain Behavior: Measurement, Modeling and Analysis, 523–35. Dordrecht: Springer Netherlands, 2007. http://dx.doi.org/10.1007/978-1-4020-6146-2_34.
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Banik, Nilanjana, and Rajib Sarkar. "Evaluation of Dynamic Properties of MICP-Treated Ennore Sand Through Bender Element Test." In Lecture Notes in Civil Engineering, 15–26. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1579-8_2.
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Piriyakul, Keeratikan, and Janjit Iamchaturapatr. "Deep Soil Mixing Method for the Bio-cement by Means of Bender Element Test." In Advances in Laboratory Testing and Modelling of Soils and Shales (ATMSS), 375–81. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-52773-4_44.
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Chandra, Kannekanti Prithvi, and Kadali Srinivas. "Estimation of Arrival Time of Shear Waves in Fine-Grained Soils Using Bender Element Test." In Lecture Notes in Civil Engineering, 213–32. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-3662-5_18.
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Hardy, S., L. Zdravkovi_, and D. Potts. "Numerical interpretation of continuously cycled bender element tests." In Numerical Models in Geomechanics, 595–600. Taylor & Francis, 2002. http://dx.doi.org/10.1201/9781439833797-c88.
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O'Donovan, J., C. O'Sullivan, and G. Marketos. "Micromechanics of Seismic Wave Propagation in Granular Materials." In Discrete Element Modelling of Particulate Media, 245–54. The Royal Society of Chemistry, 2012. http://dx.doi.org/10.1039/bk9781849733601-00245.
Повний текст джерелаАнотація:
This paper uses Discrete Element Method (DEM) simulations in order to obtain insight into the wave propagation mechanism through a granular material. A three dimensional face-centred cubic sample system was subjected to an isotropic confining stress. A seismic wave was generated by translating a single particle, in a situation analogous to a laboratory bender element test. The propagation of the wave-induced disturbance through the system was visualised by using particle scale methods such as plotting individual particle velocities and representative particle shear stresses. It was possible to compare the current study with previous research in the literature to identify different wave components. Arrival of the wave was found by tracking the displacement of a single particle in the sample (the receiver in a bender element test). Different travel time determination techniques available in the literature were used in an attempt to calculate an arrival time for the shear wave component and thus the velocity of the shear wave. The shear wave velocity was used to calculate a value for the shear modulus of the medium. A parametric study illustrating the effect of confining pressure on the sample shear modulus was carried out and agreement was found with theoretical predictions in the literature, even though the best way of identifying the wave travel time remains elusive.
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"Free type bender elements for characterizing soil in centrifuge model tests." In Physical Modelling in Geotechnics, Two Volume Set, 443–48. CRC Press, 2010. http://dx.doi.org/10.1201/b10554-70.
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Hori, T., S. Yamashita, and T. Suzuki. "Anisotropy of elastic moduli at small strain of sands and clays by bender element test." In Geomechanics and Geotechnics of Particulate Media, 41–47. CRC Press, 2017. http://dx.doi.org/10.1201/9781315106656-8.
Повний текст джерелаТези доповідей конференцій з теми "Bender element tests"
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Srikanth, C. S. S. U., B. J. Ramaiah, and Murali Krishna. "Laboratory Evaluation of Small Strain Elastic Parameters of Coal Ash from Bender Element Tests." In Geo-Congress 2023. Reston, VA: American Society of Civil Engineers, 2023. http://dx.doi.org/10.1061/9780784484678.050.
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Yamashita, Satoshi, Tomohito Hori, and Teruyuki Suzuki. "Anisotropic Stress-Strain Behavior at Small Strains of Clay by Triaxial and Bender Element Tests." In Second Japan-U.S. Workshop on Testing, Modeling, and Simulation in Geomechanics. Reston, VA: American Society of Civil Engineers, 2006. http://dx.doi.org/10.1061/40870(216)4.
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Chen, Y. M., and Y. G. Zhou. "Technique Standardization of Bender Elements and International Parallel Test." In GeoShanghai International Conference 2006. Reston, VA: American Society of Civil Engineers, 2006. http://dx.doi.org/10.1061/40862(194)11.
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Sen, Millan, and Roger Cheng. "Finite Element Analysis of Cold Bend Pipes Under Bending Loads." In 2010 8th International Pipeline Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ipc2010-31487.
Повний текст джерелаАнотація:
Cold bends are required in pipelines at locations of changes in horizontal or vertical direction in the right of way. Due to this change of direction, pipeline deformations caused by geotechnical or operational loading conditions tend to accumulate at the site of cold bends. These deformations may become sufficient to cause local buckling at the bend. For pipeline design, it is important to understand the level of deformation that a cold bend can accumulate prior to local buckling so that the strain capacity can be compared to the expected pipeline deformations. Evaluating the buckling strain of cold bends is extremely complex due to the residual stresses, ripples, and material transformations cause by the cold bending process. Accordingly a finite element model was developed herein. This model accounted for the cold bend geometry, initial imperfections, and the material transformations caused by the cold bending process. This model was validated against 7 full scale tests of cold bend pipes that were subjected to bend loading and internal pressure. The global and local behavior of this model exhibited reasonable correlation against the tests.
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Zeng, L., A. Börjesson, and L. G. Jansson. "Further Tests on Pipe Elements in Commercial Software for Nuclear Power Piping Analysis." In ASME 2015 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/pvp2015-45548.
Повний текст джерелаАнотація:
The paper reports our further numerical tests on pipe elements in some commercial software for nuclear power piping analysis. Following our earlier tests on pipe elements, numerical tests are conducted using ANSYS, ABAQUS and PIPESTRESS with focus on the accuracy and reliability of key solutions: eigen-frequencies, reaction forces, stresses in pipe bends, deformation and others due to both static and dynamic loads. Benchmark examples are considered: (1) A simple pipe bend with varying wall-thicknesses; (2) A pipe model with two bends; (3) An irregular pipe model. A comparison against computations using elbow and shell elements is reported. The results indicate that analyses using traditional beam elements can go wrong and cautions are necessary, which is of particular importance for cases when extreme flexible piping systems are dealt with. It is concluded that there is a great need for advanced finite element computation for achieving a more reliable and accurate piping analysis.
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Huang, Lin, Yong Wang, Jian Li, Wei He, and Xian-qin Li. "The Effect of Different Boundary Conditions on the Result of Bender-Extender Element Test." In International Conference on Geotechnical and Earthquake Engineering 2018. Reston, VA: American Society of Civil Engineers, 2019. http://dx.doi.org/10.1061/9780784482049.041.
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Kim, Young Suk, and Don R. Metzger. "A Finite Element Study of Friction Effect in Four-Point Bending Creep Test." In ASME 2003 Pressure Vessels and Piping Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/pvp2003-1894.
Повний текст джерелаАнотація:
Creep tests are often performed in four-point bending and the stress distribution in the bending specimen is nonlinear, so creep properties are estimated from bend creep test data. However, getting creep properties from bending creep tests is often doubted because of uncertainties from contact point shift and frictional effect between loading pin and specimen in four-point bending creep tests. Finite element simulations of the four-point bending creep tests were performed with geometric models which include contact conditions. It was found from simulation studies that friction in the bend tests can cause error in the estimation of creep properties, but when no friction was applied in simulations the creep properties were well predicted from bend test data.
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Zeng, Lingfu, Lennart G. Jansson, and Yordan Venev. "On Pipe Elbow Elements in ABAQUS and Benchmark Tests." In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28920.
Повний текст джерелаАнотація:
In this paper, elbow elements in commercial finite element software ABAQUS are reviewed and two commonly used elements, ELBOW31 (2-node, linear) and ELBOW32 (3-node, quadratic), are numerically tested for two Benchmark examples: a cantilever pipe and an in-plane bending pipe bend. Two main issues are studied through the numerical tests: (1) The effect of the element size and the number of ovalization modes chosen for computation; (2) The accuracy of computed deformation and stresses. To gain an insight into the behavior of these elements, a comparison against published results by experiment and computations using elbow elements in software ADINA and MARC, as well as computations using ABAQUS shell elements, is conducted. It is shown that: (i) these elements predict a good peak stress solution with a reasonably coarse mesh and 6 ovalization modes; (ii) the ovalization and the distribution of stresses predicted around the pipe section show, though using a relatively dense mesh, a notable difference as compared to solutions computed by ABAQUS shell elements; (iii) the ADINA elbow element seems to provide, though using a very coarse mesh, a solution closest to analytic and experimental results. It is concluded that there are great needs for in-depth studies on elbow elements regarding reliability and accuracy issues.
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Yamashita, Satoshi, Tomohito Hori, and Teruyuki Suzuki. "Effects of Initial and Induced Anisotropy on Initial Stiffness of Sand by Triaxial and Bender Elements Tests." In First Japan-U.S. Workshop on Testing, Modeling, and Simulation. Reston, VA: American Society of Civil Engineers, 2005. http://dx.doi.org/10.1061/40797(172)20.
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Ligon, Thomas C., David J. Gross, and John C. Minichiello. "Correlation of Piping System Detonation Test Data and System Analyses." In ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78526.
Повний текст джерелаАнотація:
This paper describes hydrogen and nitrous oxide detonation experiments that were performed using an approximately 200-ft long 2-inch schedule 40 piping system. The objective of these experiments was to develop an understanding of the loads and forces imposed by internal detonation on piping combinations representative of a typical industrial piping system. The apparatus contained numerous straight pipe lengths with 90° and 45° bends, 90° elbows, and a tee along with rigid foundation supports that were connected to the pipe using typical u-bolt fasteners. As a detonation wave propagates through a gas-filled piping system, the pipe begins to respond globally once a detonation encounters a change in flow direction, such as a bend, causing a pressure imbalance due to both the internal detonation pressure and change in momentum of the reaction products. The resultant force imparts both axial forces and moments on the pipe exciting both extensional and bending modes. The test data was used to validate two finite element (FE) models developed using the ANSYS finite-element program: a hybrid model that made use of both shell and beam elements, to determine the interaction between shell and beam modes, and an all beam element model. An additional beam element model was developed using the Bechtel National Inc. software ME101 that was also found to be in agreement with the measured and ANSYS calculated frequencies and support loads. In addition to the detonation testing, the finite-element models were validated against experimental modal analysis data of the piping system that identified the primary modal frequencies and vectors. These data were compared to the modes extracted from finite-element models of the piping system.
Звіти організацій з теми "Bender element tests"
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Graville. L51764 Hydrogen Cracking in the Heat-Affected Zone of High-Strength Steels-Year 2. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), March 1997. http://dx.doi.org/10.55274/r0010170.
Повний текст джерелаАнотація:
During year 1 of this project a test to evaluate the sensitivity of the heat affected zone (HAZ) to hydrogen cracking was developed. This was in response to a need for a test which provided unambiguous results in contrast to existing test methods which often led to difficulties in interpretation. For example, WIC tests usually cracked in the weld metal rather than the HAZ and therefore did not produce a clear indication of the sensistivity of the HAZ. The new test involves a machined notch which can be placed in the HAZ thus forcing crack initiation to occur in the desired region. A further advantage of the new test is that it is quantitative with each test specimen providing a measure of the sensitivity of the HAZ in that test. Existing tests are usually of the crack/no-crack type requiring a series of tests at different preheats to be carried out in order to establish a critical value. This is an expensive, time-consuming approach. The new test measures the deflection to first load drop (normally the onset of significant cracking) when the welded specimen is loaded in bending. It was also shown during the first year of the project that the simple geometry of the test lends itself to easy analysis enabling the stress/strain distribution to be calculated by finite element analysis. The quantitative measurement of susceptibility in the test enabled the cracking of more complex welds to be predicted on the basis of a local critical hydrogen model. The objective of the work was to extend the notched bend test to the evaluation of weld metal sensitivity to hydrogen cracking. The experiments were designed to determine whether the test could discriminate between two different weld metals and to study the effects of reducing hydrogen content. In addition, finite element analysis of the weld metal test was carried out and finite difference analysis used to predict the local hydrogen concentration. This work modifies the notched bend test, developed for evaluating the sensitivity of the heat affected zone (HAZ), to allow the evaluation of weld metal. The results showed that weld metal could readily be evaluated, with the test discriminating among weld metals of different composition and hydrogen contact. Finite element analysis was undertaken and showed that for the two weld metals tested, cracking occurred at the same local stress when the hydrogen content was the same, despite differences in strength. A finite model was used to calculate the distribution of hydrogen as a function of aging time. Although the general trends were confirmed by the experimental measurements of hydrogen content, there was considerable scatter attributed to the small hydrogen volumes measured.
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Rosenfeld, Hart, and Zulfiqar. L51994 Acceptance Criteria for Mild Ripples in Pipeline Field Bends. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), September 2003. http://dx.doi.org/10.55274/r0010395.
Повний текст джерелаАнотація:
Field bends in large diameter pipe are routinely used in the construction of oil and gas pipelines. Mild ripples along the intrados are often unavoidable where such bends have a high D/t or high yield strength. Present regulations and industry standards differ in their treatment of mild ripples, ranging from silence to prohibition, depending upon interpretation. Consequently, the application of acceptance standards for such features is inconsistent, leading to variable standards of inspection and probable scrapping of otherwise sound bends. Finite element analysis (FEA) was used to estimate the effect of ripple magnitude and spacing on stresses due to pressure and bending. Stress concentration factors derived from the models were used with a suitable fatigue damage rule to estimate the effect of ripple parameters on service life. Results were benchmarked against the available test data. The results indicate that (1) mild or shallow ripples up to 2 percent of the pipe diameter in crest-to-trough dimension would not be expected to be harmful in gas transmission pipelines operating under conditions normally encountered in the gas transportation industry; (2) mild or shallow ripples up to 1 percent of the pipe diameter in crest-to-trough dimension would not be expected to be harmful in hazardous liquid transportation pipelines operating under conditions normally encountered in the liquid transportation industry; (3) the presence of ripples could eventually be harmful to long-term integrity in a severe cyclic loading (pressure, thermal expansion, flow-induced vibration) environment, or where soil movement could take place. Recommendations are made for ASME Code criteria specifically permitting mild ripples within stated limits.
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Shen, Gianetto, and Tyson. L52342 Development of Procedure for Low-Constraint Toughness Testing Using a Single-Specimen Technique. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), December 2011. http://dx.doi.org/10.55274/r0010687.
Повний текст джерелаАнотація:
Pipelines from remote frontier regions are increasingly required to have adequate resistance to large deformations such as that caused by ground movement. In response to this, �strain-based design"� has been developed to enable assessment of imperfections at applied strains beyond yield. In addition, it is proposed to take advantage of the increased apparent toughness of pipe under low constraint, such as girth weld imperfections under axial tension, compared with the high-constraint toughness measured in conventional tests such as ASTM E1290 [1]. Application of low-constraint testing has been dvantageously applied in assessment of toughness for offshore pipeline projects. Also in the pipeline industry, demands on new pipeline projects include low design temperatures as well as high strain capacity. At the same time, increased strength is specified, which increases the level of required toughness. These factors make it increasingly important to assure weldment toughness, in particular to ensure that the failure mode remains ductile. It is well known that brittle cleavage is especially sensitive to constraint, and the availability of a toughness test that would reproduce field conditions would enable more rational development and acceptance of candidate welds and, in particular, enable more appropriate testing of weld heat-affected zones. This work was performed for specific application to surface circumferential cracks in pipe under strain-based design, for which the best constraint matching has been found to occur for clamped single-edge tension (SE(T)) specimens with H/W=10. For this geometry, a test procedure similar to that of ASTM E1820-06 for single-edge bend (SE(B)) and compact tension (C(T)) specimens was developed for J-resistance tests using a single-specimen technique. All the equations used in the procedure, including those for evaluation of J-integrals from the area under load/plastic crack mouth opening displacement (CMOD) curves, and evaluation of crack length from unloading compliance including rotation correction, were developed using finite element analysis (FEA) with a range of crack depths, focusing on a/W= 0.2 to 0.5 which is of most practical interest. The present procedure is compared with that of E1820 for SE(B) testing regarding evaluation of J-integral with crack growth correction, crack length evaluation, and correction of compliance for rotation.