Forças verticais e de atrito em silos cilíndricos com fundo plano

Neto, José Pinheiro Lopes; Nascimento, José Wallace Barbosa do; Fank, Marivone Z.

doi:10.1590/s1415-43662014000600013

Cited by 8 publications

(5 citation statements)

References 10 publications

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“…Amorphous solids promoting larger points of contact between particles and walls, consequently compromising the powders' flow. According to Lopes Neto et al (2014), the greater the roughness of the surface of the particle and/or the wall, the larger the frictional force absorbed by it. For spray drying samples with 15% maltodextrin, the opposite effect was observed.…”

Section: Resultsmentioning

confidence: 99%

Flow behavior of cocoa pulp powder containing maltodextrin

Ribeiro

Costa

Afonso

2020

Braz. J. Food Technol.

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This study aimed to evaluate the influence of maltodextrin addition on the flow properties of cocoa pulp powder obtained by spray and freeze drying. Cocoa pulp samples received 15% and 30% (m m-1) maltodextrin DE20. Two drying methods were used, spray and freeze drying. Powder morphology was evaluated through scanning electron microscopy (SEM). Wall friction angle, bulk density and tapped density were determined. Carr index (CI), Hausner ratio (HR) and flow index (FI) were used to evaluate powder flow. The particles powders obtained by spray drying showed rounded shapes, whereas the freeze dried powder showed irregular shapes. Increased maltodextrin concentration in the samples altered the powder particle size by spray drying and powder particle surface by freeze drying. The powder by spray drying of the sample with 30% of maltodextrin showed smallest wall friction angles, 13.4 to 14.9. The powder by freeze drying of the samples with 15% and 30% of maltodextrin showed wall friction angles between 14.0 and 20.6. Regarding flow, the powders by spray drying containing 30% of maltodextrin showed the best CI, HR and FI, 24.88, 1.33 and 4.88, respectively, being considered an acceptable flow. According to CI, HR and FI values, samples with 15% of maltodextrin produced powder classified as difficult flow in both methods applied. The higher maltodextrin concentration in cocoa pulp, the lower agglomeration in the powder by spray drying and the smoother particles surfaces in the powder by freeze drying. The addition of maltodextrin to the samples, for both drying methods, improve the powder flow and decrease the powder cohesion.

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Section: Resultsmentioning

confidence: 99%

Flow behavior of cocoa pulp powder containing maltodextrin

Ribeiro

Costa

Afonso

2020

Braz. J. Food Technol.

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“…Lopes Neto et al (2014a) carried out a theoreticalexperimental analysis in a model silo with dry sand stored as a product, noting that the values of vertical pressures for the concentric unloading of the AS 3774 and ISO 11697 (1995) standards were the most adequate but 15% higher than the experimental values. When analyzing the efforts in a cylindrical silo with H/D ratio equal to 2, Couto et al (2013) observed that the values calculated by the recommendations of EN 1991-4 standard also overestimated the experimental results.…”

Section: Resultsmentioning

confidence: 99%

“…The large number of variables involved hampers a mathematical formalism capable of adequately expressing the phenomenon and that is applied with an acceptable margin of safety and economy (Calil Júnior et al, 2009). Many studies have been developed for the determination of pressures in silos using Janssen's theory (Lopes Neto, 2009;Nascimento & Calil Junior 2009;Ramírez et al, 2010;Ding et al, 2011;Silva et al, 2011;Lopes Neto et al, 2014a), however, in Brazil, the calculation procedures are not standardized.…”

Section: Introductionmentioning

confidence: 99%

Vertical Pressures and Compressive Friction Force in a Large Silo

et al. 2018

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The grain flow is a dynamic phenomenon of high non-linearity, responsible for the occurrence of a high index of structural problems in silos, assuming particular interest in Brazil because the country does not have a standard of design of these structures. In order to determine the transfer of loads to the foundations, a silo in true magnitude was instrumented through pressure cells in the reinforced concrete slab of the bottom and through load cells under two of its column. The experiment was conducted during the period from December 2016 to February 2017 in Entre Rios do Oeste-PR. The profiles of vertical and the compression friction pressures were obtained during the loading, storage and unloading phases of corn grains. The vertical pressure distribution in the silo bottom was shown to be variable along its radius, in accordance with the formulation of the AS 3774 standard, an alternative to the simplified uniform distribution hypothesis prescribed by the EN 1991-4 and ANSI/ASAE EP433 standards. We also observed experimentally the non-occurrence of overpressure at the unloading of the silo under analysis. The load transfer coefficient to the column was 0.35, being that the ANSI/ASAE EP433, EN 1991-4 and AS 3774 standards increased this transfer by 6.57%, 35.91% and 75.03% respectively, reflecting the great divergence between these prescriptions.

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“…Studies have been conducted with reference to the determination of pressures acting on flat bottom silos (Diniz & Nascimento, 2006;Balevičius et al, 2011;Gallego et al, 2011;Rotter & Sadowski, 2012;Nascimento et al, 2013;Lopes Neto et al, 2014;Wen et al, 2015;Horabik et al, 2016;Wang et al, 2016;Pieraccini et al, 2017;Frank et al, 2018). However, there is a need for studies on the use of new materials for the flat bottom of these silos, which are elements subject to dynamic, often non-uniform loads.…”

Section: Introductionmentioning

confidence: 99%

Fiber-reinforced concrete for the flat bottom of silos

Constantino

Neto

Nóbrega

et al. 2020

Rev. bras. eng. agríc. ambient.

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The use of synthetic fibers as reinforcement for concrete replacing the steel reinforcement has been diffused worldwide in several applications, gaining prominence in the application for industrial floors, tunnel linings, road pavements, etc., i.e., continuous structures in contact with soil that require performance in the elastic medium. The present study investigated the applicability of concrete reinforced with synthetic fibers in the bottom slab of silos supported directly on the ground, being composed of an experimental study and a case study. The experimental study consisted of the analysis of the mechanical behavior of this concrete by testing three concentrations of synthetic fibers (3.0, 4.5 and 6.0 kg m -3 ) in a conventional simple concrete matrix. The case study consisted of the design of this part in conventional reinforced concrete and concrete reinforced with synthetic fibers with the objective of performing an economic comparison between the two projects. The experimental results showed that the fiber concentration that contributed to a better mechanical performance of the concrete matrix was 3.0 kg m -3 . The case study showed that the most economical design was the one made with fiber-reinforced concrete.Concreto reforçado com fibras para o fundo plano de silos RESUMO: O emprego de fibras sintéticas como reforço para concretos em substituição das armaduras de aço vem sendo difundido mundialmente em diversas aplicações, ganhando destaque na aplicação para pisos industriais, revestimentos de túneis, pavimentos rodoviários, etc., isto é, estruturas contínuas em contato com o solo que requerem desempenho no meio elástico. O presente trabalho investiga a aplicabilidade do concreto reforçado com fibras sintéticas na laje de fundo de silos apoiados diretamente sobre o solo, sendo o mesmo composto por um estudo experimental e um estudo de caso. O estudo experimental resume-se na análise do comportamento mecânico desse concreto, testando-se três concentrações de fibras sintéticas (3.0, 4.5 e 6.0 kg m -3 ) numa matriz de concreto simples convencional. O estudo de caso consiste no dimensionamento dessa peça em concreto armado convencional e concreto reforçado com fibras sintéticas, com o objetivo de realizar um comparativo econômico entre os dois projetos. Os resultados experimentais mostraram que a concentração de fibras que contribuiu para melhor desempenho mecânico da matriz de concreto foi o de 3.0 kg m -3 . O estudo de caso mostrou que o projeto mais econômico foi o dimensionado com concreto reforçado com fibras. Palavras-chave: comportamento mecânico, dimensionamento, materiais alternativos

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Forças verticais e de atrito em silos cilíndricos com fundo plano

Cited by 8 publications

References 10 publications

Flow behavior of cocoa pulp powder containing maltodextrin

Flow behavior of cocoa pulp powder containing maltodextrin

Vertical Pressures and Compressive Friction Force in a Large Silo

Fiber-reinforced concrete for the flat bottom of silos

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