A Soil-Tool Model Based on Limit Equilibrium Analysis

Perumpral, John V.; Grisso, Robert D.; Desai, C. S.

doi:10.13031/2013.34062

Cited by 72 publications

(39 citation statements)

References 7 publications

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“…The methods of Coulomb [2] and Perumpral [3,4] assume that the material in front of the blade fails and moves as a rigid body. The sum of all forces acting on this rigid body can be used to solve for the forces acting on the blade.…”

Section: Methodsmentioning

confidence: 99%

Discrete and continuum modelling of soil cutting

Coetzee

2014

Comp. Part. Mech.

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Both continuum and discrete methods are used to investigate the soil cutting process. The Discrete Element Method (dem) is used for the discrete modelling and the Material-Point Method (mpm) is used for continuum modelling. Mpmis a so-called particle method or meshless finite element method. Standard finite element methods have difficulty in modelling the entire cutting process due to large displacements and deformation of the mesh. The use of meshless methods overcomes this problem. Mpm can model large deformations, frictional contact at the soil-tool interface, and dynamic effects (inertia forces). In granular materials the discreteness of the system is often important and rotational degrees of freedom are active, which might require enhanced theoretical approaches like polar continua. In polar continuum theories, the material points are considered to possess orientations. A material point has three degrees-of-freedom for rigid rotations, in addition to the three classic translational degrees-of-freedom. The Cosserat continuum is the most transparent and straightforward extension of the nonpolar (classic) continuum. Two-dimensional dem and mpm (polar and nonpolar) simulations of the cutting problem are compared to experiments. The drag force and flow patterns are compared using cohesionless corn grains as material. The corn macro (continuum) and micro (dem) properties were obtained from shear and oedometer tests. Results show that the dilatancy angle plays a significant role in the flow of material but has less of an influence on the draft force. Nonpolar mpm is the most accurate in predicting blade forces, blade-soil interface stresses and the position and orientation of shear bands. Polar mpm fails in predicting the orientation of the shear band, but is less sensitive to mesh size and mesh ori-C. J. Coetzee (B) Department of Mechanical and Mechatronic Engineering, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa e-mail: ccoetzee@sun.ac.za entation compared to nonpolar mpm. dem simulations show less material dilation than observed during experiments.

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Section: Methodsmentioning

confidence: 99%

Discrete and continuum modelling of soil cutting

Coetzee

2014

Comp. Part. Mech.

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“…8. This has been done by Perumpral et al [23] for 3D systems and for a tool inclined at an angle β to the horizontal and with an angle of friction δ and for the Coulomb failure criterion with cohesion. This model assumes that the deformation is localized on a plane passing through the bottom of the tool and making an angle ρ with the horizontal.…”

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confidence: 99%

“…8. Geometry of the mobilized domain considered by Perumpral et al according to [23] where h 1 and h 2 have the same meanings as in Fig. 6.…”

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confidence: 99%

Force fluctuations in a pushed granular material

Nouguier

Bohatier

Moreau

et al. 2000

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“…Deve-se lembrar, então, que a equação apresentada foi obtida com o escarificador, trabalhando com três hastes. Várias referências demonstram que a variação da força de tração, em função da profundidade de trabalho, é representada por uma expressão quadrática (Kiss & Bellow, 1981;Perumpral et al, 1983 e American Society of Agricultural Engineer, 1990). O coeficiente quadrático da expressão obtida para a força de tração na barra é pequeno, da ordem de 0,1; no entanto, significativo a nível de 0,01 de probabilidade.…”

Section: Resultsunclassified

Comportamento Operacional De Um Escarificador De Hastes Parabólicas Em Solo De Cerrado

Bianchini

Sabino

Borges³

et al. 1999

Rev. bras. eng. agríc. ambient.

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RESUMOO escarificador é um importante implemento de preparo primário de solo, embora nem sempre utilizado nos cerrados de forma correta, em função do pouco conhecimento que se tem a respeito de seu comportamento. Assim, instalou-se, na Escola Agrotécnica Federal de Cuiabá, um experimento com o objetivo de se avaliar o desempenho de um escarificador de hastes parabólicas no preparo primário de um solo de cerrado e obter equações que possam prever a força de tração e a potência exigidas; a área constituía-se de um Latossolo Vermelho-Amarelo, com 14,3% de argila, de cobertura vegetal média de 9.975 kg ha -1 de matéria seca e de um teor médio de umidade de 13%. Os resultados obtidos mostram que os parâmetros força de tração, área mobilizada e resistência específica, não sofreram influência com a variação da velocidade, a potência aumentou e a energia consumida (kWh ha -1 ) diminuiu com o aumento da velocidade. A força de tração, a potência na barra e a resistência específica do solo apresentaram comportamento quadrático, em função da profundidade de preparo. A área de seção transversal de solo mobilizado apresentou comportamento linear com a variação da profundidade de operação do escarificador. A melhor eficiência, de 85,69%, foi obtida para a relação largura/profundidade de operação igual a 1,23, e a equação de McKeys, com o fator de correção de 1,08, foi eficiente para predizer a área mobilizada efetiva. Palavras-chave: força de tração, potência, área mobilizada, eficiência PERFORMANCE OF A PARABOLIC CHISEL PLOW IN A SOIL OF "CERRADO" ABSTRACTThe chisel plow is an important implement for tillage, but it is not always used correctly in the "Cerrados", due to limited availability of knowledge on the behavior of the chisel plow in these soils. An experiment was set up at the "Escola Agrotécnica Federal de Cuiabá" with the objective of evaluating the action of a chisel plow, with a parabolic stem, in "Cerrado" soil. The plots were set on a "Latossolo Vermelho-Amarelo", with 14.3% clay, under a mulch blanketing of 9.975 kg ha -1 (DM) and 13% soil moisture. The results show that the mobilized area and the specific resistance were not influenced by speed variation. The power increased and the energy consumption (kWh ha -1 ) decreased with the increase of the speed. The pull traction, power and the soil specific resistance varied quadratically with tillage depth, while the cross section at area of mobilized soil presented a linear behavior. The best efficiency of 85.69%, was obtained for the relation width/depth = 1.23. The equation of McKeys, with a correction factor of 1.08, was efficient for the prediction of the effectively mobilized area.

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A Soil-Tool Model Based on Limit Equilibrium Analysis

Cited by 72 publications

References 7 publications

Discrete and continuum modelling of soil cutting

Discrete and continuum modelling of soil cutting

Force fluctuations in a pushed granular material

Comportamento Operacional De Um Escarificador De Hastes Parabólicas Em Solo De Cerrado

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