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Papers by Gabriel de Oliveira Ribeiro

Current Opinion in Anesthesiology, 2012

Rodrigo G. Peixoto Samuel S. Penna Gabriel O. Ribeiro Roque L. S. Pitangueira rodrigo.peixoto@dee... more Rodrigo G. Peixoto Samuel S. Penna Gabriel O. Ribeiro Roque L. S. Pitangueira rodrigo.peixoto@dees.ufmg.br spenna@dees.ufmg.br gabriel@dees.ufmg.br roque@dees.ufmg.br Dep. de Eng. de Estruturas, Escola de Engenharia, Universidade Federal de Minas Gerais Avenida Antônio Carlos, 6627, CEP: 31270-901, Belo Horizonte, Minas Gerais, Brazil Abstract. The conventional (local) constitutive modelling of materials exhibiting strain softening behaviour is suceptive to a spurious mesh dependence caused by numerically induced strain localization. Also, for very refined meshes, numerical instabilities may be verified, mainly if the simulations are performed by the boundary element method. An alternative to overcome such difficulties is the adoption of the so called non-local constitutive models. In this approach, some internal variables of the constitutive model in a single point are averaged considering its values of the neighbouring points. In this paper, the implicit formulation of the boundar...

Proceedings of the XXXVIII Iberian Latin American Congress on Computational Methods in Engineering, 2017

The failure analysis in structures is extremely important since it allows to evaluate the safety ... more The failure analysis in structures is extremely important since it allows to evaluate the safety degree and the integrity of structural systems. However, despite the increasing use of numerical methods in the study of material failures in the last years, the boundary element method is still little used when compared to domain methods. Thus, in this work it is analyzed the failure mechanics in some classical problems through the continuum strong discontinuity approach. In this way, it is used the implicit formulation of the boundary element method for nonlinear problems to shown the dependence of the step size when the cells with embedded discontinuity are generated only after step convergence or during any iteration, respectively, in the incremental-iterative process. For this purpose, the same problem was analyzed considering these two cases and also different numbers of steps. It was verified that the results are coincident for all numbers of steps considered in the simulations when cells are generated during any iteration, showing step size independence in this case, while the same is not true for the case of cells generated only after convergence, in which a large numbers of steps is required for well accuracy.

Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015

Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015

Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2014

Revista Brasileira de Zootecnia, 2014

The purpose of this study was to evaluate the voluntary intake and digestibility of three sorghum... more The purpose of this study was to evaluate the voluntary intake and digestibility of three sorghum (Sorghum bicolor, L. Moench) hybrid silages in sheep. The hybrids used were H1 -BRS 655 (CMSXS 222 A × CMSXS 235 R), with tannin; H2 -(ATF54 A × CMSXS 235 R), without tannin; and H3 -BRS 610 (CMSXS 232 A × CMSXS 234 R), without tannin. The intake and digestibility of dry matter (DM), gross energy (GE), neutral detergent fiber (NDF), acid detergent fiber (ADF) and crude protein (CP) were measured. Eighteen crossbred sheep weighing 59.4 kg (±8.3) were used in the trial. A completely randomized design with three treatments (hybrids) and six repetitions (sheep) was used. There were no differences in the DM intake or apparent digestibility among the hybrids. Silage of hybrid BRS 610 displayed higher digestibility coefficients for CP, NDF, ADF, and GE compared with the other silages, which did not differ from each other. The neutral detergent fiber, ADF and digestible energy (DE) intakes were similar among the hybrids silages. All of the hybrids resulted in a positive N balance in sheep. The levels of DE were superior in hybrid silage BRS 610 in comparison with the other hybrids. Sorghum hybrid BRS 610 silage exhibited superior nutritional value compared with the other hybrids, which is most likely in part due to the absence of tannins. Sorghum silage made with hybrid BRS 610 (CMSXS 232 A × CMSXS 234 R) presents superior gross energy, crude protein, neutral detergent fiber and acid detergent fiber digestibility coefficients, as well as greater digestible energy levels than BRS 655 (CMSXS 222 A × CMSXS 235 R) and (ATF54 A × CMSXS 235 R).

Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015

Current Opinion in Anesthesiology, 2012

Rodrigo G. Peixoto Samuel S. Penna Gabriel O. Ribeiro Roque L. S. Pitangueira rodrigo.peixoto@dee... more Rodrigo G. Peixoto Samuel S. Penna Gabriel O. Ribeiro Roque L. S. Pitangueira rodrigo.peixoto@dees.ufmg.br spenna@dees.ufmg.br gabriel@dees.ufmg.br roque@dees.ufmg.br Dep. de Eng. de Estruturas, Escola de Engenharia, Universidade Federal de Minas Gerais Avenida Antônio Carlos, 6627, CEP: 31270-901, Belo Horizonte, Minas Gerais, Brazil Abstract. The conventional (local) constitutive modelling of materials exhibiting strain softening behaviour is suceptive to a spurious mesh dependence caused by numerically induced strain localization. Also, for very refined meshes, numerical instabilities may be verified, mainly if the simulations are performed by the boundary element method. An alternative to overcome such difficulties is the adoption of the so called non-local constitutive models. In this approach, some internal variables of the constitutive model in a single point are averaged considering its values of the neighbouring points. In this paper, the implicit formulation of the boundar...

Proceedings of the XXXVIII Iberian Latin American Congress on Computational Methods in Engineering, 2017

The failure analysis in structures is extremely important since it allows to evaluate the safety ... more The failure analysis in structures is extremely important since it allows to evaluate the safety degree and the integrity of structural systems. However, despite the increasing use of numerical methods in the study of material failures in the last years, the boundary element method is still little used when compared to domain methods. Thus, in this work it is analyzed the failure mechanics in some classical problems through the continuum strong discontinuity approach. In this way, it is used the implicit formulation of the boundary element method for nonlinear problems to shown the dependence of the step size when the cells with embedded discontinuity are generated only after step convergence or during any iteration, respectively, in the incremental-iterative process. For this purpose, the same problem was analyzed considering these two cases and also different numbers of steps. It was verified that the results are coincident for all numbers of steps considered in the simulations when cells are generated during any iteration, showing step size independence in this case, while the same is not true for the case of cells generated only after convergence, in which a large numbers of steps is required for well accuracy.

Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015

Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015

Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2014

Revista Brasileira de Zootecnia, 2014

The purpose of this study was to evaluate the voluntary intake and digestibility of three sorghum... more The purpose of this study was to evaluate the voluntary intake and digestibility of three sorghum (Sorghum bicolor, L. Moench) hybrid silages in sheep. The hybrids used were H1 -BRS 655 (CMSXS 222 A × CMSXS 235 R), with tannin; H2 -(ATF54 A × CMSXS 235 R), without tannin; and H3 -BRS 610 (CMSXS 232 A × CMSXS 234 R), without tannin. The intake and digestibility of dry matter (DM), gross energy (GE), neutral detergent fiber (NDF), acid detergent fiber (ADF) and crude protein (CP) were measured. Eighteen crossbred sheep weighing 59.4 kg (±8.3) were used in the trial. A completely randomized design with three treatments (hybrids) and six repetitions (sheep) was used. There were no differences in the DM intake or apparent digestibility among the hybrids. Silage of hybrid BRS 610 displayed higher digestibility coefficients for CP, NDF, ADF, and GE compared with the other silages, which did not differ from each other. The neutral detergent fiber, ADF and digestible energy (DE) intakes were similar among the hybrids silages. All of the hybrids resulted in a positive N balance in sheep. The levels of DE were superior in hybrid silage BRS 610 in comparison with the other hybrids. Sorghum hybrid BRS 610 silage exhibited superior nutritional value compared with the other hybrids, which is most likely in part due to the absence of tannins. Sorghum silage made with hybrid BRS 610 (CMSXS 232 A × CMSXS 234 R) presents superior gross energy, crude protein, neutral detergent fiber and acid detergent fiber digestibility coefficients, as well as greater digestible energy levels than BRS 655 (CMSXS 222 A × CMSXS 235 R) and (ATF54 A × CMSXS 235 R).

Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015