Encontrados 23 documentos, a visualizar página 1 de 3
Mechanical properties of sintered La9.33Si2Ge4O26 oxyapatite materials for SOFC...
Santos, Miguel; Alves, Cátia; Oliveira, F. A. Costa; Marcelo, Teresa; Mascarenhas, João; Fernandes, J.V.; Trindade, B.Mechanical properties of La9.33Si2Ge4O26 prepared by mechanical alloying and subsequent sintering at 1300–1400 °C for 1 h were evaluated. Hardness and Young's modulus values in the range 7.3–9.6 GPa and 106–135 GPa, respectively, were obtained from nanohardness tests. The fracture toughness values derived from the Palmqvist method varied between 3.5 and 3.9 MPa m1/2 from classical microindentation test with an ...
Comparison between Berkovich, Vickers and conical indentation tests: A three-di...
Sakharova, N. A.; Fernandes, J. V.; Antunes, J. M.; Oliveira, M. C.http://www.sciencedirect.com/science/article/B6VJS-4TX33SP-1/2/d6a73a3da766b19e2ec9da73a5f5d209
Strain path and work-hardening behavior of brass
Sakharova, N. A.; Fernandes, J. V.; Vieira, M. F.http://www.sciencedirect.com/science/article/B6TXD-4VCH6XN-2/2/f2fdcdb8e9296ed402996e926d4803b4
Material parameters identification: Gradient-based, genetic and hybrid optimiza...
Chaparro, B. M.; Thuillier, S.; Menezes, L. F.; Manach, P. Y.; Fernandes, J. V.This paper presents two procedures for the identification of material parameters, a genetic algorithm and a gradient-based algorithm. These algorithms enable both the yield criterion and the work hardening parameters to be identified. A hybrid algorithm is also used, which is a combination of the former two, in such a way that the result of the genetic algorithm is considered as the initial values for the gradi...
Influence of Vickers tip imperfection on depth sensing indentation tests
Antunes, J. M.; Menezes, L. F.; Fernandes, J. V.In the last decade, the development of depth sensing indentation equipment has permitted two of the most conventional mechanical properties of materials to be easily determined: hardness and Young's modulus. Some care is needed to accurate results from the experimental determination of the aforementioned mechanical properties. In this study, numerical simulations were performed on two well-known materials (Bk7 ...
A new approach for reverse analyses in depth-sensing indentation using numerica...
Antunes, J. M.; Fernandes, J. V.; Menezes, L. F.; Chaparro, B. M.This paper seeks to present a new approach to reverse analysis in depth-sensing indentation which makes use of numerical simulation. This methodology allows the results of experimental hardness tests acquired with single indenter geometry to be used to determine the plastic properties of materials. Forward and reverse analyses of high deformation three-dimensional numerical simulations of Vickers indentation te...
Strain path change effect on dislocation microstructure of multicrystalline cop...
Sakharova, N. A.; Fernandes, J. V.In this study, coarse-grained copper sheets were subjected to tension-rolling and rolling-tension strain path sequences. In both cases, two different types of strain path change were studied: the tensile and rolling directions were parallel and normal to each other. TEM observations of deformed samples showed the typical dislocation structures for the prestraining paths in tension and rolling. Special microband...
Three-dimensional numerical simulation of Vickers indentation tests
Antunes, J. M.; Menezes, L. F.; Fernandes, J. V.The development of depth sensing indentation equipment has allowed easy and reliable determination of two of the most popular measured mechanical properties of materials: the hardness and the Young's modulus. However, some difficulties emerge in the experimental procedure to calculate accurate values of these properties. This is related to, for example, the tip geometrical imperfections of the diamond pyramidal...
Numerical study of the plastic behaviour in tension of welds in high strength s...
Rodrigues, D. M.; Menezes, L. F.; Loureiro, A.; Fernandes, J. V.The influence of the mismatch between material properties and constraint on the plastic deformation behaviour of the heat affected zone of welds in high strength steels is investigated in this study, using finite element simulations. An elastoplastic implicit three-dimensional finite element code (EPIM3D) was used in the analysis. The paper presents the mechanical model of the code and the methodology used for ...
On the evaluation of the ductility of thin films
Antunes, J. M.; Menezes, L. F.; Vieira, M. F.; Fernandes, J. V.; Trindade, B.; Ramos, A. S.; Vieira, M. T.A new tensile test procedure has been developed to evaluate the ductility of thin films deposited on a substrate. The tensile sample has a continuously variable cross-sectional area, resulting in a continuous strain gradient along the sample after deformation. The films present cracks where the strain imposed exceeds their ductility. The strain attained at the boundary of the region where cracks appear characte...
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