998 resultados para Screw theory
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A constitutive model, based on an (n + 1)-phase mixture of the Mori-Tanaka average theory, has been developed for stress-induced martensitic transformation and reorientation in single crystalline shape memory alloys. Volume fractions of different martensite lattice correspondence variants are chosen as internal variables to describe microstructural evolution. Macroscopic Gibbs free energy for the phase transformation is derived with thermodynamics principles and the ensemble average method of micro-mechanics. The critical condition and the evolution equation are proposed for both the phase transition and reorientation. This model can also simulate interior hysteresis loops during loading/unloading by switching the critical driving forces when an opposite transition takes place.
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Resumen: El presente trabajo busca clarificar (en polémica con el abordaje de Stephen Priest) el auténtico sentido del “subjetivismo” merleaupontyano con respecto al tiempo, según el cual solo existe tiempo como correlato de una subjetividad situada en él. En un marco más general, reponer esta tesis merleaupontyana permite colocar las reflexiones del fenomenólogo francés en diálogo con la tradición analítica sobre el tiempo (centrada en el debate entre las teorías “A” y “B”), y, en particular, en continuidad temática con el abordaje de la “paradoja de McTaggart” por parte de Michael Dummett
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A previously published refined shear deformation theory is used to analyse free vibration of laminated shells. The theory includes the assumption that the transverse shear strains across any two layers are linearly dependent on each other. The theory has the same dependent variables as first-order shear deformation theory, hut the set of governing differential equations is of twelfth order. No shear correction factors are required. Free vibration of symmetric cross-ply laminated cylindrical shells, symmetric and antisymmetric cross-ply cylindrical panels is calculated. The numerical results are in good agreement with those from three-dimensional elasticity theory.
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Texto em português e inglês.
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An optimal theory on how database analysis to capture the flow structures has been developed in this paper, which include the POD method as its special case. By means of the remainder minimization method in the Sobolev space, for more general optimal conditions the new theory has the potential to overcome an inherent limitation of the POD method, i.e., it cannot be used to the situations in which the optimal condition is other than the inner product global one. As an example, using the new theory, the database of a two-dimensional flow over a backward-facing step is analyzed in detail, with velocity and vorticity bases.