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Erasmo Carrera - One of the best experts on this subject based on the ideXlab platform.
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on the use of transverse shear stress homogeneous and non homogeneous conditions in third order orthotropic plate theory
Composite Structures, 2007Co-Authors: Erasmo CarreraAbstract:Abstract This paper discusses the influence of non-homogeneous transverse shear stresses conditions on the accuracy of plate theories formulated in terms of displacement variables. The case of a third-order plate theories is considered and the attention has been focused on cylindrical bending problems. The following three models are developed and compared: (1) the ‘original’ third model with five displacement variables; (2) the ‘reduced’ third-order model with three displacement variables obtained by imposing ‘homogeneous’ stress conditions with correspondence to the plate top-surface; (3) the modification of case 2 which considers ‘non-homogeneous’ stress conditions. Variationally consistent governing equations have been derived by employing the principle of virtual displacement in the linear-elastic, static case. Closed form solutions results have been obtained for both stresses and displacements in the case of harmonic loadings and simply supported boundary conditions. The following main conclusions have been reached by the conducted numerical investigation: The use of non-homogeneous boundary conditions lead to a general improvement with respect to model 2 results. The ‘original’ model leads in general to better response evaluation than the other two models; an exception is made for the transverse shear stresses calculated by Hooke Law for which case model 3 leads to the most accurate results.
E. Salusti - One of the best experts on this subject based on the ideXlab platform.
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On the Theory of Solitons of Fluid Pressure and Solute Density in Geologic Porous Media, with Applications to Shale, Clay and Sandstone
Pure and Applied Geophysics, 2017Co-Authors: A. Caserta, R. Kanivetsky, E. SalustiAbstract:We here analyze a new model of transients of pore pressure p and solute density ρ in geologic porous media. This model is rooted in the nonlinear wave theory, its focus is on advection and effect of large pressure jumps on strain. It takes into account nonlinear and also time-dependent versions of the Hooke Law about stress, rate and strain. The model solutions strictly relate p and ρ evolving under the effect of a strong external stress. As a result, the presence of quick and sharp transients in low permeability rocks is unveiled, i.e., the nonlinear “Burgers solitons”. We, therefore, show that the actual transport process in porous rocks for large signals is not only the linear diffusion, but also a solitons presence could control the process. A test of a presence of solitons is applied to Pierre shale, Bearpaw shale, Boom clay and Oznam-Mugu silt and clay. An application about the presence of solitons for nuclear waste disposal and salt water intrusions is also discussed. Finally, in a kind of “theoretical experiment” we show that solitons could also be present in higher permeability rocks (Jordan and St. Peter sandstones), thus supporting the idea of a possible occurrence of osmosis also in sandstones.
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On the theory of solitons of fluid pressure and solute density in geologic porous media, with applications to shale, clay and sandstone
Pure and Applied Geophysics, 2017Co-Authors: A. Caserta, R. Kanivetsky, E. SalustiAbstract:In this paper we propose the application of a new model of transients of pore pressure p and solute density \r{ho} in geologic porous media. This model is rooted in the non-linear waves theory, the focus of which is advection and effect of large pressure jumps on strain (due to large p in a non-linear version of the Hooke Law). It strictly relates p and \r{ho} evolving under the effect of a strong external stress. As a result, the presence of quick and sharp transients in low permeability rocks is unveiled, i.e. the non-linear Burgers solitons. We therefore propose that the actual transport process in porous rocks for large signals is not the linear diffusion, but could be governed by solitons. A test of an eventual presence of solitons in a rock is here proposed, and then applied to Pierre Shale, Bearpaw Shale, Boom Clay and Oznam-Mugu silt and clay. A quick analysis showing the presence of solitons for nuclear waste disposal and salty water intrusions is also analyzed. Finally, in a kind of "theoretical experiment" we show that solitons could also be present in Jordan and St. Peter sandstones, thus suggesting the occurrence of osmosis in these rocks.
A A Zheltukhin - One of the best experts on this subject based on the ideXlab platform.
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generalized Hooke Law for relativistic membranes and p branes
arXiv: High Energy Physics - Theory, 2012Co-Authors: A A ZheltukhinAbstract:The character of elastic forces of relativistic membranes and $p$-branes encoded in their nonlinear equations is studied. The toroidal brane equations are reduced to the classical equations of anharmonic elastic media described by monomial potentials. Integrability of the equations is discussed and some of their exact solutions are constructed.
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section a quantum field theory generalized Hooke Law for relativistic membranes and p branes
2012Co-Authors: A A ZheltukhinAbstract:A.I. Akhiezer paid much attention to search for effects connected with elastic wave propagation in condensed matter physics [1]. Relativistic membranes (p=2) and p-branes in higher dimensional space-time are fundamental objects of string theory [2], and their macroscopic physics is also controlled by effective elastic forces of fluxes of elementary particle fields, like QCD tubes in string theory. However, quantization of branes is blocked up by nonlinearity of their equations (see e.g. [3-15] and many others). The classical and quantum problems of the brane physics deserve great attention and stimulate investigation of elastic forces associated with relativistic branes. Here we search the physics of closed pbranes (with p = 2, 3, ...) evolving in D = (2p+ 1)dimensional Minkowski space, and find their exact solutions. The brane shape is chosen to be invariant under the global symmetry O(2)×O(2)×...×O(2). The p-brane equations are reduced to nonlinear ones of an elastic anharmonic medium with a symmetric stress tensor generated by the interaction Hamiltonian proportional to a monomial potential of the degree 2p. Exact solvability of degenerate p-brane shaped as ptorus with equal radii, is established. The found solutions are presented by (hyper)elliptic functions that describe p-branes contracting during the time defined by their energy density and the dimension p.
A. Caserta - One of the best experts on this subject based on the ideXlab platform.
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On the Theory of Solitons of Fluid Pressure and Solute Density in Geologic Porous Media, with Applications to Shale, Clay and Sandstone
Pure and Applied Geophysics, 2017Co-Authors: A. Caserta, R. Kanivetsky, E. SalustiAbstract:We here analyze a new model of transients of pore pressure p and solute density ρ in geologic porous media. This model is rooted in the nonlinear wave theory, its focus is on advection and effect of large pressure jumps on strain. It takes into account nonlinear and also time-dependent versions of the Hooke Law about stress, rate and strain. The model solutions strictly relate p and ρ evolving under the effect of a strong external stress. As a result, the presence of quick and sharp transients in low permeability rocks is unveiled, i.e., the nonlinear “Burgers solitons”. We, therefore, show that the actual transport process in porous rocks for large signals is not only the linear diffusion, but also a solitons presence could control the process. A test of a presence of solitons is applied to Pierre shale, Bearpaw shale, Boom clay and Oznam-Mugu silt and clay. An application about the presence of solitons for nuclear waste disposal and salt water intrusions is also discussed. Finally, in a kind of “theoretical experiment” we show that solitons could also be present in higher permeability rocks (Jordan and St. Peter sandstones), thus supporting the idea of a possible occurrence of osmosis also in sandstones.
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On the theory of solitons of fluid pressure and solute density in geologic porous media, with applications to shale, clay and sandstone
Pure and Applied Geophysics, 2017Co-Authors: A. Caserta, R. Kanivetsky, E. SalustiAbstract:In this paper we propose the application of a new model of transients of pore pressure p and solute density \r{ho} in geologic porous media. This model is rooted in the non-linear waves theory, the focus of which is advection and effect of large pressure jumps on strain (due to large p in a non-linear version of the Hooke Law). It strictly relates p and \r{ho} evolving under the effect of a strong external stress. As a result, the presence of quick and sharp transients in low permeability rocks is unveiled, i.e. the non-linear Burgers solitons. We therefore propose that the actual transport process in porous rocks for large signals is not the linear diffusion, but could be governed by solitons. A test of an eventual presence of solitons in a rock is here proposed, and then applied to Pierre Shale, Bearpaw Shale, Boom Clay and Oznam-Mugu silt and clay. A quick analysis showing the presence of solitons for nuclear waste disposal and salty water intrusions is also analyzed. Finally, in a kind of "theoretical experiment" we show that solitons could also be present in Jordan and St. Peter sandstones, thus suggesting the occurrence of osmosis in these rocks.
Marc Leonetti - One of the best experts on this subject based on the ideXlab platform.
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stretching of capsules in an elongation flow a route to constitutive Law
Journal of Fluid Mechanics, 2015Co-Authors: Clément De Loubens, Gwenn Boedec, Julien Deschamps, Marc LeonettiAbstract:Soft bio-microcapsules are drops bounded by a thin elastic shell made of cross-linked proteins. Their shapes and their dynamics in flow depend on their membrane constitutive Law characterized by shearing and area-dilatation resistance. The deformations of such capsules are investigated experimentally in planar elongation flows and compared with numerical simulations for three bidimensional models: Skalak, neo-Hookean and generalized Hooke. An original cross-flow microfluidic set-up allows the visualization of the deformed shape in the two perpendicular main fields of view. Whatever the elongation rate, the three semi-axis lengths of the ellipsoid fitting the experimental shape are measured up to 180 % of stretching of the largest axis. The geometrical analysis in the two views is sufficient to determine the constitutive Law and the Poisson ratio of the membrane without a preliminary knowledge of the shear elastic modulus $G_{s}$ . We conclude that the membrane of human serum albumin capsules obeys the generalized Hooke Law with a Poisson ratio of 0.4. The shear elastic modulus is then determined by the combination of numerical and experimental variations of the Taylor parameter with the capillary number.