Examinando por Autor "Sánchez Sarmiento, G."
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Ítem Acceso Abierto Analytical determination of heat flow shape factors for composite, prismatic bars of doubly-connected cross section.(North Holland Publishing Co., 1978) Laura, P. A. A.; Sánchez Sarmiento, G.Cylindrical or prismatic configurations are used in many engineering situations (nuclear, mechanical, etc.). Oddly shaped, doubly-connected geometries are required in some applications, and generated in general computer-oriented solutions by the research engineer. The title problem is solved in the present paper using an approximate conformal mapping approach. It is shown that the calculated shape factors are in good agreement with those obtained using a finite element code.Ítem Acceso Abierto Application of conformal mapping to the determination of unsteady temperature distribution in thermally orthotropic plates.(North Holland Publishing Co., 1979) Laura, P. A. A.; Gutiérrez, G. H.; Sánchez Sarmiento, G.Very few papers and reports are available on the solution of heat conduction problems in anisotropic solids. This situation is of particular interest in some nuclear engineering applications (for instance, fuel elements possess, in general, anisotropic characteristics). The present study deals with the solution of an unsteady heat conduction problem in domains of complicated boundary shape, considering a particular case of anisotropy: a thermally orthotropic material. It is shown that the conformal mapping technique coupled with the Ritz method leads to a unified solution of the title problem for an arbitrary orientation for the axes of orthotropy with respect to the directions of the sides of the plates.Ítem Acceso Abierto Approximate, analytical determination of steady state temperature distribution in thermally orthotropic rods.(Aplied science publishers, 1979) Laura, P. A. A.; Gutiérrez, G. H.; Sánchez Sarmiento, G.A conformal mapping-variational approach which allows solution of a type of steady state temperature distribution in bars made of composite materials is developed. The present paper deais with the determ ination of the tem perature field in an orthotropic prismatic bar of arbitrary cross section where the tem perature has a uniform valué on one end and is equal to zero on the other facesÍtem Acceso Abierto Numerical experiments in finite element analysis of thermoelastoplastic behaviour of materials. Further developments of the PLASTEF code.(1980) Basombrío, F. G.; Sánchez Sarmiento, G.In a previous paper the finite element code PLASTEF for the numerical simulation of thermoelastoplastic behaviour of materials was presented in its general outline. This code employs an initial stress incremental procedure for given histories of loads and temperature. It has been formulated for medium sized computers. The present work is an extension of the previous paper to consider additional aspects of the variable temperature case. Non-trivial tests of this type of situation are described. Finally, details are given of some concrete applications to the prediction of thermoelastoplastic collapse of nuclear fuel element cladding.Ítem Acceso Abierto Numerical experiments on the determination of unsteady state temperature distribution in a solid propellant rocket motor.(Elsevier, 1979) Laura, P. A. A.; Sánchez Sarmiento, G.; Olivetto, M. E.The approximate analytical method used in the present study enables the research engineer and applied scientist to find a unified time-dependent solution which is valid regardless the shape of the doubly connected cross section. Admittedly other approximate methods such as the finite difference and the finite elements techniques are more general, but their accuracy is usually tested considering domains of very simple geometry, e.g. the circle or rectangle. The approach followed in this study allows for the finding of analytical solutions in other domains, thus providing an independent check of the accuracy of more general methods.Ítem Acceso Abierto Numerical experiments on the determination of unsteady state temperature distribution in domains of complicated boundary shape.(North Holland Publishing Co., 1978) Laura, P. A. A.; Sánchez Sarmiento, G.; Basombrío, F. G.This paper compares analytical and finite element results for an unsteady heat-conduction problem in simply and doubly connected plates of regular polygonal shape. A numerical solution is obtained by means of the powerful finite element method and the results are shown to agree with an approximate conformal mapping-variational technique previously developed by the first author and coworkers.Ítem Acceso Abierto Numerical experiments on the solution of Helmholtz equation in the case of domains of complicated boundary shape.(North Holland Publishing Co., 1979) Sánchez Sarmiento, G.; Laura, P. A. A.Domains of complicated boundary shape are of great practical importance in several fields of technology and applied science; e.g. solid propellant rocket grains, electromagnetic and acoustic waveguides, and certain elements used in nuclear engineering. The technical literature contains very few comparative studies of analytical and numerical solutions when dealing with such rather com plex geometries. The present study constitutes an effort in that direction.Ítem Acceso Abierto Simulación numérica del comportamiento termoelastoplático de materiales por el metodo de elementos finitos (Código PLASTEF)(EUDEBA, 1978) Basombrío, F. G.; Sánchez Sarmiento, G.Se presenta un código general cuyo propósito es simular el comportamie termoelastico plástico de materiles usando el método de los elementos finitos /3/. Para historias dadas de cargas y temperaturas, permite resolver problemas tecnológicos de variada geometría en tensión plana, deformación plana y simetría de revolución. Admite leyes cualesquiera de endurecimiento por deformación. Descargas o recargas espontáneas son tenidas en cuenta automáticamente en todo punto del material.Ítem Acceso Abierto Some steady and unsteady heat conduction solutions in orthotropic circular cylinders.(North Holland Publishing Co., 1979) Laura, P. A. A.; Sánchez Sarmiento, G.; Gutiérrez, R. H.Simple, approximate solutions are obtained in the case of prescribed axially symmetric boundary conditions. The results are compared in one example with values obtained using a finite element code and good agreement is shown to exist. The problem is of interest in several fields of engineering and applied science, for instance when performing thermal analysis of nuclear fuel elements which in some instances exhibit thermally orthotropic characteristics.Ítem Acceso Abierto Temperature distribution in a composite prismatic rod in the case of heat generation in the circular, cylindrical concentric core.(Elsevier, 1979) Laura, P. A. A.; Sánchez Sarmiento, G.An approximate, analytical approach based on the conformal mapping technique is developed in the present paper. The results are in good agreement with values obtained by means of the finite element method. It is important to point out that configuration such as that shown in Fig. 1 and whose thermal behavior is governed by equations (l)-(3) are of basic importance in several fields of applied sciences: biomedicine, nuclear and chemical engineering, etc.Ítem Acceso Abierto The influence of experimental resolution and bakground upon ion-induced (ve = vi) electron distribution measured behind solid foils.(IOP Publishing, 1979) Chiu, K. C. R.; Meckbach, W.; Sánchez Sarmiento, G.; Mc Gowan, J. W.Some confusion has developed with regard to the correct procedure necessary to compare charge exchange to the continuum (cec) theories and experiment for ion-beam foil collisions where the emitted electrons have velocities v2 = v1 in order to make such a comparison, we emphasize that (a ) the instrumental resolutions in angle and absolute value of velocity must be folded into the theoretical double differential cross section, and (b) that if the emission of (cec) electrons occurs only because of interaction with the outermost atomic layers, those electrons originating from further inside the foil must be subtracted as background. Unfortunately, these considerations were not properly accounted for by Steckelmacher and colleagues as they compared their recent results with theory and published experiments.