The Experts below are selected from a list of 312330 Experts worldwide ranked by ideXlab platform
David Izabel - One of the best experts on this subject based on the ideXlab platform.
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Taking into account the rigidity of space-time in general relativity - Understanding by a simple analogy based on the concepts of the Strength of Materials
2017Co-Authors: David IzabelAbstract:The discoveries of gravitational waves linked to binary black holes coalescence have multiplied since 11 February2016. The formation of a resulting black hole from this cataclysmic event, concentrating in the final stage in a very small radius a colossal mass (50 solar masses and more), is sufficiently energetic to deform the space-time which then propagates without any attenuation during Billions of years, the associated gravitational waves. These were predicted by Einstein in his theory of general relativity a century ago. Their measurements, which are characterized by an infinitesimal DL / L deformation (10-21 , or 10-18 at the kilometer size of the interferometers), corresponds to the billionth of the size of an atom, today. The smallness of its deformations is the character trait of an extraordinarily great rigidity of space-time. We will show in this paper that the constant of proportionality κ between the curvature tensor Gμv and the stress energy tensor Tμv is a characterization of this very high rigidity. To do this we will make an analogy with the Strength of Materials via the theory of the beams to show it.
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Can we understand the concepts of the General Relativity and of the Quantum Mechanics based on the principles of the Strength of Materials? Reflections and proposals
2017Co-Authors: David IzabelAbstract:The quantum mechanics, in the infinitesimal world, is the reign of the quantification of energies, and of the probability of presence of particles with the famous wave function ψ associated at the Schrodinger equation. The General relativity, is for it, reserved at the infinitely large world where the mater, the energy density influence the curvature of the space time at 4 dimensions and reciprocally. Finally, the Strength of Materials is the mechanic of objects at the human scale (beams, columns, plates, shells) used for the design of structures, without common measures with this two pillars of the of the physics cited earlier. We are going to show in first part of this paper that the results of the quantum mechanics (quantification of energy, shape of the wave function) are similar at the eigen frequencies and eigen modes of a beam. In second part, we will show on simples cases, that the concepts of curvature linked with energy density present in general relativity are equally at the bases of the fundamental equations of the elasticity and of the Strength of material. We will demonstrate finally that the stress energy tensor written for small speeds non relativistic is an extension in 4 dimensions of stress tensor of the elasticity theory.
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Can we estimate the Young's modulus of the space-time from simple analogies based on the concepts of the Strength of Materials? Reflection and proposals
2017Co-Authors: David IzabelAbstract:Einstein has shown that the matter curves the space-time. In its model, the space-time is a mathematical conceptualization unifying the space and the time that accounts for measured physical phenomena (delay of the perihelion of Mercury, deviation, curvature of light by a large mass, relativity of length and time, propagation of gravitational waves, caused in particular by coalescence of black holes, which materialize by infinitesimal deformations DL / L of space-time (10-21)), etc. The question that then comes to mind is whether the mathematical conceptualization of space-time has a physical reality? In this case, what is the material of the fabric of the space-time that undulates or bends under gigantic masses in motion? Where, from a mechanical point of view, can we find an equivalent Young's modulus E to the fabric of the space-time? A first clue is the Casimir's force, which tells us that the vacuum of space is not empty ... From recent publications on the subject and simple analogies based on the Strength of Materials, we will show that if the E-module of space-time exists, it seems incommensurably large whatever the approach considered (elastic plates in 2 dimensions, plates analyzed by a tensor calculation in 4 dimensions, strings, Casimir force). In any case, only a measure of the latter would make it possible to decide definitively.
Vaclav Vitek - One of the best experts on this subject based on the ideXlab platform.
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The role of ab initio electronic structure calculations in studies of the Strength of Materials
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2004Co-Authors: Mojmír Šob, Martin Friák, Dominik Legut, Jaroslav Fiala, Vaclav VitekAbstract:Abstract In this paper we give an account of applications of quantum-mechanical (first-principles) electronic structure calculations to the problem of theoretical tensile Strength in metals and intermetallics. First, we review previous as well as ongoing research on this subject. We then describe briefly the electronic structure calculational methods and simulation of the tensile test. This approach is then illustrated by calculations of theoretical tensile Strength in iron and in the intermetallic compound Ni 3 Al. The anisotropy of calculated tensile Strength is explained in terms of higher-symmetry structures encountered along the deformation paths studied. The table summarizing values of theoretical tensile Strengths calculated up to now is presented and the role of ab initio electronic structure calculations in contemporary studies of the Strength of material is discussed.
L. S. Globa - One of the best experts on this subject based on the ideXlab platform.
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Development of a model for the internet portal "Strength of Materials"
Materiali in Tehnologije, 2012Co-Authors: L. S. Globa, R. L. Novogrudska, Ilija MamuzićAbstract:We present an approach to the development of a specialized-knowledge Internet portal for work with large quantities of information and computational resources in the field of Strength of Materials. The ontology-based portal provides an information basis for the design of alloys represented by the chosen fields of science, which may be difficult for formalizing, and it allows the use of web services for the realization of engineering tasks with the Internet and material-science knowledge that is accumulated in the databases.
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Informational and computational resourses of Internet-portal «Strength of Materials» integration
2011 21st International Crimean Conference "Microwave & Telecommunication Technology", 2011Co-Authors: L. S. Globa, R. L. NovogrudskaAbstract:The present paper describes an approach to the internet portal in the Strength of Materials designing. The process of analysis and modeling of business processes of the portal is described.
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Integration of informational and computational recourses on the portal “Strength of Materials”
2011 11th International Conference The Experience of Designing and Application of CAD Systems in Microelectronics (CADSM), 2011Co-Authors: L. S. Globa, Rina NovogrudskayaAbstract:The report presents the approach to solving the informational and computational recourses integration into Internet portal of different direction. The possibility of designing the Internet portal in the field of Strength of Materials for providing meaningful accesses to knowledge and data is described. The conceptual model of such portal was formed based on the ontology model.
Narita Toshio - One of the best experts on this subject based on the ideXlab platform.
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Fracture Behavior of Oxide Scales and Influence of Oxide Scales on the Strength of Materials
Transactions of Materials Processing, 2004Co-Authors: Narita ToshioAbstract:An Fe-25Cr steel was oxidized in Ar atmosphere at 973K with and without applying external stress of 30∼35 MPa. A 0.1 thick scales formed during pre-treatment in Ar atmosphere. Initiation of cracking on the oxide scales took place at grain boundaries during the end of second creep stage, in which cracks were found nearly perpendicular to the tensile directions. On the contrary, a scale developed in -0.1% displaced a poor adherence on the metal substrate. In this sample, a fast grown of scales was observed during creep deformation, and the Strength of Materials was much lower than in Ar. The creep strain rate of and was determined in Ar and in -0.1% under 30MPa, respectively.
Mojmír Šob - One of the best experts on this subject based on the ideXlab platform.
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The role of ab initio electronic structure calculations in studies of the Strength of Materials
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2004Co-Authors: Mojmír Šob, Martin Friák, Dominik Legut, Jaroslav Fiala, Vaclav VitekAbstract:Abstract In this paper we give an account of applications of quantum-mechanical (first-principles) electronic structure calculations to the problem of theoretical tensile Strength in metals and intermetallics. First, we review previous as well as ongoing research on this subject. We then describe briefly the electronic structure calculational methods and simulation of the tensile test. This approach is then illustrated by calculations of theoretical tensile Strength in iron and in the intermetallic compound Ni 3 Al. The anisotropy of calculated tensile Strength is explained in terms of higher-symmetry structures encountered along the deformation paths studied. The table summarizing values of theoretical tensile Strengths calculated up to now is presented and the role of ab initio electronic structure calculations in contemporary studies of the Strength of material is discussed.
