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Half Space (half + space)
Selected AbstractsSphere contact fatigue of a coarse-grained Al2O3 ceramicFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 11 2006T. FETT ABSTRACT The opposite sphere test is an appropriate tool to determine crack-growth exponents for fatigue under repeated contact loading. Lifetime measurements for a coarse-grained Al2O3 are reported. To explain the fatigue exponents that strongly deviated from those obtained in cyclic bending tests, a fracture mechanics analysis was carried out. It was aimed at determining the correct stress intensity factor solution for the tests, including limited dimensions of test specimens deviating from the case of a cone crack in a half space. Cone crack development was observed microscopically and the related stress intensity factors were computed for the observed crack shape. For modelling the fatigue behaviour, it is assumed that the fatigue effect is influenced by a reduction of the shielding term of crack growth resistance due to periodical friction between the grain-interlock bridges in coarse-grained alumina. This results in a loss of traction at the junctions, crack tip shielding is reduced, and the effective load at the crack tip is increased. [source] Analytical and numerical solution of the elastodynamic strip load problemINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 1 2008A. Verruijt Abstract Analytical and numerical solutions of the elastodynamic problem of an instantaneous strip load on a half space are presented and compared. The analytical solution is obtained using the De Hoop,Cagniard method, and the numerical solution is obtained using the dynamic module of the finite element package Plaxis. The purpose of the paper is to validate the numerical solution by comparison with a completely analytical solution, and to verify that the main characteristics of the analytical solution are also obtained in the numerical solution. Particular attention is paid to the magnitude, the velocity, and the shape of the Rayleigh wave disturbances. Copyright © 2007 John Wiley & Sons, Ltd. [source] Deformations caused by the movements of shear and tensile faultsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 12 2001Guang Y. Sheu Abstract Earlier solutions of deformations resulting from the movements of shear and tensile faults in a half space (Bull. Seismol. Soc. Amer. 1985; 75:1135, 1992; 82:1018) have been revised in view of cross-anisotropic stress,strain relationships. The dislocation theory (Canad. J. Phys. 1958; 36:192) is reviewed and the displacement field due to a concentrated force in an anisotropic half space is solved analytically for developing the current research. A fault is simulated as a point source of strain nuclei in applying the dislocation theory. Data (Terr. Atmos. Oceanic Sci. 2000; 11(3):591, 631) that were used to study the Chi-Chi earthquake (ML=7.3; 1999/9/21 AM 1:47) are introduced to compare the solution with the isotropic results. Results indicate that the anisotropy of stress,strain relationships does affect the results of predicted deformations. Copyright © 2001 John Wiley & Sons, Ltd. [source] Image reconstruction of buried inhomogeneous dielectric cylinders coated on a conductorINTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 3 2005Chun Jen Lin Abstract The image reconstruction of buried inhomogeneous dielectric cylinders coated on a conductor with known cross-section is investigated. Inhomogeneous dielectric cylinders coated on a conductor is buried in one half space and scatter a group of unrelated waves incident from another half space, where the scattered field is recorded. By proper arrangement of the various unrelated incident fields, the difficulties of ill-posedness and nonlinearity are circumvented, and the permittivity distribution can be reconstructed through simple matrix operations. The algorithm is based on the moment method and the unrelated illumination method. Numerical results show that good reconstruction has been obtained both with and without Gaussian noise in measured data. © 2005 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 15, 172,177, 2005 [source] Thorough analysis of the Oseen system in 2D exterior domainsMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 15 2009Konieczny Abstract We construct Lp -estimates for the inhomogeneous Oseen system studied in a two-dimensional exterior domain , with inhomogeneous slip boundary conditions. The kernel of the paper is a result for the half space ,. Analysis of this model system shows us a parabolic character of the studied problem, resulting as an appearance of the wake region behind the obstacle. Main tools are given by the Fourier analysis to obtain the maximal regularity estimates. The results imply the solvability for the Navier,Stokes system for small velocity at infinity. Copyright © 2009 John Wiley & Sons, Ltd. [source] The Dirichlet problem for non-divergence parabolic equations with discontinuous in time coefficientsMATHEMATISCHE NACHRICHTEN, Issue 9 2009Vladimir Kozlov Abstract We consider the Dirichlet problem for non-divergence parabolic equation with discontinuous in t coefficients in a half space. The main result is weighted coercive estimates of solutions in anisotropic Sobolev spaces. We give an application of this result to linear and quasi-linear parabolic equations in a bounded domain. In particular, if the boundary is of class C1,,, , , [0, 1], then we present a coercive estimate of solutions in weighted anisotropic Sobolev spaces, where the weight is a power of the distance to the boundary (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A study of the four-path model for scattering from an object above a half spaceMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 2 2001Joel T. Johnson Abstract A study of scattering from a dielectric object located above a half space is performed to clarify the accuracy of a "four-path" model which includes single scattering effects only. An iterative method-of-moments solution is used for comparison, and both frequency- and time-domain examples are illustrated to clarify the scattering interactions which occur. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 130,134, 2001. [source] Elastic relaxation of a truncated circular cylinder with uniform dilatational eigenstrain in a half spacePHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2003Frank Glas Abstract We give a fully analytical solution for the displacement and strain fields generated by the coherent elastic relaxation of a type of misfitting inclusions with uniform dilatational eigenstrain lying in a half space, assuming linear isotropic elasticity. The inclusion considered is an infinitely long circular cylinder having an axis parallel to the free surface and truncated by two arbitrarily positioned planes parallel to this surface. These calculations apply in particular to strained semiconductor quantum wires. The calculations are illustrated by examples showing quantitatively that, depending on the depth of the wire under the free surface, the latter may significantly affect the magnitude and the distribution of the various strain components inside the inclusion as well as in the surrounding matrix. [source] Reliability Analysis of Technical Systems/Structures by means of Polyhedral Approximation of the Safe/Unsafe DomainGAMM - MITTEILUNGEN, Issue 2 2007K. Marti Abstract Reliability analysis of technical structures and systems is based on an appropriate (limit) state function separating the safe and unsafe/states in the space of random parameters. Starting with the survival conditions, hence, the state equation and the condition for the admissibility of states, an optimizational representation of the state function can be given in terms of the minimum function of a certainminimization problem. Selecting a certain number of boundary points of the safe/unsafe domain, hence, on the limit state surface, the safe/unsafe domain is approximated by a convex polyhedron defined by the intersection of the half spaces in the parameter space generated by the tangent hyperplanes to the safe/unsafe domain at the selected boundary points on the limit state surface. The resulting approximative probability functions are then defined by means of probabilistic linear constraints in the parameter space, where, after an appropriate transformation, the probability distribution of the parameter vector can be assumed to be normal with zero mean vector and unit covariance matrix. Working with separate linear constraints, approximation formulas for the probability of survival of the structure are obtained immediately. More exact approximations are obtained by considering joint probability constraints, which, in a second approximation step, can be evaluated by using probability inequalities and/or discretization of the underlying probability distribution. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||