Second gradient vs. surface energy in the Asaro-Grinfeld instability

This paper study an instability phenomenon that arise in epitaxial growth of single crystals with lattice mismatch. We compare a classical approach, based on the competition between the bulk and surface energies, with a non-standard one when the surface term is replaced by a term including the second gradient of the displacement field. We evidence how secontl order gradients may stabilize lower modes of corrugated boundaries, via an intrisic length scale

Abeyaratne, R.: Knowles, J. K.: Evolution of Phase Transitions - A Continuum Theory; Bertram, A.: Elasticity and Plasticity of Large Deformations - An Introduction; Papula, L.: Mathematik für Ingenieure und Naturwissenschaftler, Band 1

Abeyaratne, R.:Knowles, J. K.: Evolution of Phase Transitions - A Continuum TheoryCambridge, University Press, 2006, USD 85,00ISBN-13: 9780521661478, ISBN-10: 0521661471 Bertram, A.:Elasticity and Plasticity of Large Deformations - An IntroductionSpringer, Berlin, 1. Auflage (2005), 326 Seiten, € 74,85ISBN-10: 35402403330, ISBN-13: 978-3540240334 Mao-Hong Yu:Generalized PlasticitySpringer 2006, 468 S., 315 Abb., 22 Tab.ISBN 3-540-25127-8, € 129,95 Papula, L.:Mathematik für Ingenieure und Naturwissenschaftler, Band 1Vieweg Verlag, Wiesbaden, 2007, 11., verbesserte und erweiterte Auflage, 683 Seiten, 493 Abb., € 29,80ISBN 978-3-8348-0224-

Constitutive parameters identification for elastoplastic materials in finite deformation

In this contribution, inverse identification methods of constitutive laws for elastoplastic behaviour are compared. These proposed inverse algorithms are composed on a finite element calculation combined with an optimisation procedure. They are applied to identify material anisotropic coefficients using a set up of easy performed tests. The used experimental data are the plane tensile test and the off axes tensile tests. The data correspond to various virtual elastoplastic orthotropic materials where quadratic or non quadratic criteria with or without associated normality are considered. Three identification methods are compared to find anisotropic parameters. Particular attention is devoted to the impact of the hypothesis on identified parameters

Rolling bearing applications: some trends in materials and heat treatments

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