Seminar from Prof. Yan BEYGELZIMER


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Date | Time
29/10/2014 | 11 h 00 min - 13 h 00 min

Location
Salle Klepaczko

Categories


Prof. Beygelzimer est professeur invité du Labex DAMAS pour une période de deux mois. Il donne un séminaire le 29 novembre, mercredi, à 11H dans le laboratoire LEM3, salle Klepaczko. Son abstract:

A continuum model of plastic deformation of non-compact materials

Prof. Yan Beygelzimer
Donetsk Institute for Physics & Engineering
Ukrainian National Academy of Sciences, Donetsk, Ukraine
yanbeygel@gmail.comhttp://hunch.net/~yan/

The talk presents a model of plastic deformation of non-compact materials. A distinctive feature of the model is that it takes into account the possibility of volume change of materials during deformation under pressure.

A flow function is proposed for porous and powder materials with structurally inhomogeneous structure. Depending on model parameters and the value of porosity, the form of the yield surface corresponding to this loading function can vary from an ellipse (shifted in the negative direction of the hydrostatic stress axis) to a curve similar to an axial cross-section of an egg.

The physical reason for the non-symmetry of the trace with respect to the origin is the partial adaptation to the imposed strain of the structural elements of the material when they are deforming jointly. The constitutive relations based on the proposed loading functions and gradient conditions give a unified framework to study pressure dependent deformation of compact and non-compact  (powder and porous) materials and are able to describe a number of experimentally observed physical effects, the most important are:

  • the emergence, growth, and healing of pores under plastic deformation;
  • the inherent unremovable porosity under full compression of porous and powder materials under constant strain path;
  • the increase of material stability under pressure;
  • the increase in ductility under pressure (in particular, the brittle-ductile transition in hard to deform materials).