CATASTROPHIC MICRODEFORMATIONS IN CRYSTALLINE LATTICE.
STRUCTURE STABILITY AND MODIFICATIONS.
Institute of Problems of Mechanical Engineering,
Russian Academy of Sciences, Saint-Petersburg, 199178.
Essentially nonlinear theory of two dimensional lattice subjected to
intensive shear is presented. Two branches of deformations
(acoustic and pseudo optical) are considered. The deformation energy
is shown to consist of periodic and gradient terms. The equilibrium
equation in the sine-Helmholtz form is exactly solved. It demonstrates
some effects of bifurcations. he first, when homogeneous macrodeformation
is transformed to nonhomogeneous one and some superstructure with great
periods and new translation order is formed. The second bifurcation divides
two deformed states-elastic and elastoplastic one when the nearest
atomic order is altered and new modification of crystalline lattice is formed.
Some criteria of local and global structure stability are established.
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