J. Phys. I France
Volume 7, Numéro 9, September 1997
Page(s) 1097 - 1111
DOI: 10.1051/jp1:1997111
J. Phys. I France 7 (1997) 1097-1111

Mesh Collapse in Two-Dimensional Elastic Networks under Compression

Wolfgang Wintz1, Ralf Everaers2 and Udo Seifert1

1  Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Kantstrasse 55, 14513 Teltow-Seehof, Germany
2  Institut Charles Sadron, 6, rue Boussingault, 67083 Strasbourg, France

(Received 19 November 1996, revised 18 February 1997, accepted 15 May 1997)

We consider two-dimensional triangular networks of beads connected by Hookean tethers under isotropic compression. We determine both the compression and the shear modulus as a function of temperature and compression within simple approximations and by a Monte Carlo simulation. At low temperature, this network undergoes a collapse transition with increasing compression. In the two phase region, collapsed and non-collapsed triangles coexist. While the compression modulus vanishes in the two phase region, the shear modulus shows only a small anomaly at the transition. With increasing temperature, this transition disappears in our simulation. Anharmonic shear fluctuations invalidate a harmonic analysis in large regions of the phase space. In application to the red blood cell membrane, we obtain good agreement with more microscopic models for the shear modulus. Our results also indicate that strong compression will lead to non-trivial elastic behavior of the cell membrane.

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