### Article

## Auxetic Properties of Hiral Hexagonal Cosserat Lattices Composed of Finite-Sized Particles

This article is devoted to the study of auxetic properties of Cosserat hexagonal

lattices composed of finite-sized particles with complex connections. The

description of complex connections is given; their mathematical model is

elaborated and the properties are studied. The introduction of complex connections

enables one varying their structure and component parameters. Due to

that there arise possibilities for both simulation of nonchiral lattices with symmetrical

bonds and with a chiral microstructure and construction of lattices with

desired properties. The discrete and micropolar equations of the lattice are

obtained. As a result, the macroparameters are expressed in terms of the lattice

microparameters. The dependence of the Poisson’s ratio on the lattice microparameters

is obtained. It allows finding and analyzing parameters, for which the

lattice possesses auxetic properties. The importance of rotational degrees of

freedom of particles and chirality for the appearance of auxetic properties is

shown. For verification, the results of the calculation of the Poisson’s ratio

obtained on the basis of theoretically obtained relations are compared with the

results of numerical simulation of the stretching of the lattice.