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The paper deals with the problem of deforming a mechanical metamaterial. The metamaterial is constructed from chiral elements comprising rings and ribs. The behavior of the bulk metamaterial sample during compression was studied numerically in the framework of linear elasticity theory. Due to the chiral structure, the metamaterial sample exhibits unusual effects. One of them relates to nonlinear transformations, namely a twist. It was found that the deformations are distributed irregularly over the material. During the compression of the metamaterial sample, the rings undergo a torque, and the ribs begin to bend. All the ribs of the metamaterial sample undergo similar bending. Additionally, there are areas affected by two codirectional bends with different signs. Strain localization and the corresponding stress concentrations are of great importance from the strength analysis point of view. As for Young's modulus, it is significantly (by 100 times) less for the metamaterial sample than for the base material. It is justifiable since the ratio of the volume of a base solid to the volume of the metamaterial is quite large. When constructed the tetrachiral structure, the porosity value is 98%. [ABSTRACT FROM AUTHOR]

The paper deals with a 2D metamaterial constructed from chiral elements comprising rings and ligaments (ribs). The behavior of the metamaterial during tension was studied by numerical modeling. The shear deformation appears within the tetrachiral honeycomb under uniaxial loading. It is found that coupling exists between the elongation and inclination of the sample with tetrachiral honeycomb structure and this causes some ambiguity when calculating the effective Poisson's ratio. The coupling effect depends on both the honeycomb's deformation and the geometric parameters of the cell structure. This special coupling effect of tetrachiral honeycombs provides a new idea for designing new metamaterials. An analytical expression for this effective Poisson's ratio is derived. In the process of uniaxial loading, the reason for the elongation of the specimen was found. [ABSTRACT FROM AUTHOR]

The paper investigates the deformation behavior of a mechanical metamaterial. The metamaterial is made up of tetrachiral elements. An analytical solution is obtained for the deformation behavior of a unit cell of the metamaterial depending on its parameters. The results of the analytical solution were used for numerical modeling. The computer FEM model was built using beam elements. The numerical solution of the mechanical loading of the metamaterial was performed in the static case of the linear theory of elasticity. In the course of numerical simulation of the uniaxial loading of the mechanical metamaterial, it was found that the specimen inclines when elongated. The difference in inclination angles between the right and left sides of the specimen is probably related to the rotation of the ring in the tetrachiral structure. [ABSTRACT FROM AUTHOR]