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The work is devoted to the numerical analysis of the uniaxial loading of a sample of mechanical metamaterial. The structure of the mechanical metamaterial is constructed of a ring and four ligaments, making up a tetrachiral structure. The peculiarity of such a structure consists of the twist of the sample under the force load. Numerical simulation of uniaxial loading of the samples allowed us to obtain the results of their mechanical response and to analyze the influence of the number of cells in the rod on its mechanical behavior. The results showed that the additivity principle for twist is invalid, which means that predicting the behavior of the rod as the number of unit cells in it increases is possible with some inaccuracy. The displacements of the vertices of the square sections and the ends of the rod depend linearly on its length measured in the number of unit cells. A similar dependence will be maintained with a further increase in the length of the metamaterial rod. [ABSTRACT FROM AUTHOR]

The creation of functional materials is a promising direction for engineering development. Functional materials include metamaterials among others. Metamaterials achieve the required properties using a rationally designed structure. Tetrachiral structures differ from the others in that they can twist under uniaxial loading. This paper solves the quasi-static problem of uniaxial loading within the framework of linear elasticity theory using the finite element method. It is investigated how the support reaction changes when a second ring is added into the chiral structure. The dependence obtained suggests that by adding a complementary ring and increasing its size more forces have to be applied to deform the metamaterial. It is shown how the size of the secondary ring affects Young's modulus. [ABSTRACT FROM AUTHOR]

The simulation results of the interactions between a solid impactor and a barrier with various grid configurations are considered. As a result of numerical simulation, we have obtained the change in the velocity of a projectile modeled by SPH particles. To study the impactor behavior after interacting with a grid barrier, various grid configurations are chosen: free laying of mutually perpendicular wires without weaving, the imposition of mutually perpendicular sinusoidal curved wires with the coincidence of maxima and minima, and wicker. The influence of grid wickering in this model proves to be insignificant, and an interesting effect is observed: for a tougher version with a wicker barrier, the destruction of the projectile is greater, but the deceleration is less than a protective screen of equal weight from superimposed sinusoidal wires. [ABSTRACT FROM AUTHOR]

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]

The paper presents the results on the investigation of the accumulation of plastic strain and damage in the sample of sheet metal from lightweight structural aluminum alloy during the process of severe plastic deformation, using numerical simulation. It is proposed to use the dynamic version of the groove pressing to realize the severe plastic deformation of flat samples. A groove die with a groove of trapezoidal form is considered here. The process of dynamic groove pressing was numerically investigated in a two-dimensional formulation under plane strain condition. The maximum value of the effective plastic strain develops in the stretching area of the material and reaches a value of 0.75. In the zone of interaction between the groove of the die and the sample, the highest values of the damage parameter are achieved. [ABSTRACT FROM AUTHOR]