Analysis of mechanical properties of the rotational re-entry metastructures skeleton of the aircraft

The deformation wing of aerospaceplane needs to achieve sweep, bending and torsion deformation when performing different flight tasks, and the existing skeleton mechanism may not be able to meet the requirements of large deformation. The rotational re-entrant metastructure proposed in this study provides new ideas and solutions for solving this problem, which is conducive to improving the performance and flexibility of aerospace vehicles.

By establishing a theoretical model of the rotational re-entrant metastructure based on Mohr′s theory, conducting simulation analysis using finite element software, and simultaneously carrying out 3D printing prototype experiments, the theoretical, simulation and experimental results were compared to verify the accuracy of the theoretical model and the simulation model. This research method that combines theory with practice provides a reliable basis for the design and application of metastructures.

The influence of geometric parameters on the elastic parameters of metastructures was analyzed, and it was found that the aspect ratio and structural angles have a significant impact on the Poisson′s ratio mechanical parameters. Based on Mohr′s theorem, the theoretical models of the multi-directional elastic modulus (E_x/E_s, E_y/E_s) and Poisson′s ratio (ν_x-y, ν_x-z, ν_y-x) of metastructure cells are established. Among them, the deviations of the elastic modulus E_x/E_s and E_y/E_s in the experiment and theory were -5.91% and 8.96% respectively, and the deviations of Poisson′s ratios ν_y-x, ν_x-y, and ν_x-z were 8.28%, 2.24%, and 3.83% respectively. The corresponding errors between the simulation and the theory of the experimental samples were -3.74%, -1.57% (elastic modulus) and 5.36%, -3.69%, 0.84% (Poisson′s ratio), respectively. Through parameter research, it was found that the Angle θ₁ in the geometric parameters significantly affects the regulation characteristics of the Poisson′s ratio. υ_x-y shows triple characteristics of negative, zero, and positive Poisson′s ratio, and υ_x-z shows double characteristics of negative and zero Poisson′s ratio. With the increase of the Angle θ₁, the negative Poisson′s ratio effect of υ_x-y in the rotational re-entry metastructures gradually disappears. And the threshold θ₂ required to achieve a positive Poisson′s ratio is reduced. When the aspect ratio increases, at 70°≤θ₂≤80°, the Poisson′s ratio υ_x-y of the rotational re-entry metastructures increases, but it still shows negative Poisson′s ratio characteristics. When 80°≤θ₂≤90°, the Poisson′s ratio υ_x-y of the rotational re-entry metastructures increases, showing positive Poisson′s ratio characteristics. Unlike υ_x-y, with the increase of a₁ and a₂, when 70°≤θ₂≤80°, the Poisson′s ratio υ_x-z of the rotational re-entry metastructures increases, reaching a zero Poisson′s ratio structure when θ₂=80°. When θ₂ > 80°, the Poisson′s ratio υ_x-z decreases and continues to exhibit the characteristics of a negative Poisson′s ratio structure. This research result is conducive to optimizing the design of the rotational reentrant metastructures, enabling it to better meet the actual requirements of the deformable wings of aerospaceplanes, and has important engineering application value.

Aiming at the deformation problem of deformable wing of space vehicle, a rotational re-entry metastructure for deformable wing was proposed. This structure has adjustable Poisson′s ratio characteristics. Theoretical modeling, simulation analysis and parameter research of its mechanical properties are carried out. By taking advantage of the characteristics of the multiple Poisson′s ratio, the metastructures filling unit can be designed separately for the wing filling area, providing a new method with both multi-directional deformation capability and stiffness adjustability for the design of variant wings. The theoretical model and parameterization laws have reference value for the mechanical design of metastructures.