Auxetic metamaterials have received wide attention due to their idiosyncratic physical properties. In this paper, experiments and simulations were performed to study the mechanical and acoustic properties of a 3D anti-chiral auxetic metamaterial subjected to quasi-static loading. The results shows that Poisson's ratio of the designed metamaterial can be changed from −0.45 to 0.35 with different cell parameters. Acoustic tests show that the designed metamaterial provides an ultra-wide phononic bandgap and exhibits outstanding wave attenuation properties. By applying rational tensile/compression force, the bandgap is widened/narrowed, which indicates the tunability of the bandgap through deformation. Moreover, the bandgap tuning is through all high symmetry points in the Brillouin zone due to the iso-auxeticity of the metamaterial. This study provides a possible way for controlling the bandgap with the deformable metamaterial.

In this paper, the anisotropic mechanical properties of rolled AZ31 magnesium alloys are investigated using nanoindentation tests at room temperature. Nanoindentation was carried out at four angles, including the rolling direction (0°), diagonal direction (45°), transverse direction (90°), and vertical direction (ND). Experimental results show that hardness increases as the rolling angle increases from 0° to 90° and is lowest in the ND direction. The hardness independent of the effect of indentation depth is obtained by analyzing the indentation size effect and then converting hardness values into yield strengths. A new criterion is proposed on the basis of the Hill48 yield criterion. The data obtained through the above experiments are used to determine the parameters in the new criterion. Finally, a solution to the challenge of modeling a function that accurately describes the anisotropic yielding behavior of AZ31 magnesium alloys is proposed using the nanoindentation technique to solve the requirements of specimen size and experimental methods of the macro test.