3D model of the tetramode sample unit cell. The unit cell exhibits tetragonal symmetry and is placed onto a simple-cubic translation lattice with lattice constant a. The unit cell is constructed from double-cone elements connected by spheres of radius r. The crucial design parameters D and d are the diameter of the double-cone center and the diameter of the connection between double-cones and spheres, respectively. The spheres are chosen as connection hubs for the double-cone elements to obtain a well-defined geometry and to facilitate sample fabrication and the subsequent characterization using optical-image digital cross-correlation analysis and laser Doppler vibrometry. For the constituting material, we choose the parameters of Young's modulus E= 4.19 GPa, Poisson's ratio v= 0.4, and mass density = 1190 kg m−3 for the numerical calculations.
