A compact 3D bandgap multi-material metamaterial design for vibration testing

The use of metamaterials is an established approach in the field of vibration isolation, leveraging their exceptional tunability over a vast range of frequencies. A key challenge in designing lattice structures is the trade-off between geometrical compactness and wideness of the bandgap, i.e. the frequency range in which wave propagation is not allowed. A possible solution to reduce the size of the structure while maintaining or improving its vibrational performances, is to incorporate different materials in the metamaterial design. In this paper, we present a compact metamaterial, whose design is driven by a multi-material approach, that exhibits extraordinary properties in terms of wide frequency bandgap and lower frequency threshold. The vibrational performance of the proposed metamaterial is validated both numerically and experimentally for a unit cell with a side length of 3 cm. The results show a bandgap opening frequency of 1257 Hz and a low pass filter behavior in the range 1.2...