Tailored Mechanical Metamaterials with Programmable Quasi-Zero-Stiffness Features for Full-Band Vibration Isolation

Quasi-zero-stiffness (QZS) isolators of high-static-low-dynamic stiffness play an important role in ultra-low frequency vibration mitigation. While the current designs of QZS mainly exploit the combination of negative-stiffness corrector and positive-stiffness element, and only have a single QZS working range, here a class of tailored mechanical metamaterials with programmable QZS features is proposed. These programmed structures contain curved beams with geometries that are specifically designed to enable the prescribed QZS characteristics. When these metamaterials are compressed, the curved beams reach the prescribed QZS working range in sequence, thus enabling tailored stair-stepping force-displacement curves with multiple QZS working ranges. Compression tests demonstrate that a vast design space is achieved to program the QZS features of the metamaterials. Further vibration tests confirm the ultra-low frequency vibration isolation capability of the proposed mechanical metamaterials. The mechanism of QZS stems solely from the structural geometry of the curved beams and is therefore materials-independent. This design strategy opens a new avenue for innovating compact and scalable QZS isolators with multiple working ranges.