Quasi-zero stiffness chiral combined metamaterials for broadband vibration isolation and load robustness

Existing quasi-zero-stiffness (QZS) metamaterials exhibit extremely narrow operating ranges. Consequently, they are highly susceptible to stiffness hardening and isolation-performance degradation caused by large-amplitude axial vibrations or payload-induced equilibrium-position shifts. To overcome this bottleneck within a single compact continuum, this paper proposes a chiral re-entrant honeycomb (CRC) metamaterial. The design is inspired by the shear-resistant butterfly joints and rotating window lattices found in traditional Chinese timber architecture. By deeply coupling microscopic ligament translational folding with chiral node rotation, this metamaterial establishes a highly coordinated nonlinear deformation path that effectively widens the quasi-zero-stiffness stroke. Eight derived topologies are systematically evaluated and compared using quasi-static compression, broadband axial vibration testing, and a single-degree-of-freedom nonlinear dynamic model. The results indicate that under a 1.5 kg preload, the S-CHAC configuration achieves an initial isolation frequency as low as 1.0 Hz, a peak transmission loss of -43.11 dB, and a normalized quasi-zero stiffness stroke of up to 66.7%. Furthermore, this configuration maintains stable isolation performance under axial payloads ranging from 1 to 2 kg. This study establishes a three-dimensional evaluation framework that integrates frequency-domain characteristics and static robustness. Overall, this work offers a novel topological design strategy and evaluation system for extending the QZS operating stroke and reducing the displacement and load sensitivity of conventional QZS metamaterials.