X‐QZS Metamaterial: A Novel Mechanical Metamaterial of Morphological Nonlinearity via Topological Transformations

The key challenge for advancing next‐generation mechanical metamaterials lies in systematically discovering and harnessing the beneficial nonlinear mechanical characteristics. This work introduces a novel class of mechanical metamaterials exhibiting morphological nonlinearity of mechanics in stiffness and Poisson's ratio, achieving purposeful nonlinear performance with quasi‐zero stiffness (QZS) through topological transformations from X‐shaped rigid‐body mechanism. The proposed topology transformation miniaturizes, reshapes, and reprograms tailorable nonlinear stiffness of solid mechanism into elastic metamaterial. Governed by compliant elements and nonlinear meta‐atoms, architected matrices culminate in a novel family termed as X‐QZS metamaterial. Localized topology faithfully emulates the nonlinear kinematics of their rigid‐body counterparts, meanwhile meta‐atoms incubate tailorable nonlinear stiffness with topological morphologies. Assembled in nonlinear Poisson's ratio matrix, X‐QZS matrix reprograms nonlinear stiffness from meta‐atomic level into stabilized structural pattern. Experimental demonstrations validate the presence of QZS in multiple configurations as analytically determined in the topology design, achieving wide‐bandwidth vibration isolation starting from 2 Hz and attenuating vibration energy from external sources by more than 98%. X‐QZS metamaterial with tailorable dual nonlinearity and its topology pave the way of developing functional mechanical metamaterials transferred from rigid‐body structures, which reprogram and reshape large‐scale mechanisms into continuum deformable metamaterial of equivalent performance.