Multidimensional twisted mechanical metamaterials with programmable stiffness for adaptive impact protection

Compression-torsion coupling mechanical metamaterials (CTCMMs) transcend classical Cauchy continuum mechanics by incorporating torsional degrees of freedom, unlocking new avenues for dissipation and damping. However, conventional CTCMMs are typically confined to fixed spatial configurations and mechanical properties post-fabrication, limiting their adaptability in dynamic environments. Here, we present a universal strategy for constructing multidimensional chiral CTCMMs—from 2D to 4D—via a modular, discrete assembly approach. Through a combination of experimental validation and theoretical modeling, we reveal how structural dimensionality governs mechanical behavior: Specifically, 2D CTCMMs enable programmable load-bearing capacity and energy absorption via chirality and topological tuning; 3D CTCMMs achieve isotropic cushioning and damping performance; while 4D CTCMMs incorporate temporal functionality, enabling continuous and reversible modulation of stiffness and impact response through thermally induced shape-memory effects. Proof-of-concept demonstrations—including fragile-object landing protection and drone collision mitigation—underscore their potential as lightweight, reusable, and adaptive protective systems. Our work lays the groundwork for the development of next-generation mechanical metamaterials, with broad implications in energy dissipation technologies, protective packaging, and resilient robotic systems.