Design and applications of multifunctional mechanical metamaterials for intelligent response

Mechanical metamaterials achieve extraordinary mechanical properties beyond those of natural materials by leveraging structural topology， multi-material integration， and multiscale design. These artificial systems offer promising solutions to overcome the intrinsic limitations of conventional materials， enabling their application in demanding fields such as aerospace， deep-sea exploration， and intelligent equipment. In recent years， driven by innovations in physical mechanisms， design strategies， and manufacturing techniques， the field has rapidly evolved from focusing on single-function materials to multifunctional， programmable， and stimuli-responsive systems. Unlike traditional metamaterials with static and singular mechanical responses such as low-frequency vibration isolation， negative Poisson’s ratio， or directional stiffness， multifunctional mechanical metamaterials enable dynamic control of force–displacement behavior， Poisson’s ratio， and wave propagation through structural reconfiguration. This review summarizes recent advances in the design and application of multifunctional mechanical metamaterials with intelligent responsiveness. We focus on the development of quasi-zero stiffness structures， auxetic systems， and bandgap-tunable lattices， emphasizing their programmability and multimodal responses under external fields. Finally， future perspectives are discussed， including the need for highly integrated unit cell designs， in-situ adaptive modeling under multiphysics coupling， and the exploration of novel physical principles， smart materials， and advanced manufacturing technologies. These efforts aim to shift the paradigm of mechanical metamaterials from passive architectures to active， intelligent systems suitable for complex service environments.