Structure-Driven Programmable Metamaterials for Adaptive Microwave-Infrared Regulation and Impact Protection

Adaptive materials that can simultaneously regulate radar scattering, infrared signatures, and mechanical impact response are highly desirable but remain difficult to realize because most multifunctional systems rely on independent functional layers rather than direct structure-property coupling. Here, we report a pneumatically programmable multilayer nested honeycomb metamaterial in which an accordion-inspired airbag continuously reconfigures the structural height, thereby tuning electromagnetic propagation pathways, impedance matching, and mechanical buffering. Meanwhile, a bottom-mounted, independently addressable heating array provides programmable thermal regulation for infrared camouflage and temperature-coded information display. A 3D-printed PLA@CF/Fe3O4 absorbing framework, optimized by a gray wolf algorithm, enables broadband, and tunable microwave attenuation across 2-18 GHz, with an average reflection loss down to -15.46 dB and robust oblique-incidence stability. Active heating to approximately 40°C produces negligible variation in microwave absorption, while the pneumatic unit maintains stable impact-buffering performance over 50 repeated impacts. Under impact loading, the rigid cover, load-redistributing honeycomb, and deformable pneumatic module act cooperatively to dissipate energy and suppress structural damage. This work establishes a structure-driven strategy for adaptive multispectral stealth and protection systems.