Data-driven design of lightweight, interface-free metamaterial composites tailored for enhanced broadband electromagnetic absorption with robust mechanical properties

The rapid advancement of gigahertz-frequency technologies in industrial and military mobility platforms demands lightweight metamaterials with both electromagnetic wave (EMW) control and mechanical robustness, yet a comprehensive strategy for designing such multifunctionality remains unexplored. This study introduces a data-driven optimization framework for lightweight, interface-free metamaterial composites (DOMC) tailored for superior broadband EMW absorption with robust mechanical functionalities. By simulating over 7500 combinations of material combination, unit-cell geometries, gradient relative densities, porous layers, and panel configurations, the framework optimizes impedance matching, dielectric properties, and mechanical properties. The screened unit-cell-based gradient metamaterials having the optimized configuration via the data-driven design is fabricated as 3D-printed carbon black/polylactic acid-based sandwich composites in a single step to create interface-free, seamless multimaterial architectures. The resulting DOMC achieves an average EMW absorption of 97.5 % (peak absorption of 99.7 %) with a full effective absorption bandwidth (≥90 % absorption) spanning 4–18 GHz, and an average reflection loss of −19.5 dB with a minimum of −52.9 dB at 4.9 GHz. Furthermore, it outperforms traditional bending-dominated metamaterials with 50 % higher energy absorption and enhanced stiffness while maintaining a lightweight profile. These results underscore the potential of integrating data-driven design with additive manufacturing to develop lightweight, multifunctional metamaterials for electronics, communications, and aerospace.