3D Printed Electromagnetic Wave Absorber based on Carbon Black-Based Load-Bearing Metastructure

As electronic equipment becomes more diverse and miniaturized due to advances in science and technology, addressing the issues of interference shielding and electromagnetic (EM) radiation absorption becomes increasingly important. Carbon-based composites combined with porous metastructures are lightweight, flexible and their EM properties can be modified in a desired frequency band, making them suitable for a variety of applications. However, the low density of these structures intrinsically limits their mechanical properties.<br/>In this study, we report a multifunctional broadband metamaterial absorber (MBMA) with EM wave absorption, energy absorption, and constant relative stiffness using a bending-dominated lattice structure based on Kelvin Foam comprising carbon-black composite polylactic acid (PLA). Using computational simulation, EM wave characteristics are optimized by adjusting structural parameters such as beam diameter and unit cell size, and intrinsic material properties like dielectric constant according to carbon black filler concentration. Then, the optimized structure is additively manufactured for experimental validation to demonstrate the feasibility of actual implementation. The developed MBMA achieves an outstanding broadband (C-Ku band) EM wave absorption rate (&gt;90%, average 95.9%) even at densities as low as cork (200 kg/m³), with a maximum absorption of 99.1% at 15.8. GHz. Regardless of the layer stacking direction, the relative density-to-relative stiffness ratio is close to 2.0, maintaining the theoretical stiffness of Kelvin Foam. The experimentally measured performances using 3D-printed MBMA are almost identical to the theoretically confirmed simulation results, validating the design and fabrication of the developed structure. This rational design strategy using 3D lattice structures can inspire multifunctionality of mechanical metamaterials including EM wave absorption, enabled by developing various polymer-based materials and unit cell structures.