Layered hybrid lattice architectures for broadband electromagnetic absorption and improved structural stiffness

Electromagnetic interference (EMI) presents a critical challenge across application areas such as wireless communication networks, defense technologies, and electronic devices. Although metamaterial absorbers offer excellent electromagnetic (EM) wave attenuation, their limited mechanical stiffness restricts their use in structurally demanding environments. This study introduces a new class of layered hybrid lattice absorbers that concurrently achieve broadband EM wave absorption and enhanced mechanical stiffness. Three-layer hybrid lattices are developed by combining simple cubic (SC), body-centered cubic (BC), and octet-truss (OT) architectures in diverse configurations. The relationship between broadband absorption and mechanical performance is then examined as a function of lattice arrangement. Finite element simulations are used to evaluate EM responses and effective stiffness across the 4-18 GHz frequency range. The simulations show that positioning an OT lattice in the upper layer leads to average EM absorption exceeding 95% due to improved impedance matching, whereas the middle layer primarily regulates how the residual energy is redistributed within the multilayer system. Incorporating an SC lattice in the lower layer enhances the structure's load-bearing capacity. We find that the OT-SC-SC configuration maintains strong EM absorption while providing approximately 36% greater stiffness in the out-of-plane (vertical stacking) direction and 118% greater stiffness in the in-plane directions relative to the benchmark OT-OT-OT configuration. These findings highlight that tailored spatial arrangement of lattice types enables simultaneous optimization of EM and mechanical functionalities. Positioning an OT lattice at the top and an SC lattice at the bottom is demonstrated to be an effective strategy for developing multifunctional metamaterial absorbers. This approach offers a foundational framework for next-generation absorbers targeting advanced EMI shielding and mechanically resilient applications.