Sound and mechanical impedance behaviors observed in multifunctional modular bio-inspired lattice metamaterials

• A multifunctional bio-inspired lattice metamaterials (MBLM) is proposed for sound absorption and energy dissipation. • The sound absorption of MBLM is attributed to the Helmholtz resonator, curved micro-perforated plate, and coupling effect. • The component ratio and strut diameter of MBLM have vital effects on energy absorption. • The multifunctional performance of MBLM was investigated through experimental, numerical, and theoretical methods. Noise and impact hazards are ubiquitous in engineering applications, creating an urgent demand for multifunctional materials capable of absorbing both acoustic and stress wave energy. However, the design of such materials presents challenges, including complex microstructure fabrication, multi-physics field coupling effects, and scalability issues. Recent advancements in decoupled design, additive manufacturing, and optimization technology have led to the development of multifunctional metamaterials. A layered multifunctional bio-inspired lattice metamaterial (MBLM) is presented in this work, drawing on inspiration from the body armor of glyptodonts and the structural features of turtle shells. The multi-layered design integrates a Helmholtz resonator with an internal micro-perforated curved plate to achieve broadband acoustic absorption in the two outer dense layers. The central layer features a hybrid BCC-Octet lattice structure, which acts as an efficient energy absorber. Experimental, numerical, and theoretical approaches were employed to systematically assess the sound absorption and impact energy performance of MBLM. The results demonstrate that MBLM achieves a stable energy absorption deformation pattern and quasi-perfect broadband sound absorption, with an average absorption coefficient exceeding 0.9 within the target frequency range of 750 Hz to 1610 Hz. Overall, this work offers an innovative approach to the design of multifunctional metamaterials.