Topology-Orchestrated Multi-physical Energy Control in Turtle Shell-Inspired Metamaterials.

Achieving metamaterials that are simultaneously mechanically, acoustically, and thermally functional remains a central challenge in architected material design. In this research, we report a turtle shell bioinspired multifunctional lattice metamaterial (BMLM) that overcomes this limitation through topology-driven hybrid-coupling of distinct dissipation and transport pathways within a single hierarchical framework. The integration of arcuate plate-strut geometries with engineered microporosity enables coordinated mechanical energy absorption, acoustic attenuation, and convective thermal transport. Experimentally validated, the proposed architecture achieves an exceptional specific compressive energy absorption of 55.7 kJ/kg alongside broadband acoustic performance, exhibiting an average sound absorption coefficient of 0.954 and near-unity absorption (>0.9) sustained continuously from 2150 to 4250 Hz. Notably, the structure maintains acoustic stability under severe deformation; even at 40% compressive strain, absorption remains above 0.9 across a 2.1 kHz bandwidth, demonstrating deformation-resilient functionality. Moreover, the interconnected open-cell topology facilitates efficient airflow and convective thermal dissipation through its high surface-area-to-volume ratio, comparing superior to standard plate-fin heat sinks. Collectively, this work establishes a topology-driven strategy for designing bio-inspired metamaterials with robust, cross-domain performance.