A designer’s challenge: Unraveling the architected structure of deep sea sponges for lattice mechanical metamaterials

Biomimetic and Bioinspired designs have been investigated due to the advances in modeling, mechanics and experimental characterization of structural features of living organisms. To accomplish bioinspiration for fields such as robotics, adhesives and smart materials, it is required to comprehend how Nature accomplished enhanced mechanical behavior. Among the plethora of complex organisms spanning at different lengthscales, the deep sea sponge Euplectella Aspergillum has been of particular interest due to its lattice structure that can be the framework to design mechanical metamaterials. However, despite its intriguing morphology, constraints in the fabrication and modeling of scalable and nonuniform materials has hindered the study of its mechanical performance and how to harness it. Moreover, a comprehensive FEA model that encompasses the whole spectrum of its constitutive and structural performance has not been reported. In this study, it is aimed to characterize and model the mechanical behavior of this sponge from a structural standpoint. Utilizing various experimental techniques, an FEA mechanical model is developed to study the nonlinear buckling analysis of the sponge's lattice structure and its resilience to failure. Finally, through topology optimization and sensitivity analysis, a new mechanical metamaterial is proposed. Our results elucidate how mechanical characterization and FEA modeling can be employed for a deeper understanding of Nature's tailored hierarchy and the design of metamaterials.