Natural materials have evolved unique microstructures to defend themselves against predators or harsh environments, such as the brick-and-mortar architecture of seashells, the porous graded architecture of bamboo, and the highly ordered prisms of enamel. The presence of these spatially ordered structures introduces different toughening mechanisms to avoid catastrophic fracture under stress. Similar spatial ordering can also be achieved in metamaterials which allow for synthetic composites with extraordinary physical properties not found in natural materials like negative dielectric constant, negative refractive index, structural color, etc. by designing the shape, dimension, and orientation of the unit cell. The current challenge in both fields lies in the fabrication of dense metamaterials at macroscopic scale with the degree of structural control and effective toughening mechanisms.
My research aims to develop new manufacturing techniques for tough bioinspired metamaterials with improved damage resistance. One project is to characterize the microstructure of the natural material itacolumite, followed by structural design and component optimization to obtain tough composites with desired properties using additive manufacturing. The other project is to assemble anisotropic building blocks into highly ordered colloidal crystals and then by selecting suitable interfaces to trigger different toughening mechanisms, such as damage delocalization at the macroscopic scale.
This work is supported by the ERC Starting Grant SSTEEL.