Wave propagation in architected shellular metamaterials

A shell-based cellular solid or Shellular is commonly composed of a three-dimensional (3D) unit cell of continuously smooth and non-self-intersecting shells. Shellulars offer less sensitivity to stress concentration and architectural defects than truss/plate-like lattices, and therefore are more promising candidates for realizing ultralight resilient architected materials. The pre-fabricated topological features of shellulars hold great promise for creating mechanical metamaterials with unparalleled properties. The underlying topology of shell surfaces can be tailored in post-fabrication state by harnessing the shell's structural instability. Despite promising properties of shellulars, exploration of their dynamic properties and utilization of multistability for in-situ tuning of elastic and acoustic wave bandgaps remains largely unexplored. Capitalizing on shellular's outstanding properties and utilizing additive manufacturing techniques, objectives of this international research, between McGill University and Conservatoire national des arts et métiers (Cnam) in collaboration with Dalhousie University, is to study the effect of topological straits of intact/perforated shellulars on the propagation of elastic and acoustic waves, opening up new avenues for their application in the insulation of probes from elastic waves during the launch of aerospace vehicles, isolating buildings from the earthquake shock wave, and lightweight multifunctional protective sporting goods. This project represents a significant opportunity to strengthen Canada's innovation capacity. The HQP will acquire critical skills and expertise for performing phononic and acoustic wave propagation tests, exploring deformation modes, and deriving analytical models for dynamic properties of shellulars. The exposure of HQP to advanced vibration test facilities and the understanding of experimental methods for capturing wave propagation in shellulars will provide HQP with a knowledge that is currently underrepresented in Canadian research community. The gained knowledge by the team can enhance material development innovation in the area of metamaterials with programmable properties within the Canadian academic and industry sectors.