Microstructural design for elastic wave attenuation in 3D printed nacre-like bioinspired metamaterials lightened with hollow platelets

In this work, the wave propagation properties of lightened bioinspired composite materials are investigated. A new lightened nacre-like microstructure is proposed demonstrating that the incorporation of hollow platelets inside the soft matrix and the application of specific prestress states represent a viable way for tuning the complete band gaps range without varying the geometry length scale and also improving the mechanical properties in terms of homogenized tangent moduli. The wave dispersion relations are obtained by adopting the Bloch-Floquet theory to investigate the appearance of complete band gaps for several geometrical and material parameters (platelets aspect ratio, matrix joints thickness, void volume fraction, and shear modulus contrast). The obtained results reveal new combinations of geometrical and material parameters for which excellent wave absorption capabilities in nacre-like periodic composite microstructure are obtained thanks to the application of prestress states which may provide new opportunities in the microstructural design of 3D printed composite metamaterials.