Bandgap engineering of three-dimensional phononic crystals in a simple cubic lattice

In this work, we present a comprehensive theoretical and experimental study of three-dimensional phononic crystals arranged in a simple cubic lattice. The band structure is analytically modeled as a 3D mass spring system and numerically calculated within the corresponding simple cubic Brillouin zone. We report on a design yielding a record bandgap of 166% relative width, validated by simulations and measurements of longitudinal and shear wave transmission in different spatial directions. In the additively fabricated samples, gap suppression reaches -80 dB relative to a solid reference. Comparison of different unit cell geometries showcases approaches to engineer gap width and suppression, as well as transmission bands outside the gap. Published by AIP Publishing.