Band gap characterization of complex unit cell geometries for 3D phononic crystals

摘要

We report on experimental characterization of acoustic band gaps for complex three-dimensional phononic crystals. Utilizing 3D unit cell geometries arranged in a cubic lattice, we can achieve uniquely wider band gaps with stronger suppression of acoustic waves than possible with two-dimensional realizations. Beyond our previously established simple cubic arrangement of three cylindrical holes derived from the classic 2D square array of holes, we investigate unit cells comprising a spherical cavity, a rectangular scaffold, and a spherical ball connected by cylindrical beams. All samples have been additively manufactured using microstereolithography printing in the same geometric arrangement with a lattice constant of 1 mm and variations of the characteristic dimensions to achieve different volumetric filling factors. Maximum band gap widths over 1 MHz at gap center frequencies around 750 - 850 kHz have been measured.