Design and Fabrication Challenges for Millimeter-Scale Three-Dimensional Phononic Crystals

• Published in: Crystals (Basel) Vol. 7; no. 11; p. 348
• Main Authors: Lucklum, Frieder, Vellekoop, Michael
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 15.11.2017
• Subjects: 3D unit cell; additive manufacturing; complete acoustic band gap; directional band gap; fabrication challenges; Lattices (mathematics); Mathematical models; Numerical methods; phononic crystals; Propagation modes; Three dimensional models; transmission loss; Wave propagation
• ISSN: 2073-4352; 2073-4352
• DOI: 10.3390/cryst7110348

While phononic crystals can be theoretically modeled with a variety of analytical and numerical methods, the practical realization and comprehensive characterization of complex designs is often challenging. This is especially important for the nearly limitless possibilities of periodic, three-dimensional structures. In this contribution, we take a look at these design and fabrication challenges of different 3D phononic elements based on recent research using additive manufacturing. Different fabrication technologies introduce specific limitations in terms of, e.g., material choices, minimum feature size, aspect ratios, or support requirements that have to be taken into account during design and theoretical modeling. We discuss advantages and disadvantages of additive technologies suitable for millimeter and sub-millimeter feature sizes. Furthermore, we present comprehensive experimental characterization of finite, simple cubic lattices in terms of wave polarization and propagation direction to demonstrate the substantial differences between complete phononic band gap and application oriented directional band gaps of selected propagation modes.