Topological interface modes in 3D-printed triply periodic minimal surface phononic crystals

Abstract

Triply periodic minimal surface (TPMS)-based continuous structures have recently attracted increased attention due to their remarkable mechanical properties, such as high strength-to-weight ratio, impact resistance, and energy absorption capabilities. In this study, we investigate topological interface modes in I-WP (Wrapped Package) TPMS geometry. Inspired by a one-dimensional (1D) Su–Schrieffer–Heeger (SSH) model, we design 1D elastic Phononic Crystals (PCs) made of sheet-based I-WP minimal surface geometry. By manipulating the geometry of the I-WP minimal surface, we open the degeneracies formed at the edges of the Brillouin zone to create band-folding-induced bandgaps. We then design a 1D dimerized chain of two topologically distinct unit cells of I-WP minimal surface to create an interface and introduce topological interface modes. Numerical simulations are performed to study the band structure and topological transition properties of the proposed 1D PC. In addition, we show that hybridizing alternative I-WP unit cells of different relative densities can also break the inversion symmetry of the periodic structure in contrast to manipulating the geometry. The 1D PC made of hybridized I-WP geometry is then used to realize topological interface modes. The proposed 1D PCs are additively manufactured to experimentally validate the existence of topological interface modes. Our work provides an efficient method for TPMS structures to produce multifunctional devices that can support superior load-bearing capabilities as well as robust topological phase properties.