Abstract
Porous phononic crystal plates (PhPs) that are produced by perpendicular perforation of a uniform plate have well-known characteristics in selective manipulation (filtration, resonation, and steering) of guided wave modes. This paper introduces novel designs of porous PhPs made by an oblique perforation angle. Such obliquely perforated PhPs (OPhPs) have a non-uniform through-the-thickness cross section, which strongly affects their interaction with various wave mode types and therefore their corresponding phononic properties. Modal band analysis is performed in unit-cell scale and variation of phononic bandgaps with respect to the perforation angle is studied within the first 10 modal branches. Unit-cells with arbitrary perforation profile as well as unit-cells with optimized topology for maximized bandgap of fundamental modes are investigated. It is observed that the oblique perforation has promising effects in enhancing the unidirectional and/or omnidirectional bandgap efficiency, depending on the topology and perforation angle of OPhP.
Highlights
Phononic crystals (PhCrs) are lattice structures that can manipulate elastic waves in an extraordinarily way through their periodic microstructure [1,2,3,4,5,6,7,8,9,10]
Relative bandgap width (RBW), which is defined as bandgap width divided by mid gap frequency, is normally used to indicate the bandgap efficiency of PhCrs
Bandgap in ΓX and (b,d) bandgap in ΓXMΓNM. This partial bandgap corresponds to the unidirectional wave propagation in x-axis along which. This partial bandgap corresponds to the unidirectional wave propagation in x-axis along which oblique perforation is performed in zx-plane
Summary
Phononic crystals (PhCrs) are lattice structures that can manipulate elastic waves in an extraordinarily way through their periodic microstructure [1,2,3,4,5,6,7,8,9,10]. The meta-surfaces results confirmwith the Earlier studies have shown the abnormal dispersion properties of tapered promising effect of oblique perforation in enhancing partial (unidirectional) and/or complete axisymmetric non-uniform through the thickness profile [31,32]. Twoofdistinct designs symmetric andtwo asymmetric through-the-thickness constitution, cells, and selected topologies to be examined are presented and constitutive equations of modal band with respect to the mid-plane, are proposed. The two proposed designs of OPhPs, relevant unit-cells, and selected topologies to be examined are presented and constitutive equations by of modal. The calculated band structure and of selected topologies perforation ofare a uniform background plate atmodal an angle θ with respect to RBW the plate’s normal axis
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