scholarly journals Robust separation of topological in-plane and out-of-plane waves in a phononic crystal

2022 ◽  
Vol 5 (1) ◽  
Author(s):  
Myung-Joon Lee ◽  
Il-Kwon Oh
Keyword(s):  
Elastic Wave ◽  
Phononic Crystal ◽  
Plane Waves ◽  
Degree Of Freedom ◽  
Wave Separation ◽  
Simultaneous Control ◽  
Accidental Degeneracy ◽  
Out Of Plane ◽  
Wave Path ◽  
The Rich

AbstractValley degree of freedom, associated with the valley topological phase, has propelled the advancement of the elastic waveguide by offering immunity to backscattering against bending and weak perturbations. Despite many attempts to manipulate the wave path and working frequency of the waveguide, internal characteristic of an elastic wave such as rich polarization has not yet been utilized with valley topological phases. Here, we introduce the rich polarization into the valley degree of freedom, to achieve topologically protected in-plane and out-of-plane mode separation of an elastic wave. Accidental degeneracy proves its real worth of decoupling the in-plane and out-of-plane polarized valley Hall phases. We further demonstrate independent and simultaneous control of in-plane and out-of-plane waves, with intact topological protection. The presenting procedure for designing the topologically protected wave separation based on accidental degeneracy will widen the valley topological physics in view of both generation mechanism and application areas.

Optimization of Phononic Crystals for the Simultaneous Attenuation of Out-of-Plane and In-Plane Waves

2011 ◽  
Author(s):  
Osama R. Bilal ◽  
Mahmoud I. Hussein
Keyword(s):  
Genetic Algorithm ◽  
Phononic Crystal ◽  
Plane Waves ◽  
Phononic Crystals ◽  
Gap Size ◽  
Two Dimensional ◽  
Dispersion Characteristics ◽  
Out Of Plane ◽  
Optimization Methodology ◽  
Application Specific

The topological distribution of the material phases inside the unit cell composing a phononic crystal has a significant effect on its dispersion characteristics. This topology can be engineered to produce application-specific requirements. In this paper, a specialized genetic-algorithm-based topology optimization methodology for the design of two-dimensional phononic crystals is presented. Specifically the target is the opening and maximization of band gap size for (i) out-of-plane waves, (ii) in-plane waves and (iii) both out-of-plane and in-plane waves simultaneously. The methodology as well as the resulting designs are presented.

scholarly journals A Phononic Crystal with Differently Configured Double Defects for Broadband Elastic Wave Energy Localization and Harvesting

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 643
Author(s):  
Soo-Ho Jo ◽  
Byeng D. Youn
Keyword(s):  
Elastic Wave ◽  
Wave Energy ◽  
Phononic Crystal ◽  
Square Lattice ◽  
Energy Localization ◽  
Piezoelectric Patch ◽  
Single Defect ◽  
Piezoelectric Energy ◽  
Piezoelectric Effects ◽  
Elastic Wave Energy

Several previous studies have been dedicated to incorporating double defect modes of a phononic crystal (PnC) into piezoelectric energy harvesting (PEH) systems to broaden the bandwidth. However, these prior studies are limited to examining an identical configuration of the double defects. Therefore, this paper aims to propose a new design concept for PnCs that examines differently configured double defects for broadband elastic wave energy localization and harvesting. For example, a square-pillar-type unit cell is considered and a defect is considered to be a structure where one piezoelectric patch is bonded to a host square lattice in the absence of a pillar. When the double defects introduced in a PnC are sufficiently distant from each other to implement decoupling behaviors, each defect oscillates like a single independent defect. Here, by differentiating the geometric dimensions of two piezoelectric patches, the defects’ dissimilar equivalent inertia and stiffness contribute to individually manipulating defect bands that correspond to each defect. Hence, with adequately designed piezoelectric patches that consider both the piezoelectric effects on shift patterns of defect bands and the characteristics for the output electric power obtained from a single-defect case, we can successfully localize and harvest the elastic wave energy transferred in broadband frequencies.

SOFTENING BRANCHES OF A TWO-DEGREE-OF-FREEDOM SYSTEM INDUCED BY SPATIAL BUCKLING

2006 ◽  
Vol 06 (04) ◽  
pp. 493-512 ◽  
Author(s):  
NOËL CHALLAMEL
Keyword(s):  
Structural Model ◽  
Structural Parameters ◽  
Degree Of Freedom ◽  
Lateral Loading ◽  
Load Parameter ◽  
Imperfection Sensitivity ◽  
Softening Effect ◽  
Out Of Plane ◽  
Secondary Bifurcation ◽  
Two Degree Of Freedom

The aim of this paper is to show how geometrical non-linearity may induce equivalent softening in a simple two-degree-of-freedom spatial elastic system. The generic structural model studied is a generalization of Augusti's spatial model, incorporating lateral loading. This model could be used as a teaching model to understand the softening effect induced by out-of-plane buckling. The lateral loading in the plane of maximal stiffness is considered as the varying load parameter, whereas the vertical load is perceived as a constant parameter. It is shown that a bifurcation occurs at the critical horizontal load. The fundamental path becomes unstable, beyond this critical value. However, two symmetrical bifurcate solutions appear, whose stability depend on the structural parameters value. No secondary bifurcation is observed for this system. The presented system possesses imperfection sensitivity, and imperfection insensitivity, depending on the values of the structural parameters. In any case, for sufficiently large rotations, collapse occurs with unstable softening branches induced by spatial buckling.

Enhanced energy transfer and conversion for high performance phononic crystal-assisted elastic wave energy harvesting

Nano Energy ◽  
2020 ◽  
Vol 78 ◽  
pp. 105226 ◽  
Author(s):  
Tae-Gon Lee ◽  
Soo-Ho Jo ◽  
Hong Min Seung ◽  
Sun-Woo Kim ◽  
Eun-Ji Kim ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Energy Harvesting ◽  
Elastic Wave ◽  
Wave Energy ◽  
High Performance ◽  
Phononic Crystal ◽  
Elastic Wave Energy

Design of a 6-DOF VCM-Driven Micro Stage

2014 ◽  
Vol 532 ◽  
pp. 3-6 ◽  
Author(s):  
Jae Heon Jeong ◽  
Myeong Hyeon Kim ◽  
Si Woong Woo ◽  
Da Hoon Ahn ◽  
Dong Pyo Hong
Keyword(s):  
Resonant Frequency ◽  
Laser Interferometer ◽  
Voice Coil Motor ◽  
Degree Of Freedom ◽  
Out Of Plane ◽  
Gap Sensors ◽  
Moving Magnet ◽  
High Resonant Frequency

This paper presents design of micro stage performing 6 degree-of-freedom (DOF) motions, which actuated by voice coil motor (VCM). The VCMs generate forces to perform in-plane motions and out-of-plane motions. The stage is supported by springs for compensating mass of the moving part of the stage and the stiffness of the springs has been chosen to meet the moving range requirement and to have high resonant frequency at the same time. Moving magnet type has been selected against moving coil type due to few merits of the type. The size of the stage is 380 X 380 X 60 mm3 and the motions are measured by laser interferometer and gap sensors.

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