Analysis of Bending Waves in Phononic Crystal Beams with Defects

Guo, Yongqiang; Li, Longfei; Chuang, Kuo-Chih

doi:10.3390/cryst8010021

Cited by 19 publications

(6 citation statements)

References 71 publications

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“…The most commonly used method is the transfer matrix method. 27 The transfer matrix of supercell is obtained by multiplying the transfer matrices of perfect cells and the defective cell…”

Section: Theoretical Modelmentioning

confidence: 99%

Characteristics of defect states in periodic railway track structure

Yan

Zhao

Wang

2021

Journal of Low Frequency Noise, Vibration and Active Control

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To overcome the ill-conditioned matrix problem of the traditional transfer matrix method, the Floquet transform method and supercell technology are used to study the defect states of the periodic track structure. By solving the equations of the supercell directly, the propagation characteristics of elastic waves in the track structure with defects are analyzed. The existence of defects destroys the periodicity of track structure, thus resulting in the formation of defect states within the band gaps. Moreover, the elastic wave is localized near the defect position at the frequency of the defect state. The formation mechanism of the defect state in track structure can be explained by the local resonance at the defect. With the expansion of the defect range, the number of local resonance modes that can be formed near the defect increases, thus generating multiple defect states. Furthermore, the defect state enhances the vibration of the structure adjacent to the defect. Therefore, the vibration transmission coefficient in a finite-length range can be used to detect the defect characteristics in the track structure, and the defect degree can be evaluated by the peak frequency of the vibration transmission coefficient within the band gap.

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“…The most commonly used method is the transfer matrix method. 27 The transfer matrix of supercell is obtained by multiplying the transfer matrices of perfect cells and the defective cell…”

Section: Theoretical Modelmentioning

confidence: 99%

Characteristics of defect states in periodic railway track structure

Yan

Zhao

Wang

2021

Journal of Low Frequency Noise, Vibration and Active Control

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“…Here, a defect can be artificially introduced by replacing one unit cell with a different structure that disorders the unit-cell periodicity. This defect imposition provokes the creation of one or more flat passbands (called defect bands) within a phononic bandgap [17][18][19]. Surprisingly, a PnC displays wave-energy concentration near the defect in the form of different vibrational modes (called defect-mode shapes) at each defect-band frequency [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Double piezoelectric defects in phononic crystals for ultrasonic transducers

Jo¹,

Lee²,

Yoon³

et al. 2023

J. Phys. D: Appl. Phys.

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Significant prior research has explored elastic wave-energy localization via a defect mode of a phononic crystal (PnC). The integration of defect-introduced PnCs and piezoelectric materials has paved the path for the development of new conceptual products for applications in energy harvesters, wave filters, and ultrasonic sensors. Recently, an attempt has been made to deviate from this paradigm and design an ultrasonic transducer that generates elastic waves. Unfortunately, the previous works have been limited to a single-defect situation. Therefore, as an advanced approach, this work aims to expand the PnC design space into double defects, which will make the ultrasonic transducer useful at several frequencies. As a first step, this study targets longitudinal wave generation. To predict the wave-generation performance, a previous analytical model that was built for energy-harvesting purposes under a single-defect situation is modified to be suitable for the present wave-generation purpose under a double-defect situation. Moreover, two parametric studies are executed to analyze how the output responses change based on changes to the input voltage setting and the spacing between the double defects. We hope that these ultrasonic transducers can be potentially applicable for nondestructive testing in structural health monitoring and ultrasonic imaging in medical science.

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“…The incorporation of a disordering structure (called a defect) in a PnC through the partial disruption of periodicity can generate characteristics within the band gap, namely, the appearance of flat defect bands [ 22 ]. Each defect band exhibits a different energy-localized displacement field of the PnC (called a defect-mode shape) at each defect-band frequency [ 23 , 24 ], and this property ensures high amplification of the elastic-wave energy within the defect [ 25 – 27 ]. Hence, piezoelectric devices with defects can generate significantly improved electric power.…”

Section: Introductionmentioning

confidence: 99%

L-shape triple defects in a phononic crystal for broadband piezoelectric energy harvesting

Yoon

Shin

et al. 2022

Nano Convergence

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This study proposes a phononic crystal (PnC) with triple defects in an L-shape arrangement for broadband piezoelectric energy harvesting (PEH). The incorporation of defects in PnCs has attracted significant attention in PEH fields owing to properties such as energy localization and amplification near the defect. Several studies have been conducted to enhance output electric power of PnC-based PEH systems with single defects. However, it is susceptible to the limitations of narrow bandwidth. Recently, double-defect-incorporated systems have been proposed to widen the PEH bandwidth via defect-band splitting. Nevertheless, the PEH performance rapidly decreases in the frequency range between the split defect bands. The limitations of single- and double-defect-incorporated systems can be resolved by the incorporation of the proposed design concept, called the L-shape triple defects in a PnC. The isolated single defect at the top vertex of the letter ‘L’ compensates for the limitations of double-defect-incorporated systems, whereas the double defects at the bottom vertices compensate for the limitations of the single-defect-incorporated systems. Hence, the proposed design can effectively confine and harvest elastic-wave energy over broadband frequencies while enhancing the application of single and double defects. The effectiveness of the proposed design concept is numerically validated using the finite element method. In the case of a circular hole-type PnC, it is verified that the PnC with L-shape triple defects broadens the bandwidth, and improves the output voltage and electric power compared with those of single- and double-defect-incorporated systems. This study expands the design space of defect-incorporated PnCs and might shed light on other engineering applications of the frequency detector and elastic wave power transfer.

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Analysis of Bending Waves in Phononic Crystal Beams with Defects

Cited by 19 publications

References 71 publications

Characteristics of defect states in periodic railway track structure

Characteristics of defect states in periodic railway track structure

Double piezoelectric defects in phononic crystals for ultrasonic transducers

L-shape triple defects in a phononic crystal for broadband piezoelectric energy harvesting

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