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Статті в журналах з теми "Vibration bandgap"
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Anigbogu, Winner, and Hamzeh Bardaweel. "A Metamaterial-Inspired Structure for Simultaneous Vibration Attenuation and Energy Harvesting." Shock and Vibration 2020 (June 13, 2020): 1–12. http://dx.doi.org/10.1155/2020/4063025.
Повний текст джерелаАнотація:
In this article, a magnetomechanical metamaterial structure capable of simultaneous vibration attenuation and energy harvesting is presented. The structure consists of periodically arranged local resonators combining cantilever beams and permanent magnet-coil systems. A prototype of the metamaterial dual-function structure is fabricated, and models are developed. Results show good agreement between model simulation and experiment. Two frequency bandgaps are measured: 205–257 Hz and 587–639 Hz. Within these bandgaps, vibrations are completely attenuated. The level of vibration attenuation in the first bandgap is substantially larger than the level of vibration attenuation observed in the second bandgap. Mode shapes suggest that bending deformations experienced by the local resonators in the second bandgap are less than the deformations experienced in the first bandgap, and most vibrational energy is localized within the first bandgap where the fundamental resonant frequency is located, i.e., 224 Hz. The ability of the fabricated metamaterial structure to harvest electric power in these bandgaps is examined. Results show that vibration attenuation and energy harvesting characteristics of the metamaterial structure are coupled. Stronger vibration attenuation within the first bandgap has led to enhanced energy harvesting capabilities within this bandgap. Power measurements at optimum load resistance of 15 Ω reveal that maximum power generated within the first bandgap reaches 5.2 µW at 245 Hz. Compared with state-of-the-art, the metamaterial structure presented here shows a significant improvement in electric power generation, at considerably lower load resistance, while maintaining the ability to attenuate undesired vibrations within the frequency bandgap.
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Dong, Xingjian, Shuo Wang, Anshuai Wang, Liang Wang, Zhaozhan Zhang, Yuanhao Tie, Qingyu Lin, and Yongtao Sun. "Low-frequency bandgap and vibration suppression mechanism of a novel square hierarchical honeycomb metamaterial." Applied Mathematics and Mechanics 45, no. 10 (September 30, 2024): 1841–56. http://dx.doi.org/10.1007/s10483-024-3168-7.
Повний текст джерелаАнотація:
AbstractThe suppression of low-frequency vibration and noise has always been an important issue in a wide range of engineering applications. To address this concern, a novel square hierarchical honeycomb metamaterial capable of reducing low-frequency noise has been developed. By combining Bloch’s theorem with the finite element method, the band structure is calculated. Numerical results indicate that this metamaterial can produce multiple low-frequency bandgaps within 500 Hz, with a bandgap ratio exceeding 50%. The first bandgap spans from 169.57 Hz to 216.42 Hz. To reveal the formation mechanism of the bandgap, a vibrational mode analysis is performed. Numerical analysis demonstrates that the bandgap is attributed to the suppression of elastic wave propagation by the vibrations of the structure’s two protruding corners and overall expansion vibrations. Additionally, detailed parametric analyses are conducted to investigate the effect of θ, i.e., the angle between the protruding corner of the structure and the horizontal direction, on the band structures and the total effective bandgap width. It is found that reducing θ is conducive to obtaining lower frequency bandgaps. The propagation characteristics of elastic waves in the structure are explored by the group velocity, phase velocity, and wave propagation direction. Finally, the transmission characteristics of a finite periodic structure are investigated experimentally. The results indicate significant acceleration amplitude attenuation within the bandgap range, confirming the structure’s excellent low-frequency vibration suppression capability.
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Yang, Fan, Zhaoyang Ma, and Xingming Guo. "Bandgap characteristics analysis and graded design of a novel metamaterial for flexural wave suppression." Applied Mathematics and Mechanics 46, no. 1 (January 2025): 1–24. https://doi.org/10.1007/s10483-025-3204-7.
Повний текст джерелаАнотація:
AbstractA novel elastic metamaterial is proposed with the aim of achieving low-frequency broad bandgaps and bandgap regulation. The band structure of the proposed metamaterial is calculated based on the Floquet-Bloch theorem, and the boundary modes of each bandgap are analyzed to understand the effects of each component of the unit cell on the bandgap formation. It is found that the metamaterials with a low elastic modulus of ligaments can generate flexural wave bandgaps below 300 Hz. Multi-frequency vibrations can be suppressed through the selective manipulation of bandgaps. The dual-graded design of metamaterials that can significantly improve the bandgap width is proposed based on parametric studies. A new way that can regulate the bandgap is revealed by studying the graded elastic modulus in the substrate. The results demonstrate that the nonlinear gradient of the elastic modulus in the substrate offers better bandgap performance. Based on these analyses, the proposed elastic metamaterials can pave the way for multi-frequency vibration control, low-frequency bandgap broadening, and bandgap tuning.
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Hajhosseini, Mohammad. "Analysis of complete vibration bandgaps in a new periodic lattice model using the differential quadrature method." Journal of Vibration and Control 26, no. 19-20 (January 24, 2020): 1708–20. http://dx.doi.org/10.1177/1077546320902549.
Повний текст джерелаАнотація:
In this study, a new periodic lattice model with special vibration-absorbing properties is introduced. This periodic structure consists of the connected beam elements with circular cross-sections. Four models with different sets of cross-sectional radii are considered for this periodic lattice. The theoretical equations of longitudinal, torsional, and transverse vibrations of beams are solved using the combination of generalized differential quadrature and generalized differential quadrature rule methods to calculate the first three complete bandgaps. Investigating the effects of geometrical parameters on the bandgaps shows that all bands are close to each other for specific values of the cross-sectional radii. Having close bandgaps means that this periodic structure has a relatively wide bandgap in total. Furthermore, this wide band can move to low-frequency ranges by changing the lattice thickness. Absorbing both in-plane and out-of-plane vibrations over a wide bandgap at low-frequency ranges makes this periodic lattice a good vibration absorber. Verification of the analytical method using ANSYS software shows that the combination of generalized differential quadrature and generalized differential quadrature rule methods can be used for vibration analysis of two- or three-dimensional structures such as frames and trusses with high accuracy.
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Guo, Peng, and Qizheng Zhou. "An Analytical, Numerical, and Experimental Investigation on Transverse Vibrations of a Finite Locally Resonant Beam." Shock and Vibration 2022 (June 13, 2022): 1–17. http://dx.doi.org/10.1155/2022/6875718.
Повний текст джерелаАнотація:
An analytical, numerical, and experimental investigation on the transverse vibrations of a finite beam with periodically arrayed beam-like resonators was carried out. A continuous-discrete model of the finite locally resonant beam was established by employing the “mass-spring- mass” subsystem. The analytical solution of the coupling vibration equations was derived based on the modal superposition method, and the analytical expression of average velocity response and vibration transmissibility were given. Then, the minimum periodic number of different units which could result in a bandgap was determined. Finally, the bandgap of a finite locally resonant beam was confirmed by a vibration experiment on a simply supported beam with twelve uniformly distributed beam-like resonators. The numerical and experimental results show that finite locally resonant beams have low-frequency bandgaps like infinite locally resonant beams, and the bandgap position is close to the resonance frequency of resonators. In addition, for a beam with a different type of locally resonant units, the minimum number of units that can generate the bandgap is nearly the same. Within considered frequency ranges, the experimental results are consistent with the theoretical results, meaning that the transverse vibration in locally resonant beams could be substantially attenuated. The conclusions may be supported to the application of locally resonant theory to control low-frequency vibration and radiation noise.
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Muhammad, Shoaib, Shuai Wang, Fengming Li, and Chuanzeng Zhang. "Bandgap enhancement of periodic nonuniform metamaterial beams with inertial amplification mechanisms." Journal of Vibration and Control 26, no. 15-16 (January 14, 2020): 1309–18. http://dx.doi.org/10.1177/1077546319895630.
Повний текст джерелаАнотація:
The aim of this study was to obtain bandgaps that are much better, that is at lower frequencies and in broader frequency ranges. Novel nonuniform metamaterial beams with periodically variable cross sections and inertial amplification mechanisms are designed and investigated by numerical and experimental methods. Flexural vibration equations of the nonuniform metamaterial beams are established, and the enhanced bandgap and vibration reduction properties are achieved by combining Bragg scattering and the inertial amplification mechanisms. Numerical results of the bandgaps for the periodic elastic beams with and without the inertial amplification mechanisms are validated by comparing them with the results of vibration experiments. Effects of the amplification mass and angle on the bandgap properties are investigated. Larger amplification mass and angle lead to much enhanced bandgap performances of the nonuniform metamaterial beams in lower to higher frequency ranges.
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Wei, Wei, Feng Guan, and Xin Fang. "A low-frequency and broadband wave-insulating vibration isolator based on plate-shaped metastructures." Applied Mathematics and Mechanics 45, no. 7 (July 2024): 1171–88. http://dx.doi.org/10.1007/s10483-024-3160-6.
Повний текст джерелаАнотація:
AbstractA metamaterial vibration isolator, termed as wave-insulating isolator, is proposed, which preserves enough load-bearing capability and offers ultra-low and broad bandgaps for greatly enhanced wave insulation. It consists of plate-shaped metacells, whose symmetric and antisymmetric local resonant modes offer several low and broad mode bandgaps although the complete bandgap remains high and narrow. The bandgap mechanisms, vibration isolation properties, effects of key parameters, and robustness to complex conditions are clarified. As experimentally demonstrated, the wave-insulating isolator can improve the vibration insulation in the ranges of [50 Hz, 180 Hz] and [260 Hz, 400 Hz] by 15 dB and 25 dB, respectively, in contrast to the conventional isolator with the same first resonant frequency.
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Guo, Zhiwei, Buliang Xie, Meiping Sheng, and Hao Zeng. "Tunable Ultralow-Frequency Bandgaps Based on Locally Resonant Plate with Quasi-Zero-Stiffness Resonators." Applied Sciences 14, no. 4 (February 11, 2024): 1467. http://dx.doi.org/10.3390/app14041467.
Повний текст джерелаАнотація:
In order to suppress the transverse vibration of a plate, a quasi-zero-stiffness (QZS) resonator with tunable ultralow frequency bandgaps was introduced and analyzed. The resonator was designed by introducing the quasi-zero-stiffness systems into mass-in-mass resonators. The plane wave expansion method was employed to derive the bandgap characteristics of the locally resonant (LR) plate with QZS resonators, and corresponding simulations were carried out by finite element method (FEM). The results show that an LR plate with a QZS resonator can provide two bandgaps, and the ranges of the bandgaps agree well with the vibration attenuation bands calculated by FEM. Owing to the introduction of the QZS system, the bandgaps can be easily transferred to a lower frequency or even an ultralow frequency. The damping of the QZS resonators can effectively broaden the vibration attenuation bands. In addition, the differentiated design of the bandgap frequencies can be realized to obtain broadband low-frequency transverse wave suppression performance. Finally, a mechanical structure design scheme was proposed in order to achieve flexible adjustment of the bandgap frequency, which significantly increases the engineering applicability of QZS resonators.
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Yong, Jiawang, Wanting Li, Xiaojun Hu, Zhishuai Wan, Yiyao Dong, and Nenglian Feng. "Co-Design of Mechanical and Vibration Properties of a Star Polygon-Coupled Honeycomb Metamaterial." Applied Sciences 14, no. 3 (January 25, 2024): 1028. http://dx.doi.org/10.3390/app14031028.
Повний текст джерелаАнотація:
Based on the concept of component assembly, a novel star polygon-coupled honeycomb metamaterial, which achieves a collaborative improvement in load-bearing capacity and vibration suppression performance, is proposed based on a common polygonal structure. The compression simulation and experiment results show that the load-bearing capacity of the proposed metamaterial is three times more than that of the initial metamaterial. Additionally, metal pins are attached and particle damping is applied to the metamaterial to regulate its bandgap properties; the influence of configuration parameters, including the size, number, position, and material of the metal pins, on bandgaps is also investigated. The results show that the bandgap of the proposed metamaterial can be conveniently and effectively regulated by adjusting the parameters and can effectively suppress vibrations in the corresponding frequency band. Particle damping can be used to continuously adjust the frequency of the bandgap and further enhance the vibration suppression capacity of the metamaterial in other frequency bands. This paper provides a reference for the design and optimization of metamaterials.
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Han, Wenwen, and Shui Wan. "Flexural Wave Bandgaps in a Prestressed Multisupported Timoshenko Beam with Periodic Inerter-Based Dynamic Vibration Absorbers." Sustainability 15, no. 4 (February 16, 2023): 3680. http://dx.doi.org/10.3390/su15043680.
Повний текст джерелаАнотація:
Locally resonant (LR) metamaterial structures possess bandgaps in which wave propagation is significantly attenuated. In this paper, we discuss flexural wave bandgaps in an LR beam subjected to a global axial force and multiple vertical elastic supports. An array of inerter-based dynamic vibration absorbers (IDVAs) was periodically attached to the LR beam. The flexural wave band structure of this prestressed multisupported LR beam was first derived using the transfer matrix method (TMM) and then explicitly illustrated through a numerical example. Four bandgaps were identified: a bandgap located in the low-frequency zone, a Bragg band generated by Bragg scattering, and two LR bands generated by the local resonance of the IDVAs. The effects of the IDVA parameters, axial force, and vertical elastic support on the properties of the bandgaps were evaluated. In particular, the bandgaps merged accompanied by an exchange of their edge frequencies. The bandwidth of the merged bandgap was nearly equal to the sum of the bandwidths of the bandgaps involved, indicating a method for controlling broadband flexural vibration through the bandgap splicing mechanism.
Дисертації з теми "Vibration bandgap"
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Zhang, Runze. "Modeling of coupled vibration systems with fluid-structure interaction." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPAST136.
Повний текст джерелаАнотація:
Cette thèse porte sur deux aspects de la dynamique vibratoire des structures en interaction fluide-structure (IFS) : le contrôle des vibrations des structures immergées dans un fluide et la récupération des vibrations induites par un fluide pour leur conversion en énergie électrique. Ce mémoire présente nos contributions dans ces deux domaines.Premièrement, concernant le contrôle des vibrations, l'émergence récente des méta-structures a ouvert de nouvelles perspectives pour maîtriser les vibrations des structures en IFS. Ces structures, souvent constituées de microstructures périodiques, permettent de moduler la propagation des ondes vibratoires. Leur conception, prenant en compte les conditions spécifiques à l'IFS, constitue un sujet de grande importance. Nous avons développé un modèle par éléments finis basé sur l'analyse d'une cellule élémentaire, qui permet de prédire les bandes de fréquences interdites pour des plaques composites périodiques soumises aux conditions IFS. Une contribution clé de ce travail réside dans la formulation d'une nouvelle matrice de masse ajoutée, intégrant les conditions de Bloch dans les domaines solide et fluide de la cellule élémentaire. Cette approche permet un contrôle passif des vibrations et la conception de structures minces avec des bandes de fréquences spécifiques.Ensuite, nous avons exploré la modulation active de ces bandes de fréquences dans des scénarios similaires de structures minces avec IFS, en introduisant un système couplé comprenant des composants piézoélectriques. Le modèle de cellule élémentaire fluide-structure, tenant compte des conditions de Bloch, inclut également les effets de couplage piézoélectrique. Nos recherches montrent que les effets inertiels du fluide influencent fortement les bandes de fréquences des structures minces, en raison de leur faible inertie propre. Une optimisation de la microstructure, incluant la disposition et la forme des composants piézoélectriques, ainsi que la définition d'une loi de contrôle, permet d'obtenir une modulation optimale des bandes de fréquences, en fonction des applications spécifiques.Dans la seconde partie du travail, nous avons étudié les vibrations induites par un écoulement fluide comme source d'énergie, pouvant être convertie en électricité grâce à l'effet piézoélectrique direct. Un système couplé, composé d'une structure vibrante intégrant des composants piézoélectriques connectés à un circuit externe, a été modélisé pour être soumis à un écoulement fluide. Contrairement aux modèles simplifiés de type poutre souvent utilisés, nous avons proposé un modèle à échelle complète basé sur des éléments finis solides. Cela permet de prendre en compte des caractéristiques complexes, telles que l'utilisation de transducteurs microstructurés et de cantilevers non uniformes. À l'aide de ce modèle, diverses configurations de systèmes de récupération d'énergie avec générateurs de turbulence, permettant une efficacité améliorée, ont été étudiées.En résumé, la modélisation multiphysique du couplage pour différentes conditions d'IFS proposée dans cette étude, permet non seulement de prédire et de contrôler efficacement les vibrations structurelles en milieu fluide, mais elle offre également des outils numériques pour le développement de systèmes de récupération d'énergie piézoélectrique performantsThis thesis addresses two key aspects of the vibrational dynamics of structures with fluid-structure interaction (FSI): the control of vibrations in structures immersed in a fluid and the conversion of fluid-induced vibrations into electrical energy. This dissertation presents our contributions to these two domains. To this end, the study first proposes an unit cell-based finite element model to predict vibration bandgaps in periodic composite plates under FSI conditions. By introducing a novel fluid-added mass matrix integrating Bloch boundary conditions, the fluid's inertial effects are incorporated into the bandgap analysis, enabling designing for vibration control in periodic plates submerged in liquids, achieving passive control.Based on this foundation, the research further explores the potential for actively tuning the vibration bandgaps of periodic composite plates submerged in liquids, which integrate connected piezoelectric sensors and actuators with feedback control. Therefore, an unit cell-based vibration bandgap tuning model with inertial fluid is developed, which integrates Bloch boundary conditions for both fluid and piezoelectric coupled solid domains. Then, the study reveals that in liquid environments, the fluid-added mass effect significantly impacts the bandgap characteristics of thin-walled structures, reducing the effectiveness of control strategy. Increasing the structure's self inertia or optimizing the arrangement of piezoelectric patches can mitigate this effect.On the other hand, the rivers and oceans are in constant motion, containing substantial kinetic energy. When fluid flows over a structural surface, the induced structural vibrations can be viewed as a potential source of clean and renewable energy. By utilizing the direct piezoelectric effect of piezoelectric materials, the kinetic energy of the fluid can be converted into usable electrical energy, enabling fluid energy harvesting. However, in such energy harvesting systems, significant FSI and electro-mechanical coupling effects are often accompanied by complex nonlinear dynamic behavior. The presence of these coupling effects complicates numerical simulations in this field, making it challenging, especially when considering practical applications where a deep understanding of these nonlinear behaviors and their impact on system performance is essential. Therefore, this thesis develops a full-scale finite element model to capture the strong local FSI behavior of complex thin-walled piezoelectric fluid energy harvesters (PFEH) involving microstructured transducers and non-uniform cantilevers, which are often ignored by simplified models. The research analyzes different energy harvester designs through numerical simulations, examining the influence of substrate cross-sectional shape, piezoelectric patch arrangement, and microstructure on the system's dynamic response and energy output efficiency.Finally, the study further enhance the power output of PFEHs using synergistic vortex generators composed of upstream double plates and downstream cylinder with a small spacing in dynamic water environments. With the synergistic effects of multi vortex generators, it is possible to achieve higher frequency and stable larger amplitude vibrations for the piezoelectric flag, thereby obtaining higher energy harvesting efficiency. Overall, the multi-physics coupling modeling for different FSI conditions proposed in this study not only effectively predict and control structural vibrations in fluid environments but also provide a theoretical foundation and technical support for the development of efficient piezoelectric energy harvesting systems
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Rodrigues, Cunha Leandro. "Robust bandgaps for vibration control in periodic structures." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD060.
Повний текст джерелаАнотація:
Dans cette thèse, une méthodologie simple pour trouver des bandes interdites robustes est présentée. Quatre cellules unitaires différentes sont utilisées comme exemples numériques pour des modèles infinis et finis. Les deux premiers sont liés aux zones d'atténuation créées pour les ondes longitudinales en utilisant des cellules unitaires de masse et ressort et de barres. La méthode Matrice de Transfert est utilisée pour modéliser la cellule unitaire. Avec cette méthode, il est possible d'obtenir les réponses en fréquence, en utilisant une méthode spectrale, et des constantes de dispersion, en résolvant un problème a valeur propre. Les paramètres physiques et géométriques les plus influents sont déterminés en effectuant une analyse de sensibilité aux dérivées partielles et aux différences finies à travers un modèle infini. Dans ce cas, pour le deuxième exemple, la section de la demi-cellule est considérée comme une variable stochastique, représentée par une fonction densité de probabilité pour une analyse probabiliste. Le troisième exemple concerne les bandes interdites pour les ondes de flexion utilisant des cellules unitaires de poutres. Dans ce cas, la méthode habituelle de Matrice de Transfert ne peut pas être utilisée pour obtenir une réponse de structures finies en basse fréquence en raison de la présence de matrices mal conditionnées. Par conséquent, une méthode récursive est utilisée pour éviter la multiplication de matrices. Une analyse expérimentale est également réalisée pour ce cas, mais considérant que la longueur de la moitié des cellules unitaire comme incertaine. Le dernier exemple est un treillis périodique considérée avec et sans propriétés intelligentes. La cellule unitaire de cette structure en treillis peut avoir des membres passifs et actifs. À cause de la complexité de ce type de cellule, la méthode des éléments finis est utilisée. Cependant, ce type de structure ne présente pas de ruptures d'impédance suffisamment fortes pour ouvrir des bandes interdites même avec la présence de sous-structures répétitives. En vertu de cela, huit scénarios sont étudiés en considérant l'introduction de masse concentrée dans les articulations et les actionneurs piézoélectriques dans les circuits shunt résonants qui sont considérés comme stochastiques pour des cas spécifiques. À la fin, les résonances internes sont analysées à l'aide d'un modèle plus précis. Pour chaque modèle de structure, une simulation de Monte Carlo avec Latin Hypercube est effectuée, les distinctions entre les zones d'atténuation incertaines correspondantes pour les modèles finis et infinis sont exposées et la relation avec les modes localisés est clarifiée. Ces résultats suggèrent que les modèles finis ont une bande interdite plus large que les modèles infinis en considérant les incertitudes. En d'autres termes, les incertitudes entre les cellules voisines se compensent et les structures finies sont naturellement plus robustes. Enfin, l'effet de l'augmentation du niveau d'incertitude, en faisant varier un coefficient stochastique, est analysé et le concept de bande interdite robuste est présentéIn this thesis, a simple methodology to find robust bandgaps is presented. Four different periodic structures are used as numerical examples for infinite and finite models. The first two are related to attenuation zones created for longitudinal waves using spring-mass and stepped rod unit cells. The Transfer Matrix method is used to model the unit cell. With this method, it is possible to obtain the frequency responses, using a spectral method, and dispersion constants, solving an eigenvalue prob-lem. The most influential physical and geometrical parameters are determined by performing partial derivative and finite difference sensitivity analysis through an infinite model. Therein, for the second example, the cross-section area of half-cell is considered as a stochastic variable represented by a probability density function with specific deviation properties for a probabilistic analysis. The third example concerns the bandgaps for flexural waves using stepped beams unit cells. For this case, the classical Transfer Matrix method cannot be used to obtain finite structures response in low frequency because of the presence of ill-conditioned matrices. Therefore, a recursive method termed Translation Matrix, which avoid matrix multiplication, is used and the corresponding probabilistic analysis is per-formed using the half-cell thickness as a random variable. An experimental analysis is also performed for this case, but considering half-cell length as uncertain. The last example is a periodic truss that is considered with and without smart components. The unit cell of this lattice structure can present pas-sive and active members. As long as the type of unit cell is more complex, the finite element method is used. However, this kind of structure does not have impedance mismatches strong enough to open bandgaps although the presence of repetitive substructures. In virtue of this, eight scenarios are inves-tigated considering the introduction of concentrated mass on joints and piezoelectric actuators in reso-nant shunt circuit which are considered as stochastic for specific cases. For each structure model, a Monte Carlo Simulation with Latin Hypercube sampling is carried out, the distinctions between the corresponding uncertain attenuation zones for finite and infinite models are exposed and the relation with localized modes is clarified. These results lead to conclude that the finite models present a larger stop zone considering stochastic parameters than infinite models. In other words, the uncertainties be-tween neighbors’ cells compensate each other and the finite structures is naturally more robust. Final-ly, the effect of increasing the uncertainty level, by varying a stochastic coefficient, is analyzed and the concept of robust band gap is presented
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Zheng, Xuqian. "Ultra-Wide Bandgap Crystals for Resonant Nanoelectromechanical Systems (NEMS)." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1554765522327938.
Повний текст джерела
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Pyskir, Adrien. "Application de métamatériaux aux problématiques vibroacoustiques automobiles." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEC011.
Повний текст джерелаАнотація:
Les métamatériaux sont des matériaux architecturés de telle sorte qu’ils présentent des propriétés exotiques, issues non pas du matériau constitutif, mais de leur structure interne. Bien qu’ayant été étudiés depuis une vingtaine d’années, peu d’applications réelles ont été recensées, notamment dans le domaine industriel. Cette thèse est consacrée aux métamatériaux élastiques susceptibles de réduire les vibrations dans les véhicules automobiles. En effet, une meilleure isolation des principales sources vibratoires permettrait l’amélioration du confort vibratoire et la durée de vie des pièces mécaniques. Les résultats de calculs numériques et essais expérimentaux montrent que les métamatériaux peuvent satisfaire des contraintes contradictoires, et représentent donc des candidats intéressants pour la réalisation d’innovations industrielles. Ce type de solutions étant fondamentalement différent des systèmes d’isolation actuels, le premier chapitre dresse un état de l’art des métamatériaux, afin d’en comprendre les mécanismes et les méthodes numériques permettant d’en calculer les performances. Le deuxième chapitre aborde les techniques de caractérisation des matériaux employées pendant cette thèse. Les essais mécaniques ainsi que les résultats permettent de définir les modèles matériaux utilisés par la suite. Dans le troisième chapitre, des calculs numériques appliqués à différentes architectures aident à mieux comprendre certains mécanismes des métamatériaux et à choisir le meilleur candidat vis-à-vis des propriétés ciblées. Celui-ci est approfondi dans le quatrième chapitre, à travers des études paramétriques statiques et dynamiques. Des propositions d’améliorations géométriques sont proposées, y compris un métamatériau hybride aux propriétés supérieures. Afin de vérifier les résultats expérimentaux et d’acquérir une meilleure compréhension des mécanismes sous-jacents, le cinquième chapitre aborde finalement les essais expérimentaux effectués, l’analyse de leurs résultats, et leur confrontation avec les résultats numériquesMetamaterials are architectured materials exhibiting exotic properties due to their internal stucture rather than their constitutive material. They have now been studied for two decades, but have yet to make their mark outside laboratories, especially for industrial applications. This thesis focuses on elastic metamaterials that can contribute to fix vibration issues in the automotive field. Better isolation of the main vibration sources would increase both the vibroacoustic comfort in the vehicles and the safety of mechanical parts. Through computations and experimentations, it is shown that metamaterials can be designed to meet different criteria usually contradictory and as such, are strong candidates for innovative breakthroughs in industry. As this kind of solutions differs radically from existing ones, the first chapter is a state-of-the-art review, both to grasp the main mechanims behind the multitude of metamaterials designs that can be found in the literature, as well as the methods used to modelize them. The second chapter tackles the characterization of the materials used along this thesis. The mechanical tests and results presented allow to determine the material models then inserted in the computations. Through preliminary computations, the third chapter attempts to understand and select the most promising mechanisms to satisfy the expected specifications. The chosen design properties are further investigated in the fourth chapter, through static and dynamic computations, as well as parametric studies. A hybrid metamaterial with enhanced isolation properties is proposed. To finally assess the numerical results obtained and reach better undestanding of the underlying mechanisms, the fifth chapter deals with the performed experimental tests, their analysis, and their comparison with previous results
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Moreira, Fernando Jose de Oliveira. "Um controlador H 'infinito' alfa de Banda limitada para o controle ativo de vibração estrutural." [s.n.], 1998. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263222.
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Orientador: Jose Roberto de França ArrudaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Neste trabalho é apresentada uma metodologia para controle ativo de vibração. O objetivo é amortecer modos de vibração de uma estrutura na região de média freqüência. A técnica empregada envolve controle por realimentação e se aplica tanto a problemas de controle de estruturas flexíveis como controle ativo de vibração e ruído. O enfoque proposto é o de controle robusto utilizando a teoria 'H IND. INFINITO¿. Desta forma, inserem-se no projeto características de robustez à dinâmica não modelada devido ao truncamento do modelo do sistema estrutural. Também estão presentes no projeto critérios de robustez à variação nos parâmetros da dinâmica do sistema. O resultado é um controlador de baixa ordem de fácil implementação que produz um eficiente amortecimento nos modos a serem controlados, sem alterar a dinâmica dos demais modos da estrutura. Dois exemplos experimentais são apresentados, comprovando a exeqüibilidade do projeto
Abstract: This work presents a new approach for the active control of structural vibration. The main goal is to damp some of the structural modes in the mid-frequency range. The feedback control strategy used in this work can be applied either to the control of flexible structures or to the control of vibration and noise. It consists of an 'H IND. INFINITE¿ controller which is robust to unmodeled residual uncertainty due to model truncation of the structural system. AIso, a parametric robustness requirement, due to parameter variations of the system dynamics, is included in the designo Only the damping of the modes to be controlled is modified, while the other ones are kept unchanged. Two experimental examples are shown to demonstrate that the practical implementation of the proposed controller is feasible
Doutorado
Mecanica dos Sólidos e Projeto Mecanico
Doutor em Engenharia Mecânica
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Gehring, Junior Waldemar [UNESP]. "Monitoramento da deflexão de serras de fita contínua como proposta de avaliação da qualidade de peças serradas de madeira." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/144189.
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Dans le sciage continu de bois effectué avec une scie à ruban, la conception de l'outil de coupe, l'usure et les dommages dus à l'utilisation de cet outil dans le processus de production modifient le comportement de la lame sur un cycle d'utilisation, la rendant plus ou moins instable jusqu'à perdre sa stabilité, ce qui va générer des produits sciés de mauvaise qualité. Considérer cette tendance tout au long de la vie de la scie ou de son application dans une période donnée dans des conditions réelles de coupe permet d'évaluer et projeter la scie ainsi que sa durabilité. Pour cela, la conception d'un dispositif robuste, résistant aux vibrations, aux environnements agressifs, à la saleté, tout en ayant une bonne capacité de stockage de l'information est primordiale. Le but de cette étude est de proposer un dispositif d'enregistrement de données pour surveiller l'instabilité et vibration de l'outil de coupe dans le processus de sciage du bois par scie à ruban en continu. A partir de ce scénario, les éléments du projet d'outil de coupe ont été étudiés avec pour bases l'usinage du bois, le projet de l'outil de coupe, sa géométrie et ses conséquences comme la vibration, la stabilité et l'usure. Un prototype à l'échelle de laboratoire a validé le système du préprojet et la construction de l'acquisition de données. Nous avons choisi d'utiliser le microcontrôleur Arduino qui fournit des logiciels libres de programmation permettant au système d'être fabriqué à faible coût. Dans une deuxième étape, ce mécanisme de contrôle a été appliqué à un environnement industriel de l'industrie de première transformation du bois où il peut être utilisé comme support pour l'évaluation du processus de coupe. Le dispositif s'est avéré être robuste et opérationnel dans des conditions réelles de production dans une scierie industrielle de grande envergure. Cet présent article décrit le capteur utilisé, le microcontrôleur, sa programmation et confirme qu 'avec ce dispositif de surveillance il est possible d'enregistrer les tendances de la déviation de l'outil de coupe dans le sciage du bois par scie à ruban et mesurer indirectement la qualité des pièces sciées et de la capacité du process sciage.
No serramento contínuo da madeira por serra de fita, o projeto da ferramenta de corte, o desgaste e as avarias do uso destas ferramentas no processo de produção fazem com que o comportamento da lâmina ao longo de um ciclo de uso seja mais ou menos instável, podendo perder estabilidade e impactando em produtos mal serrados. Conhecer essa tendência ao longo de toda a vida útil da serra ou mesmo a sua aplicação em dado período em condições reais de corte permite avaliar o projeto da serra e sua durabilidade. Para isso, o projeto de um dispositivo robusto, resistente a vibração e a ambientes severos e sujos, além de boa capacidade de armazenamento de informações é de grande valia. O objetivo do presente trabalho foi propor um dispositivo de registro de dados para monitorar a instabilidade/vibração da ferramenta de corte no processo de serramento da madeira por serra de fita. Com vistas a essas premissas foram estudados os elementos para o projeto da ferramenta de corte e as referências sobre os fundamentos da usinagem da madeira, o projeto da ferramenta de corte, sua geometria e causas para as decorrências como a vibração, estabilidade e desgaste. Foi construído um protótipo em escala laboratorial, onde foi validado o pré-projeto e o sistema de aquisição de dados. Optou-se pelo uso do microcontrolador Arduino que disponibiliza software livre para sua programação permitindo que o sistema possa ser reproduzido a baixo custo. Em um segundo estágio este mecanismo de controle foi expandido para um ambiente industrial madeireiro onde pôde ser utilizado como apoio para a avaliação do processo de corte. O dispositivo mostrou-se robusto e operacional em condições reais de produção em um serraria de grande porte. O presente trabalho relata o sensor usado, o microcontrolador, sua programação e afirma que por meio do monitoramento da deflexão da serra de fita é possível registrar as tendências da deflexão da ferramenta de corte em operações de serramento da madeira por serra de fita e indiretamente medir a qualidade da madeira serrada e a capabilidade do processo.
In continuous sawing wood by a large Bandsaw the cutting tool design, use and tools faults in the production process causes blade behavior over a duty cycle. The process looses stability and impacts in badly sawn products. Knowing this trend throughout the life of the blade or its application in a given period on real conditions of cut allows evaluating the project and the durability of the saw. For this, the design of a robust device, resistant to vibration, harsh and dirty environments and good information storage capacity is a big deal. The aim of this study was to propose a data recording device to monitor the instability / vibration of the cutting tool in Bandsawing process of the wood. With a view to these assumptions were studied elements for cutting tool design and references about the fundaments of wood machining, cutting tool design, geometry and the causes that origin vibration, instability and tools wear. A prototype in laboratory scale which has validated the pre-design and data acquisition system was built. We chose to use the Arduino microcontroller that provides free software to its programming allowing the system to be reproduced at low cost too. In a second stage this control mechanism has been expanded to a timber industrial environment where it might be used as support for the evaluation of the cutting process. The device proved to be robust and operational in real production conditions in a large sawmill. This paper reports the used sensor, microcontroller, its programming and states that by monitoring the bandsaw deflection is possible to record the trends of the cutting tool instability in sawing operations of wood by bandsaw and indirectly measure quality lumber and capability of the process.
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Ratnaparkhe, Amol. "FIRST PRINCIPLES STUDY OF ELECTRONIC ANDVIBRATIONAL PROPERTIES OF WIDE BAND GAPOXIDE AND NITRIDE SEMICONDUCTORS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1619606222502271.
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Tsai, Meng-Huang, and 蔡孟皇. "Structural analysis and vibration control of high-speed bandsaw." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/hgg5n6.
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碩士國立虎尾科技大學
創意工程與精密科技研究所
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This study is focuses on structural analysis of band saw machine and vibration control, used of finite element analysis and transient response of the experimental results, find out the band saw machine vibration prone structure, reuse, reduce the size of the change to identify the direction of vibration . This article struck by the static experimental results, the hit points from many different experiments, the transient response behavior occurs in a specific number of frequencies, while the higher frequency of double column is likely to cause the hydraulic structure of excitation. Then re-use finite element software Ansys Workbench simulation and actual experimental data with each other than its accuracy, Modal response analysis from the three parts also show that in the two-pillar structure of hydraulic pressure is unstable, easily cutting band saw machine is stable and not easily able to create the structure of the resonance states appear in the frequency will affect the cutting of the response, its frequency is easier to influence the occurrence of vibration of cutting elements. The finite element simulation results can be obtained in three different forms of structural modifications, the same length and width of the rectangle to change the frequency on the H group of the lowest vibration characteristics to simulate the three-part analysis of the structural comparison, and know the most H-type pattern for the length of the structure to change the width of the rectangle, this structure forms a more effective in reducing the vibration of the structure in the cutting, because the Y axis of this structure is reinforced structure, it can determine that some of them might in the Y-axis is caused by the vibration of the main reasons for the impact, however, modify the size of the differences after the resonance is not, but could be back from that direction can be modified for the domestic stability of band sawing machine designed to provide objective basis.
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(6532391), Nicolas Guarin-Zapata. "Modeling and Analysis of Wave and Damaging Phenomena in Biological and Bioinspired Materials." Thesis, 2021.
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There is a current interest in exploring novel microstructural architectures that take advantage of the response of independent phases. Current guidelines in materials design are not just based on changing the properties of the different phases but also on modifying its base architecture. Hence, the mechanical behavior of composite materials can be adjusted by designing microstructures that alternate stiff and flexible constituents, combined with well-designed architectures. One source of inspiration to achieve these designs is Nature, where biologically mineralized composites can be taken as an example for the design of next-generation structural materials due to their low density, high-strength, and toughness currently unmatched by engineering technologies.
The present work focuses on the modeling of biologically inspired composites, where the source of inspiration is the dactyl club of the Stomatopod. Particularly, we built computational models for different regions of the dactyl club, namely: periodic and impact regions. Thus, this research aimed to analyze the effect of microstructure present in the impact and periodic regions in the impact resistance associated with the materials present in the appendage of stomatopods. The main contributions of this work are twofold. First, we built a model that helped to study wave propagation in the periodic region. This helped to identify possible bandgaps and their influence on the wave propagation through the material. Later on, we extended what we learned from this material to study the bandgap tuning in bioinspired composites. Second, we helped to unveil new microstructural features in the impact region of the dactyl club. Specifically, the sinusoidally helicoidal composite and bicontinuous particulate layer. For these, structural features we developed finite element models to understand their mechanical behavior.
The results in this work help to elucidate some new microstructures and present some guidelines in the design of architectured materials. By combining the current synthesis and advanced manufacturing methods with design elements from these biological structures we can realize potential blueprints for a new generation of advanced materials with a broad range of applications. Some of the possible applications include impact- and vibration-resistant coatings for buildings, body armors, aircraft, and automobiles, as well as in abrasion- and impact-resistant wind turbines.
Частини книг з теми "Vibration bandgap"
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Yuan, Weiting, and Qibo Mao. "Experimental Study of Bending Vibration Bandgaps for an Acoustic Metamaterial Beam." In Lecture Notes in Mechanical Engineering, 272–78. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-8864-8_26.
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Deng, Jie. "Low-frequency bandgaps by topological acoustic black holes." In Phonons - Recent Advances, New Perspectives and Applications [Working Title]. IntechOpen, 2024. http://dx.doi.org/10.5772/intechopen.1005765.
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Nowadays, acoustic black holes (ABHs) are very popular for producing efficient vibration reduction at high frequencies in combination with some damping mechanisms. However, its low-frequency performance is hard to improve since the ABH effect principally occurs beyond its cut-on frequency. Fortunately, periodic ABH configuration offers some bandgaps below that frequency for wave attenuation. In this chapter, a topological ABH structure is suggested to produce a new bandgap at very low frequencies, by taking a supercell and decreasing the ABH distance. The wave and Rayleigh-Ritz method (WRRM) is adopted to compute the complex dispersion curves. Examinations of the dispersion curves and transmissibilities confirm the efficiency of the low-frequency vibration reduction capability of the proposed topological ABHs.
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Sahu, Rajesh, S. K. Jain, and Balram Tripathi. "A Comparative Study on Visible Light Induced Photocatalytic Activity of MWCNTs Decorated Sulfide Based (ZnS & CdS) Nano Photocatalysts." In Advanced Materials and Nano Systems: Theory and Experiment - Part 2, 179–98. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815049961122020013.
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Sulfide-based semiconductor nano photocatalysts like ZnS and CdS of different particle sizes were prepared by chemical method. These photo catalysts show an excellent photo catalytic activity in the visible region due to their appropriate energy bandgap (Eg). Multiwalled carbon nanotubes (MWCNTs) intercalated sulfide-based photocatalysts like ZnS/MWCNTs and CdS/MWCNTs composites enhance photocatalytic response in comparison to ZnS and CdS NCs. The photocatalytic activity of MWCNTs intercalated ZnS and CdS composites were studied via decomposition of organic pollutant. The obtained particle size of the CdS, ZnS, MWNT/CdS, and MWCNT/ZnS crystals were found to be 32.0 nm, 8.48 nm, 38.5 nm, and 13.18 nm, respectively. The FTIR characteristics of MWCNT/ZnS and MWCNT/CdS composites represent bands at 1637 and 3313 cm-1 in presence of methylene blue. The intense band at 1637 cm-1 could be the stretching vibrations of the C=O group and the other intense band at 3313cm-1 was assigned to the stretching vibration of O-H group. The reduction in optical band gap for MWCNTs/CdS (2.39eV) over CdS (2.44eV) and MWCNT/ZnS (3.77 eV) over ZnS (3.88 eV) was observed. Enhancement in photocatalytic activity was verified along with pseudo-first-order chemical kinetics.
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Khalid, S. "Advanced Electric Propulsion Systems for Hybrid Electric Vehicles." In Advances in Mechatronics and Mechanical Engineering, 1–54. IGI Global, 2024. https://doi.org/10.4018/979-8-3693-5797-2.ch001.
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This chapter explores advanced electric propulsion systems for hybrid electric vehicles (HEVs), focusing on design, control, and performance optimization. It examines key components including electric motors, power electronics, and energy storage systems, discussing their selection and integration. The chapter reviews control strategies such as field-oriented control, direct torque control, and model predictive control, highlighting their advantages and limitations. Performance optimization techniques using finite element analysis, computational fluid dynamics, and optimization algorithms are explored. The integration of renewable energy sources and vibration analysis and mitigation strategies are addressed. The chapter also discusses future trends, including emerging technologies like wide bandgap semiconductors and high-temperature superconductors, and the potential of artificial intelligence in system optimization. Through case studies and simulation results, the chapter provides a comprehensive overview of the state-of-the-art in HEV propulsion systems.
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Thomas, Michael E. "Optical Propagation in Solids." In Optical Propagation in Linear Media. Oxford University Press, 2006. http://dx.doi.org/10.1093/oso/9780195091618.003.0013.
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This chapter emphasizes the linear optical properties of solids as a function of frequency and temperature. Such information is basic to understanding the performance of optical fibers, lenses, dielectric and metallic mirrors, window materials, thin films, and solid-state photonic devices in general. Optical properties are comprehensively covered in terms of mathematical models of the complex index of refraction based on those discussed in Chapters 4 and 5. Parameters for these models are listed in Appendix 4. A general review of solid-state properties precedes this development because the choice of an optical material requires consideration of thermal, mechanical, chemical, and physical properties as well. This section introduces the classification of optical materials and surveys other material properties that must be considered as part of total optical system design involving solidstate optics. Solid-state materials can be classified in several ways. The following are relevant to optical materials. Three general classes of solids are insulators, semiconductors, and metals. Insulators and semiconductors are used in a variety of ways, such as lenses, windows materials, fibers, and thin films. Semiconductors are used in electrooptic devices and optical detectors. Metals are used as reflectors and high-pass filters in the ultraviolet. This type of classification is a function of the material’s electronic bandgap. Materials with a large room-temperature bandgap (Eg > 3eV) are insulators. Materials with bandgaps between 0 and 3 eV are semiconductors. Metals have no observable bandgap because the conduction and valence bands overlap. Optical properties change drastically from below the bandgap, where the medium is transparent, to above the bandgap, where the medium is highly reflective and opaque. Thus, knowledge of its location is important. Appendix 4 lists the bandgaps of a wide variety of optical materials. To characterize a medium within the region of transparency requires an understanding of the mechanisms of low-level absorption and scattering. These mechanisms are classified as intrinsic or extrinsic. Intrinsic properties are the fundamental properties of a perfect material, caused by lattice vibrations, electronic transitions, and so on, of the atoms composing the material.
Тези доповідей конференцій з теми "Vibration bandgap"
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Singhapurage, Helani A. S., Dinusha M. Senarathna, Jeremy Sylvester, Chandra P. Neupane, and F. Ganikhanov. "Ultrafast Coherent Raman Study of Lattice Vibration Dynamics in Wide-bandgap Semiconductors." In CLEO: Applications and Technology, JTu2A.127. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/cleo_at.2024.jtu2a.127.
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Optical phonon dynamics, including decay of symmetry forbidden modes, have been studied in technologically important wide-bandgap semiconductors. Phonon decay times for LO-and TO- phonon modes have been found to be within 0.82-1.56 ps and are explained in terms of parametric phonon interactions.
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Anigbogu, Winner, and Hamzeh Bardaweel. "Concurrent Passive Broadband Vibration Suppression and Energy Harvesting Using a Dual-Purpose Magnetoelastic Metamaterial Structure: Experimental Validation and Modeling." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-67652.
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Abstract A dual-purpose metamaterial structure that can concurrently suppress vibrations and scavenge energy is presented. The metamaterial assembly presented in this work uses a permanent magnet-coil system in addition to an elastic cantilever beam to perform its dual functions. A prototype is manufactured and a COMSOL model is developed. Two bandgaps are observed at 205–257 Hz and 587–639 Hz. COMSOL simulations show excellent agreement with measured data. Within these bandgaps the structure blocks vibrations from traveling through and, simultaneously, converts vibrations into electric power. The first bandgap has a vibration attenuation level larger than the attenuation level observed in the second bandgap. Mode shapes reveal that the local resonators experience larger deformations in the first bandgap than in the second bandgap and the vibrational energy is mostly contained within the first bandgap where the resonant frequency occurs, i.e., 224 Hz. The ability of the metamaterial assembly to scavenge these vibrations while simultaneously suppressing them is demonstrated. At an optimum load resistance of 15 Ω, within the first bandgap, approximately 2.5 μW was generated, while 0.6 nW was measured within the second bandgap. At optimum load resistance, measurements show maximum electric power reaching 5.2 μW within the first bandgap.
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Chavan, Shantanu, and Vijaya V. N. Sriram Malladi. "Programmable Bandgaps in Meta-Structures With Dynamic Vibration Resonators." In ASME 2023 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/smasis2023-112818.
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Abstract Elastic wave propagation is controlled using meta-structures with dynamic vibration resonators (DVRs). These meta-structures exhibit bandgaps whose location is determined by the attributes of the DVRs, especially their resonant frequency. However, in passive meta-structures, the bandgap location is fixed, which limits their ability to attenuate vibrations over a wide frequency range. To overcome this limitation, this study introduces a novel approach to achieve a wide programmable bandgap using a DVR with two states: high-frequency and low-frequency states. A new n-bit nomenclature for the meta-structure is introduced to absorb vibrations over a wide frequency bandwidth by switching between various n-bit configurations. The programmability of these meta-structures is assessed, and the results are validated with experiments. This novel approach allows for a wide programmable bandgap, which significantly improves the effectiveness of meta-structures in attenuating vibrations and acoustics over a broad frequency range. In conclusion, this study presents a new approach to achieving programmable bandgap meta-structures with dynamic vibration resonators, which can significantly improve their ability to mitigate vibrations and sound in various applications, including transportation, buildings, and machinery. This innovation has the potential to address several engineering challenges and contribute to the development of more efficient and effective NVH systems.
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Sugino, Christopher, Stephen Leadenham, Massimo Ruzzene, and Alper Erturk. "Modal Analysis of Bandgap Formation for Vibration Attenuation in Locally Resonant Finite Beams." In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-60552.
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Metamaterials made from locally resonating arrays can exhibit attenuation bandgaps at wavelengths much longer than the lattice size, enabling low-frequency vibration attenuation. For an effective use of such locally resonant metamaterial concepts, it is required to bridge the gap between the dispersion characteristics and modal behavior of the host structure with its resonators. To this end, we develop a novel argument for bandgap formation in finite-length beams, relying on modal analysis and the assumption of infinitely many resonators. This assumption is analogous to the wave assumption of an infinitely long beam composed of unit cells, but gives additional analytical insight into the bandgap, and yields a simple formula for the frequency range of the bandgap. We present a design guideline to place the bandgap for a finite beam with arbitrary boundary conditions in a desired frequency range that depends only on the total mass ratio and natural frequency of the resonators. For a beam with a finite number of resonators and specified boundary conditions, we suggest a method for choosing the optimal number of resonators. We validate the model with both finite-element simulations and a simple experiment, and draw conclusions.
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LeGrande, Joshua, Mohammad Bukhari, and Oumar Barry. "Topological Properties and Localized Vibration Modes in Quasiperiodic Metamaterials With Electromechanical Local Resonators." In ASME 2022 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/detc2022-90025.
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Abstract Simultaneous energy harvesting and vibration attenuation has been a topic of great interest in many recent investigations in mechanical metamaterials. These studies have shown the ability to harvest electrical power using weak electromechanical coupling in periodic metamaterials with no effect on the material’s bandgap boundaries. However, the effect of the electromechanical resonator on the topological properties (i.e. the bandgap topology) and localized mode shapes of a quasiperiodic metamaterial has not yet been determined. In this paper, we study a quasiperiodic metamaterial coupled to electromechanical resonators to observe its bandgaps and localized vibration modes. We show here the analytical dispersion surfaces of an infinite quasiperiodic metamaterial with electromechanical local resonators. The natural frequencies of a semi-infinite system are also simulated numerically to validate the analytical results and show the band structure for different quasiperiodic patterns, load resistors, and electromechanical coupling coefficients. Furthermore, the mode shapes are presented here for a semi-infinite structure showing localized vibration within the bandgaps. The results demonstrate that quasiperiodic metamaterials with electromechanical local resonators can be used to harvest energy without changing the topology of the bandgaps for the case of weak electromechanical coupling. The observations given here can be used to guide designers in choosing electromechanical resonator parameters and quasiperiodic pattern parameters for an effective energy harvesting metamaterial.
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Astudillo, Diego, and Rafael O. Ruiz. "Resonator-Based Piezoelectric Metastructures: Efficient Bandgap Estimation and Parametric Analysis." In ASME 2023 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/imece2023-110579.
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Abstract The integration of piezoelectric elements as resonators inside a periodic structure for vibration suppression and energy harvesting (at low frequencies) was experimentally demonstrated recently. In particular, employing a square array of free-standing piezoelectric cantilevers attached to a primary structural frame. The configuration could be understood as a periodic cell that contains a series of cantilevered Piezoelectric Energy Harvesters (PEHs). This work aims to implement a finite element model of a piezoelectric periodic structure capable of presenting vibration suppression and energy harvesting and use it to study the influence of the model parameters on the generated bandgaps. Different frame geometries with cantilever piezoelectric beams are studied. Through these geometrical arrangements, it is found that the domain of the wave vectors that must be evaluated in the Floquet-Bloch periodic condition to identify bandgaps can be restricted to only 5 wave vectors contained in the first Brillouin zone. This issue can be exploited to generate a large decrease in computational resources when optimizing this configuration. The work also presents a parametric analysis to identify the model parameters’ influence on the bandgap’s location and size. The parametric analysis also reveals the need to incorporate uncertainty quantification in the design and optimization process, simultaneously offering comprehensive information about the continuity of the bandgap in relation to the model parameters.
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Song, Yihao, and Yanfeng Shen. "Shape Memory Metamaterials With Adaptive Bandgaps for Ultra-Wide Frequency Spectrum Vibration Control." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-10902.
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Abstract This paper presents a novel shape memory metamaterial, which can achieve adaptively tunable bandgaps for ultra-wide frequency spectrum vibration control. The microstructure is composed of a Shape Memory Alloy (SMA) wire and a metallic spring combined together with bakelite blocks, loaded by a lumped mass made of lead. The adaptive bandgap mechanism is achieved via the large deformation of the metamaterial unit cell structure during the heating and cooling cycle. By applying different heating temperature on the SMA wire, morphing microstructural shapes can be achieved. Parametric design is conducted by adjusting the lead block mass. Finally, an optimized microstructural design rendering a large deformation is chosen. Finite element models (FEMs) are constructed to analyze the dynamic behavior of the metamaterial system. Effective mass density of the unit cell is calculated to investigate and demonstrate the bandgap tuning phenomenon. In the simulation, two extreme shapes are simulated adhering to the experimental observations. The effective negative mass density and the moving trends are obtained, representing the development and shifting of the bandgaps. The width of the bandgap region covers about 50 Hz from the room-temperature state to the heating state. This enables the vibration suppression within this wide frequency region. Subsequently, a metamaterial chain containing ten unit cells is modeled, aligned on an aluminum cantilever beam. An external normal force with a sweeping frequency is applied on the beam near the fixed end. Harmonic analysis is performed to further explore the frequency response of the mechanical system. The modeling results from modal analysis, effective mass density extraction, and harmonic analysis agree well with each other, demonstrating the prowess of the proposed shape memory metamaterial for ultra-wide frequency spectrum control.
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Sugino, Christopher, Stephen Leadenham, Massimo Ruzzene, and Alper Erturk. "Electroelastic Bandgap Formation in Locally Resonant Metamaterial Beams With Piezoelectric Shunts: A Modal Analysis Approach." In ASME 2016 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/smasis2016-9282.
Повний текст джерелаАнотація:
Metamaterials made from flexible structures with piezoelectric laminates connected to resonant shunt circuits can exhibit vibration attenuation properties similar to those of their purely mechanical locally resonant counterparts. Thus, in analogy to purely mechanical metamaterials, electroelastic metamaterials with piezoelectric resonators can exhibit vibration attenuation bandgaps. To enable the effective design of these locally resonant electroelastic metamaterials, the electromechanical behavior of the piezoelectric patches must be reconciled with the modal behavior of the electroelastic structure. To this end, we develop a novel argument for the formation of bandgaps in bimorph piezoelectric beams, relying on modal analysis and the assumption of infinitely many segmented shunted electrodes (unit cells) on continuous piezoelectric laminates bracketing a substrate. As a case study, the frequency limits of the locally resonant bandgap that forms from resonant shunting is derived, and a design guideline is presented to place the bandgap in a desired frequency range. This method can be easily extended to more general circuit impedances, and can be used to design shunt circuits to obtain a desired frequency response in the main structure.
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Sugino, Christopher, Massimo Ruzzene, and Alper Erturk. "Dynamics of Hybrid Mechanical-Electromechanical Locally Resonant Piezoelectric Metastructures." In ASME 2017 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/smasis2017-3948.
Повний текст джерелаАнотація:
Locally resonant metamaterials are characterized by bandgaps at wavelengths much larger than the lattice size, which enables low-frequency vibration attenuation in structures. Next-generation metastructures (i.e. finite metamaterial-based structures) hosting mechanical resonators as well as piezoelectric interfaces connected to resonating circuits enable the formation of two bandgaps, right above and below the design frequency of the mechanical and electrical resonators, respectively. This new class of hybrid metastructures proposed in this work can therefore exhibit a wider bandgap size and enhanced design flexibility as compared to using a purely mechanical, or a purely electromechanical metastructure alone. To this end, we bridge our efforts on modal analysis of mechanical and electromechanical locally resonant metastructures and establish a fully coupled framework for hybrid mechanical-electromechanical metastructures. Combined bandgap size is approximated in closed form for sufficient number of mechanical and electromechanical resonators. Case studies are presented to understand the interaction of these two locally resonating metastructure domains in bandgap formation, and conclusions are drawn for design and optimization of such hybrid metastructures. Numerical results from modal analysis are compared with dispersion analysis using the plane wave expansion method and the proposed analytical framework is validated succesfully.
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CHOI, JEWOO, TONGJUN CHO, SANG GEUN BAE, and HYO SEON PARK. "EXPERIMENTAL INVESTIGATION ON FLEXURAL VIBRATION CONTROL OF LARGE-SCALE REINFORCED CONCRETE METAPLATES." In Structural Health Monitoring 2023. Destech Publications, Inc., 2023. http://dx.doi.org/10.12783/shm2023/36999.
Повний текст джерелаАнотація:
In this study, the vibration control performance of a large-scale reinforced concrete (RC) metaplate is experimentally validated and investigated. The local resonance frequency of plate-type LRM unit is numerically estimated. 4,200 x 3,000 x 210 mm RC metaplate, embedded with 165 LRM units measuring 200 x 200 x 85 mm each, is excited to heavy-weight impact to measure its acceleration responses. The experimental results showed that the generation of a local resonance bandgap in metaplate, leading to vibration control within the bandgap frequency range. The acceleration response of the metaplate is attenuated by up to 85.39 % at the local resonance frequency (42.51 Hz) compared to an RC plate without LRMs. The amplitude of modal peak within the bandgap frequency range is attenuated by up to 71.22 %. Based on the two indicators used to analyzed vibration control performance, The influence of both the local resonance and modal characteristics of the metaplate on its bandgap behavior is analyzed.