Bibliografias temáticas / Electromechanical admittance

Literatura científica selecionada sobre o tema "Electromechanical admittance"

Autor: Grafiati

Publicado: 25 de maio de 2024

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Artigos de revistas sobre o assunto "Electromechanical admittance"

Ai, Demi, Chengxing Lin, Hui Luo e Hongping Zhu. "Temperature effect on electromechanical admittance–based concrete structural health monitoring". Structural Health Monitoring 19, n.º 3 (9 de julho de 2019): 661–92. http://dx.doi.org/10.1177/1475921719860397.

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Concrete structures in service are often subjected to environmental/operational temperature effects, which change their inherent properties and also inflict a challenge to their extrinsic monitoring systems. Recently, piezoelectric lead zirconate titanate (PZT)-based electromechanical admittance technique has been increasingly growing into an effective tool for concrete structural health monitoring; however, uncertainty in the changes of monitoring signals induced by temperature impact on concrete/PZT sensor would inevitably cause interference to structural damage detection, which adversely hinder its application from laboratory to engineering practice. This article, aiming at exploring the temperature effect on the electromechanical admittance–based concrete damage evaluation, primarily covered a series of theoretical/numerical analysis with rigorously experimental verifications. Three aspects of comparative studies were performed in theoretical/numerical analysis: (1) thermal-dependent parameters were inclusively evaluated in contribution to the electromechanical admittance characteristics via PZT-structure interaction models; (2) three-dimensional finite element analysis in multi-physics coupled field was employed to qualitatively assess the singular temperature effect on the electromechanical admittance behaviors of free-vibrated PZT, surface-bonded PZT/inside-embedded PZT coupled healthy concrete cubes; and (3) depending on the modeling of surface-bonded PZT-/inside-embedded PZT-cracked concrete cube, thermal effect on damage evaluation was addressed via quantification on the electromechanical admittance variations. In the experimental study, rigorous validation tests were carried out on a group of lab-scale concrete cubes, where surface-bonded PZT/inside-embedded PZT transducers were simultaneously employed for electromechanical admittance monitoring in view of thermal difference between concrete surface and its inner part. Correlation coefficient deviation value-based effective frequency shifts algorithm was also employed to compensate the temperature effect. Moreover, temperature effect was further testified on the monitoring of a full-scale shield-tunnel segment structure. Experimental results indicated that temperature triggered different behaviors of electromechanical admittance signatures for surface-bonded PZT/inside-embedded PZT transducers and contaminated the electromechanical admittance responses for damage detection. Structural damage severity level can be disadvantageously amplified by temperature increment even if under the same damage scenarios.

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APARNA, M., M. RAGHAVENDER, G. PRASAD e G. S. KUMAR. "ELECTROMECHANICAL CHARACTERIZATION OF LANTHANUM-DOPED SODIUM BISMUTH TITANATE CERAMICS". Modern Physics Letters B 20, n.º 09 (10 de abril de 2006): 475–80. http://dx.doi.org/10.1142/s0217984906010664.

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The effect of lanthanum doping on the electromechanical properties of lanthanum-doped sodium bismuth titanate was studied. The ferroelectric system under investigation was Na 1/2( La x Bi 1-x)1/2 TiO 3 ceramics, with x=0, 0.1, 0.15 and 0.2. Admittance measurements were carried out in the frequency range of 100 Hz to 13 MHz and in the temperature range from room temperature to 550°C. Combined impedance and admittance spectroscopy was used to analyze admittance data. The electromechanical parameters were calculated from the resonant and anti-resonant frequencies obtained from vector admittance plots. The electromechanical coefficients for pure sodium bismuth titanate ceramic samples were found to be much larger than the reported values. Also, it was observed that lanthanum-doping decreased the values of electromechanical coupling coefficients.

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Xu, Guidong, Baiqiang Xu, Chenguang Xu e Ying Luo. "Temperature effects in the analysis of electromechanical impedance by using spectral element method". Multidiscipline Modeling in Materials and Structures 12, n.º 1 (13 de junho de 2016): 119–32. http://dx.doi.org/10.1108/mmms-03-2015-0015.

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Purpose – The purpose of this paper is to develop a spectral element modeling to predict electromechanical admittance in the surface-bonded piezoelectric wafer and beam structure considering temperature effects. Design/methodology/approach – For modeling the beam, the axial and transverse vibrations of the beam have been considered, and temperature-dependent mechanical and electromechanical properties of piezoelectric wafer active sensor and aluminum have been analyzed. The influences of temperature effects on electromechanical admittance are investigated. Findings – The results show that a frequency left shift and a decrease in amplitude of admittance in any natural frequencies with increasing temperature have been observed. The mechanism of these changes is discussed. Originality/value – The numerical results may be considered helpful for structural health monitoring using electromechanical impedance technique.

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Zuo, Chunyuan, Xin Feng e Jing Zhou. "A Three-Dimensional Model of the Effective Electromechanical Impedance for an Embedded PZT Transducer". Mathematical Problems in Engineering 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/218026.

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A three-dimensional model of the effective electromechanical impedance for an embedded PZT transducer is proposed by considering the interaction between a PZT patch and a host structure. By introducing an effective mechanical impedance, the coupled electromechanical admittance formulations are derived using the piezoelectric constitutive equations. Then, a modified methodology for monitoring structure changes using an electromechanical impedance (EMI) technique is proposed. In the proposed method, the changes in the host structure are monitored by using the “active” part associated with the structural mechanical impedance, which is extracted from the measured raw admittance signatures. The strength gain of a concrete beam with embedded PZT transducers during the curing age was monitored with the proposed methodology. The experimental results demonstrate that the use of the “active” part is more sensitive as opposed to the raw admittance signatures for structural health monitoring (SHM).

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Providakis, Costas P. "Repair of Cracked Structures under Dynamic Load Using Electromechanical Admittance Approach". Key Engineering Materials 348-349 (setembro de 2007): 49–52. http://dx.doi.org/10.4028/www.scientific.net/kem.348-349.49.

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In the present paper, the repair of a cracked structure under dynamic load using the electromechanical admittance (EMA) approach is investigated. Conceptually, appropriate electrical field are applied on the outer surfaces of piezoelectric (PZT) patches to effect closure of the crack. This has the effect of altering the electromechnaical (E/M) admittance signature, extracted at the electrical terminals of a specific PZT patch, considered as an admittance calculating sensor (ACS) patch, towards that of the healthy structure, which is the criterion concept used for the repair in this paper. To demonstrate the present repair methodology, a cantilever 3D beam numerical example is considered in combination with a FEM-based minimization of the difference between the healthy and cracked structure’s (E/M) admittance signature, for specific frequency ranges.

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VIJAYA BHASKAR RAO, P., e T. BHIMA SANKARAM. "ELECTRO MECHANICAL AND IMPEDANCE STUDIES OF (Na1-xKx)1/2Bi1/2TiO3". International Journal of Modern Physics B 23, n.º 14 (10 de junho de 2009): 3131–45. http://dx.doi.org/10.1142/s0217979209052443.

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Ceramic samples of [( Na 1-x K x)1/2 Bi 1/2 TiO 3] (NKBT) (x = 0.1, 0.15, 0.2, 0.3, 0.45) were prepared by double sintering method. The admittance measurements were carried out in the frequency range of 1 KHz to 10 MHz in the temperature range of 30°C–600°C. The dielectric nature as deduced from admittance data shows a strong temperature and frequency dependence, apart from the relaxor behavior. The admittance data was analyzed by complex plane diagrams i.e., Y′ versus Y′′ at different temperature. The frequency explicit plots of imaginary component of electric modulus (M′′) at various temperatures show peaks shifting to higher frequencies with temperature (> 400° C ). The relaxation peaks were effected by the doping. The activation energies are obtained from the data. The electromechanical coefficients KP, K31 were calculated from the resonant and anti-resonant frequencies obtained from vector admittance plots. The temperature dependence of electromechanical coefficients is studied. The solid solution samples show higher KP, K31 values as compared to pure sodium bismuth titanate.

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Karlash, V. "Modeling of the energy-loss piezoceramic resonators by electric equivalent networks with passive elements". Mathematical Modeling and Computing 1, n.º 2 (2014): 163–77. http://dx.doi.org/10.23939/mmc2014.02.163.

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This paper is devoted to analysis of the modern achievements in energy loss problem for piezoceramic resonators. New experimental technique together with computing permits us to plot many resonators' parameters: admittance, impedance, phase angles, and power components etc. The author's opinion why mechanical quality under resonance is different from that under anti-resonance is given. The reason lies in clamped capacity and electromechanical coupling factor's value. The better electromechanical coupling, the stronger capacity clamping, and the higher its influence on anti-resonant frequency and quality. It is also established that considerable nonlinearity of admittance in constant voltage regime is caused by instantaneous power level.

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Sofuoğlu, Mehmet A., Gökhan Haydarlar, Melih C. Kuşhan, Sezan Orak e Mesut Tekkalmaz. "Investigation of electromechanical impedance and residual stress relation for samples machined by hot ultrasonic-assisted turning". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 236, n.º 8 (30 de outubro de 2021): 4180–93. http://dx.doi.org/10.1177/09544062211050473.

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Electromechanical impedance (EMI) method has been widely used in recent years to evaluate the condition of structures. In this method, piezoelectric sensors are added to the structure to examine material properties. The impedance/admittance signals are recorded with the aid of the impedance analyzer without any conversion. When there is any change in structures, differences occur in these signals. Thus, changes in structures can be easily determined. It is known that residual stress plays a vital role in materials in terms of crack initiation, breakage, fatigue life, etc. In contrast, the detection of residual stress is time-consuming and it requires experience. This study reveals the effect of cutting parameters on residual stress and electromechanical impedance/admittance values. Firstly, hot ultrasonic-assisted turning was performed for Ti6Al4V material. A parametric study was carried out with different cutting depth, feed rate, and cutting speed. In the second stage, residual stress values measured by X-Ray diffraction (XRD) method and impedance/admittance values measured by an impedance analyzer were compared. In this context, empirical equations with their values between stress/impedance–admittance values have been derived. In general, it has been observed that stress values are significantly associated with impedance/admittance values and the highest correlation was obtained with the reactance values.

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Choi, S.-B., H. S. Kim e J.-S. Park. "New design methodology for piezoelectric shunt structures using admittance analysis". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, n.º 2 (1 de fevereiro de 2008): 131–45. http://dx.doi.org/10.1243/09544062jmes591.

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In this paper, a new design method for a piezoelectric shunt circuit to reduce unwanted vibration of flexible structures is proposed. Admittance is introduced to represent electromechanical characteristics of piezoelectric structures and to predict the performance of piezoelectric shunt system. It is shown that admittance of the piezoelectric structure is proportional to the dissipated energy in the shunt circuit. Admittance is used as a design index to construct the piezoelectric shunt system and obtained by finite-element method. The location, area, shape, and material property of piezoelectric patches are determined by admittance analysis. Vibration reduction of the piezoelectric structure with shunt circuit is realized by experiments. It is proved from damped system response of the piezoelectric structure in frequency and time domains that the admittance is proportional to the performance of the piezoelectric shunt system. A flow chart for design procedures using admittance analysis is presented to save design cost of the piezoelectric shunt system.

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Zhang, Chenxu. "Pavement damage monitoring using electromechanical impedance of embedded piezoelectric plate". Applied and Computational Engineering 25, n.º 5 (30 de novembro de 2023): 30–42. http://dx.doi.org/10.54254/2755-2721/25/ojs/20230729.

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Piezoelectric transducers have seen widespread usage in the monitoring of structural health. It has tremendous potential for monitoring the health of infrastructure, especially pavement monitoring. In the present study, the impedance characteristics of a piezoelectric plate embedded in the pavement is utilized to monitor the health status of the pavement. Based on the piezoelectricity principle, a model of an electromechanical piezoelectric plate embedded in pavement is established. The damage of the pavement is considered as the thickness decreasing of the pavement layer. The present proposed model is verified by comparing its degeneration with the exact solution of a single layer model. Numerical results demonstrated that with the deceasing of the thickness of the pavement, which is considered as the deterioration of the pavement, the achievable maximum electromechanical impedance characterization including impedance, admittance and conductance decreased. This demonstrated that the achievable maximum impedance, admittance and conductance of an embedded piezoelectric plate could be used as the indicator of pavement health monitoring. This study primarily presents theoretical underpinnings for pavement monitoring using electromechanical impedance of piezoelectric plates.

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Mais fontes

Teses / dissertações sobre o assunto "Electromechanical admittance"

Ding, Wenxiang. "Structural health monitoring of piezoelectric ultrasonic transducers". Electronic Thesis or Diss., Bourges, INSA Centre Val de Loire, 2021. http://www.theses.fr/2021ISAB0008.

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Les transducteurs à ultrasons ont été largement utilisés dans le diagnostic médical, la thérapie, l'évaluation non destructive, le nettoyage, le sonar et d'autres applications. Le bon fonctionnement du transducteur lui-même est un facteur clé de la fiabilité globale du système. Cependant, en raison d'une mauvaise utilisation par l’opérateur ou d'une dégradation des matériaux, des défauts peuvent survenir tels que des ruptures dans le câblage, des fissures dans les matériaux passifs, l’endommagement des matériaux actifs, une délamination entre les couches constitutives du dispositif ... Ce travail de thèse porte sur une analyse détaillée de l'influence de délaminations sur les performances du transducteur, visant à déterminer des procédures pour faciliter le suivi du comportement du transducteur pendant sa durée de vie et la détection des dégradations avant qu'elles n'affectent significativement les performances du système dans son ensemble.Dans le cadre de ce travail, un modèle analytique bidimensionnel original pour l’étude des vibrations couplées dans les résonateurs piézoélectriques est proposé. Des solutions générales pour toutes les grandeurs physiques dans les systèmes de coordonnées cartésiennes et cylindriques sont déduites des équations tensorielles de la piézoélectricité. Elles sont exprimées sous forme de séries de fonctions trigonométriques ou de Bessel. L'impédance électrique, la forme du mode et le spectre de fréquences des céramiques piézoélectriques sont calculés par la méthode analytique proposée ainsi que par la méthode des éléments finis. La comparaison des résultats de ces deux méthodes montre un excellent accord.Une étude systématique de l'influence de différents types de délaminations sur les performances des transducteurs ultrasonores monoéléments et multi-éléments est présentée. Des modèles par éléments finis sont développés pour montrer l'impact des différents types de délaminations ainsi que d'autres facteurs sur l'admittance électromécanique (EMA) de transducteurs composés soit d'un disque soit de parallélépipèdes de céramiques piézoélectriques, d'un milieu arrière et d'une lame adaptatrice. Des études expérimentales sont mises en place pour valider les modèles et des indicateurs quantitatifs sont proposés. Des éléments sont réalisés en impression 3D (milieu arrière, lame adaptatrice) et montés sur des échantillons de céramiques piézoélectriques pour obtenir un transducteur modèle intact et des transducteurs modèles avec délaminations. La comparaison entre les résultats numériques et expérimentaux montre un bon accord et permet d’affirmer que des modifications de l'EMA peuvent révéler l'apparition et l'étendue d'une délamination entre les éléments constitutifs d’une sonde échographique
Ultrasonic transducers have been widely used in medical diagnostic, therapy, non-destructive evaluation, cleaning, underwater sonar, and other applications. The proper functioning of the transducer itself is a key factor in the reliability of the entire system. However, due to the misuse of operators or material degradation, defects may occur, such as breakages in cables, cracks, damaged or weakened crystals, and delamination between layers. This contribution focuses on a detail analysis of the influence of bonding delamination on the performance of the transducer, aiming to determine procedures to facilitate the monitoring of the behavior of the transducer during its lifetime and the detection of degradations before they significantly affect the performance of the system.In the frame of this work, an original two-dimensional analytical model for coupled vibrations of finite piezoelectric resonators is proposed. General solutions for all the physical quantities in Cartesian and cylindrical coordinate systems are deduced from the governing equations. They are expressed as a series of trigonometric or Bessel functions. Electrical impedance, mode shape, and frequency spectrum of piezoceramics are calculated by the proposed analytical method as well as by the finite element method. Comparison of the results of these two methods shows an excellent agreement.A systematic investigation of the influence of different kinds of bonding delamination on the performance of single-element and linear array ultrasonic transducers is presented. Finite element models are developed to show the impact of bonding delamination as well as other factors on the electromechanical admittance (EMA) of ultrasonic transducers, which are composed of a piezoceramic disk or parallelepiped, a backing, and a matching layer. Experimental studies are set up to validate the models and quantitative indicators are proposed. 3D printed backings and matching layers are mounted on piezoceramic elements to obtain an intact model transducer and delaminated ones. Comparison between numerical and experimental results show a good agreement, which allows to affirm that changes in EMA can reveal the occurrence and extent of a delamination in an ultrasound probe

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Capítulos de livros sobre o assunto "Electromechanical admittance"

Providakis, C. P. "Repair of Cracked Structures under Dynamic Load Using Electromechanical Admittance Approach". In Advances in Fracture and Damage Mechanics VI, 49–52. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-448-0.49.

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Trabalhos de conferências sobre o assunto "Electromechanical admittance"

Otitoju, Shola, Hanz Richter e Antonie J. van den Bogert. "Admittance control for an electromechanical rowing machine". In 2016 IEEE International Conference on Advanced Intelligent Mechatronics (AIM). IEEE, 2016. http://dx.doi.org/10.1109/aim.2016.7576757.

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Zhang, Yang, Kai Zhou e Jiong Tang. "Memetic Optimizer for Structural Damage Identification Using Electromechanical Admittance". 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/detc2022-91039.

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Abstract Electromechanical impedance-based (EMI) techniques using piezoelectric transducers are promising for structural damage identification. They can be implemented in high frequency range with small characteristic wavelengths, leading to high detection sensitivity. The impedance measured is the outcome of harmonic and stationary excitation, which makes it easier to conduct inverse analysis for damage localization and quantification. Nevertheless, the EMI data measurement points are usually limited, thus oftentimes resulting in an under-determined problem. To address this issue, damage identification process can be converted into a multi-objective optimization formulation which naturally yields multiple solutions. While this setup fits the nature of damage identification that a number of possibilities may exist under given observations/measurements, existing algorithms may suffer from premature convergence and entrapment in local extremes. Consequently, the solutions found may not cover the true damage scenario. To tackle these challenges, in this research, a series of local search strategies are tailored to enhance the global searching ability and incorporated into particle swarm-based optimization. The Q-table is utilized to help the algorithm select proper local search strategy based on the maximum Q-table values. Case studies are carried out for verification, and the results show that the proposed memetic algorithm achieves good performance in damage identification.

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Chen, Yuntong, e Siyi Lu. "Study of six-degree-of-freedom wave characteristics simulator based on admittance control". In Fourth International Conference on Artificial Intelligence and Electromechanical Automation (AIEA 2023), editado por Fushuan Wen, chuanjun Zhao e Yanjiao Chen. SPIE, 2023. http://dx.doi.org/10.1117/12.2684879.

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Zhao, Liuxian, Lingyu Yu, Mattieu Gresil, Michael Sutton e Siming Guo. "Electromechanical Impedance Modeling for Structural Health Monitoring". In ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/smasis2012-8094.

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Electromechanical impedance (EMI) method is an effective and powerful technique in structural health monitoring (SHM) which couples the mechanical impedance of host structure with the electrical impedance measured at the piezoelectric wafer active sensor (PWAS) transducer terminals. Due to the electromechanical coupling in piezoelectric materials, changes in structural mechanical impedance are reflected in the electrical impedance measured at the PWAS. Therefore, the structural mechanical resonances are reflected in a virtually identical spectrum of peaks and valleys in the real part of the measured EMI. Multi-physics based finite element method (MP-FEM) has been widely used for the analysis of piezoelectric materials and structures. It uses finite elements taking both electrical and mechanical DOF’s into consideration, which allows good differentiation of complicated structural geometries and damaged areas. In this paper, MP-FEM was then used to simulate PWAS EMI for the goal of SHM. EMI of free PWAS was first simulated and compared with experimental result. Then the constrained PWAS was studied. EMI of both metallic and glass fiber composite materials were simulated. The first case is the constrained PWAS on aluminum beam with various dimensions. The second case studies the sensitivity range of the EMI approach for damage detection on aluminum beam using a set of specimens with cracks at different locations. In the third case, structural damping effects were also studied in this paper.. Our results have also shown that the imaginary part of the impedance and admittance can be used for sensor self-diagnosis.

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Coorpender, Steven J., Daniel Finkel, Jennifer Kyzar, Robert Sims, Alexandra B. Smirnova, Mohamed Tawhid, Chad E. Bouton e Ralph C. Smith. "Modeling and Optimization Issues Concerning a Circular Piezoelectric Actuator Design". In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0544.

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Abstract An electromechanical model for a circular piezoelectric actuator is developed. A critical challenge in certain applications employing piezoceramic actuators is to maximize the displacement provided by the actuator while minimizing it power consumption. This problem is addressed here by developing an electromechanical model which can be used to optimize the volume displacement to admittance ratio for various circular actuator designs. The model includes multiple layers with independent radii which can be varied to optimize performance. The piezoceramic, bonding, plating, and mounting materials can be varied to accommodate various design criteria. An advantage of the model lies in the property that for a variety of material configurations, analytic solutions can be obtained. Numerical examples demonstrating the properties of the model are presented.

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Zhang, Boying, Hamad Hameed, Yuxin Xu, Chonglin Zhang e Yong Bai. "Electromechanical Impedance Method for Damage Detection of Typical Joint on Jacket Platform". In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77385.

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Health monitoring of welded structural joints is a very important factor of the engineering community. Electro-mechanical impedance (EMI) technique allows the direct evaluation of structural dynamics by evaluating its E/M impedance or admittance signatures. This paper first gives a brief introduction of the theoretical background on the described method. Then, the described EMI technique is applied to recognize the presence of damage by executing experimental works where the damage in the form of crack is simulated with an impedance analyzer at various distances. Four typical welded metallic joints on a jacket platform successfully produced submillimeter cracks under cyclic loading and root mean square deviation (RMSD) is used to evaluate the degree of crack damage. Finally, an outcome of laboratory measurements performed with developed structural health monitoring system based on the electromechanical impedance phenomenon is presented.

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Dai, Zishu, Yongchang Cai, Yiying Han e Jiao Tian. "Influence of Parameter Variation on Electromechanical Admittance Spectrum of a Multiple Degree of Freedom System". In 2015 International Conference on Mechatronics, Electronic, Industrial and Control Engineering. Paris, France: Atlantis Press, 2015. http://dx.doi.org/10.2991/meic-15.2015.354.

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Maheshwari, Muneesh, Venu Gopal Madhav Annamdas, John H. L. Pang, Swee Chuan Tjin e Anand Asundi. "Fibre optic sensors for load-displacement measurements and comparisons to piezo sensor based electromechanical admittance signatures". In SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, editado por Peter J. Shull. SPIE, 2015. http://dx.doi.org/10.1117/12.2084039.

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Shahab, Shima, e Alper Erturk. "Underwater Dynamic Actuation of Macro-Fiber Composite Flaps With Different Aspect Ratios: Electrohydroelastic Modeling, Testing, and Characterization". In ASME 2014 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/smasis2014-7538.

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Macro-fiber composite (MFC) actuators offer simple and scalable design, robustness, noiseless performance, strong electromechanical coupling, and particularly a balance between the actuation force and deformation capabilities, which is essential to effective and agile biomimetic locomotion. Recent efforts in our lab have shown that MFC bimorphs with polyester electrode sheets can successfully be employed for fish-like aquatic locomotion in both tethered and untethered operation. MFC swimmers can outperform other smart material-based counterparts, such as the compliant ionic polymer-metal composite based swimmers, in terms of swimming speed per body length. Cantilevered flaps made of MFC bimorphs with different aspect ratios can be employed for underwater actuation, sensing, and power generation, among other aquatic applications of direct and converse piezoelectric effects. In an effort to develop linearized electrohydroelastic models for such cantilevers, the present work investigates MFC bimorphs with three different aspect ratios. The MFCs used in this study use the 33-mode of piezoelectricity with interdigitated electrodes. Underwater dynamic actuation frequency response functions (FRFs) of the MFCs are defined as the tip velocity per actuation voltage (tip velocity FRF) and current consumption per actuation voltage (admittance FRF). The tip velocity and admittance FRFs are modeled analytically for in-air actuation and validated experimentally for all aspect ratios. Underwater tip velocity and admittance FRFs are then derived by combining their in-air counterparts with corrected hydrodynamic functions. The corrected hydrodynamic functions are also identified from aluminum cantilevers of similar aspect ratios. Both tip vibration and current consumption per voltage input are explored. The failure of Sader’s hydrodynamic function for low length-to-width aspect ratios is shown. Very good correlation is observed between model simulations and experimental measurements using aspect ratio-dependent, corrected hydrodynamic function.

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Giurgiutiu, Victor, e Craig A. Rogers. "Modeling of the Electro-Mechanical (E/M) Impedance Response of a Damaged Composite Beam". In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0525.

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Abstract The electro-mechanical (E/M) impedance method has gained acceptance as an effective technique for structural health monitoring, damage detection, and failure prevention. In spite of extensive experimental validation of this novel method, very little work has been dedicated to its modeling. This paper develops a model of the E/M impedance response of a damaged composite beam interrogated by a PZT wafer active sensor. The electromechanical model for the interaction between the beam and the active sensor is developed from first principles. The effective axial force and bending moments induced by the PZT wafer into the beam are considered. Equations of motion for the flexural vibrations of a composite beam under moment excitation are developed. Solution in terms of normal modes with internal damping is obtained. The resulting response and the applied force are utilized to deduce general expressions for pointwise dynamic stiffness and pointwise dynamic compliance. Effective stiffness of the PZT wafer is also calculated, and the complex stiffness ratio for the PZT-structure interaction is determined. Hence, the complex electro-mechanical impedance and admittance are deduced. A numerical example is given to illustrate the method and test its effectiveness. It is found that the real part of the effective pointwise dynamic stiffness interacts at par with the PZT stiffness at structural resonance frequencies. The imaginary part of the complex stiffness ratio directly reflects the pointwise structural resonances. Consequently, the real part of the electro-mechanical impedance directly reflects the pointwise structural resonances too. The same behavior is also found in the electro-mechanical admittance. Thus, the real part of the E/M impedance and the real part of the E/M admittance are found to be direct measures of the structural response, reflective of damage presence.

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