• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.26 no.6
• /
• pp.434-440
• /
• 2013

With polymer properties and ceramic volume fraction as design variables, the optimal structure of 1-3 piezocomposites has been determined to maximize the thickness mode electromechanical coupling factor. When the piezocomposite vibrates in a thickness mode, inter-pillar resonant modes are likely to occur between lattice-structured piezoceramic pillars and polymer matrix, which significantly deteriorates the performance of the piezocomposite. In this work, a new method to design the structure of the 1-3 type piezocomposite is proposed to maximize the thickness mode electromechanical coupling factor while preventing the occurrence of the inter-pillar modes. Genetic algorithm was used for the optimal design, and the finite element analysis method was used for the analysis of the inter-pillar mode.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.26 no.11
• /
• pp.790-800
• /
• 2013

The optimal structure of 1-3 piezocomposites has been determined by controlling polymer properties, ceramic volume fraction, thickness of composite and aspect ratio of the composite to maximize the TVR (transmitting voltage response), RVS (receiving voltage sensitivity) and FBW (fractional bandwidth) of underwater acoustic transducers. Influence of the design variables on the transducer performance was analyzed with equivalent circuits and the finite element method. When the piezocomposite is vibrating in a pure thickness mode, inter-pillar resonant modes are likely to occur between lattice-structured piezoceramic pillars and polymer matrix, which significantly deteriorate the performance of the piezocomposite. In this work, a new method to design the structure of the 1~3 type piezocomposite was proposed to maximize the TVR, RVS and FBW while preventing the occurrence of the inter-pillar modes. Genetic algorithm was used in the optimal design.

• 전자공학회논문지 IE
• /
• v.48 no.2
• /
• pp.40-46
• /
• 2011

In this study, PZT-5A green sheet were prepared by using tape casting technique, and the piezoelectric properties of PZT-5A by variation of sintering temperature was investigated. After, design and piezoelectric properties of 2-2 piezocomposite ultrasonic transducers by menas of the FEA. The acoustic impedance and piezoelectric charge constant of the 2-2 type piezocomposite transducer decreased proportionally due to the density decrease caused by the PZT volume fraction decrease. The piezocomposite acoustic impedance were 7~3 MRayl between 0.6 and 0.2 allowing it to be used for a ultrasonic transducer. The resonance characteristics and the electro-mechanical coupling factor were the best when the volume fraction PZT was 0.6. The PZT volume fraction shows the fixed value, 0.6~0.65, approximately within the range between 0.2 and 0.6 while it is increased to decreased over the range. The result of the experiment above confirmed that the 2-2 piezoelectric composites could be used as the ultrasonic transducers.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2004.10a
• /
• pp.282-285
• /
• 2004

The main purpose of this study is the vibration suppression of rotating composite blade containing distributed piezoelectric sensors and actuators. The blade is modeled by thin-walled, single cell composite beam including the warping function, centrifugal force, Coriolis acceleration and piezoelectric effect. Further, the numerical study is performed m ing finite element method. The vibration of composite rotor is suppressed by piezocomposite actuators and PVDF sensors that are embedded between composite layers. A velocity feedback control algorithm coupling the direct and converse piezoelectric effect is used to actively control the' dynamic response of an integrated structure through a closed control loop. Responses of the rotating blade are investigated. Newmark time integration method is used to calculate the time response of the model. In the numerical simulation, the effect of parameters such as rotating speed, fiber orientation of the blade and size of actuators are studied in detail.

• The Journal of the Acoustical Society of Korea
• /
• v.30 no.8
• /
• pp.436-445
• /
• 2011

In this paper, equivalent properties of 2-2 mode piezocomposites were studied. Variation of the properties of 2-2 mode piezocomposites was analyzed by the finite element method, and the result was compared with experimental measurement data to confirm the validity of the analysis. The equivalent properties of a single phase material to represent the piezocomposite composed of PZT-5H and polymer were derived by the asymptotic averaging method. Accuracy of the derived equivalent properties was enhanced by minimizing the discrepancy between the impedance spectra of full 2-2 piezocomposite and equivalent single phase material resonators of various vibration modes by the least square method. The equivalent properties of 2-2 piezocomposites derived in this study can be utilized to the design of diverse acoustic sensors.

• Journal of Sensor Science and Technology
• /
• v.27 no.6
• /
• pp.374-379
• /
• 2018

The piezocomposite transducer is widely used because it is highly efficient in transforming electric energy into mechanical energy, and its frequency range is broader than that of other types of ultrasound transducers. A general piezocomposite transducer is composed of an acoustic lens, impedance matching layers, piezoelectric materials, and backing layers. When an input voltage is applied to a piezoelectric material as an active material, it generates sound waves while vibrating. At that time, an impedance matching layer helps the sound waves to propagate forward while reducing the impedance mismatch that may occur at the interface between the active material and its front material. The impedance mismatch has a negative effect on the signal of an ultrasound transducer; thus, it is important to design a matching layer to overcome the issue. In this study, an optimized feature of a matching layer with gradient properties is studied. An objective function is defined to minimize both the average and the deviation of the reflection coefficients that are functions of the frequencies. As a result, an improvement in the signal characteristics with respect to the sensitivity and bandwidth is reported.

• The Journal of the Acoustical Society of Korea
• /
• v.42 no.5
• /
• pp.377-387
• /
• 2023

This paper presents accuracy of a method that directly estimates equivalent properties of a 1-3 piezocomposite for modeling it into the single phase homogeneous piezomaterial. This direct estimation method finds individual components of a material property matrix based on the piezoelectric constitutive equations, which represent mechanical and electrical behaviors and their couplings. Equivalent properties on a single 1-3 piezocomposite hydrophone are derived, and their accuracy depending on pairing of the constitutive equations is investigated by comparing them with finite element analysis for the whole domain. The accuracy is related to elastic characteristics of a matrix polymer, and the error is analyzed so that some guidelines for correct estimation are suggested. Fidelity of estimated properties and equivalent modeling is shown in a stave scale including hydrophones and surrounding acoustic structures as well, and reduced computational cost is verified.

• The Journal of the Acoustical Society of Korea
• /
• v.23 no.4
• /
• pp.274-281
• /
• 2004

In this study. a 1-3 piezo-composite single element ultrasonic transducer was designed with a commercial finite element analysis (FEA) code. PZf1ex and developed based on this design. Design with FEA could be performed overcoming many constraints of the typical theoretical method, and also was very practical. Validity of the design with the FEA was illustrated through experimental characterization of fabricated 1-3 piezo-composites and ultrasonic transducers, Through comparison with the result of the theoretical method. we confirmed the superiority of the design method using FEA.

• Smart Structures and Systems
• /
• v.13 no.4
• /
• pp.547-565
• /
• 2014

This paper investigates the design of a perfect point load actuator based on flat triangular piezoelectric patches. Applying a difference of electric potential between the electrodes of a triangular patch leads to point loads at the tips and distributed moments along the edges of the electrodes. The previously derived analytical expressions of these forces show that they depend on two factors: the width over height (b/l) ratio of the triangle, and the ratio of the in-plane piezoelectric properties ($e_{31}/e_{32}$) of the active layer of the piezoelectric patch. In this paper, it is shown that by a proper choice of b/l and of the piezoelectric properties, the moments can be cancelled, so that if one side of the triangle is clamped, a perfect point load actuation can be achieved. This requires $e_{31}/e_{32}$ to be negative, which imposes the use of interdigitated electrodes instead of continuous ones. The design of two transducers with interdigitated electrodes for perfect point load actuation on a clamped plate is verified with finite element calculations. The first design is based on a full piezoelectric ceramic patch and shows superior actuation performance than the second design based on a piezocomposite patch with a volume fraction of fibres of 86%. The results show that both designs lead to perfect point load actuation while the use of an isotropic PZT patch with continuous electrodes gives significantly different results.

• The Journal of the Acoustical Society of Korea
• /
• v.28 no.8
• /
• pp.806-814
• /
• 2009

This paper reviews a study about sound reflection control using an active sound absorber. An active sound absorber includes sound transmitting and receiving piezocomposite sensor layers molded by water tight epoxy, and connected with a feedback controller. The multi-layer sensors and the controller consists a closed feedback loop, whose intrinsic characteristics shows excellent impedance matching performance within specified frequency band, and consequently, minimizes reflection waves. Multilayer sound transmission model is derived based on one dimensional model, and its performance is verified with experiment using a pulse tube setup.