• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.8
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• pp.690-695
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• 2005

We have investigated on the development of 2-2 mode piezocomposites that have better piezoelectric activity and lower acoustic impedance than those of conventional piezoceramics. In this study, we have investigated the electrical properties and acoustic impedance of 2-2 mode piezocomposite which were fabricated using the dice-and-fill technique for the different volume fractions of PZT The volume shrinkage of polymer is an important factor in 2-2 mode piezocomposites fabrication. The thickness mode electromechanical coupling factor($\kappa_t$) of PZT was compared with that of piezocomposites. It was shown that the 2-2 mode piezocomposites were much better than the PZT only. The acoustic impedance of 2-2 mode piezocomposites decreased linearly when PZT volume fraction was decreased.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.215-218
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• 2005

We have investigated on the development of 2-2 piezocomposites that have better piezoelectric activity and lower acoustic impedance than those of conventional piezoceramics. In this study, we have investigated the piezoelectric and acoustic properties of 2-2 piezocomposites sensor which were fabricated using dice-and-fill technique for the different volume fraction of PZT. The resonance characteristics measured by an impedance analyzer were similar to the analysis of finite element method. The resonance characteristics and the electromechanical coupling factor were the best when the volume fraction PZT was 0.6. It also showed the highest result from the standpoint of sensitivity, bandwidth and ring-down property and so on at the same condition. The specific characteristics shows that the 2-2 piezocomposites turned out to be superior to the ultrasonic sensor composed by single phase PZT.

• The Journal of the Acoustical Society of Korea
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• v.26 no.2
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• pp.80-86
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• 2007

We have investigated on the development of 2-2 type piezocomposites that have better piezoelectric activity and lower acoustic impedance than those of conventional piezoceramics. In this study, we have investigated the piezoelectric and acoustic properties of 2-2 type piezocomposites sensor which was fabricated using dice-and-fill technique for the different volume fraction of PZT. The specific acoustic impedance of 2-2 type piezocomposites decreased linearly when PZT volume fraction was decreased. The resonance characteristics measured by an impedance analyzer(HP4194A) were similar to the analysis of finite element method (FEM). The resonance characteristics and the electromechanical coupling factor were the best when the volume fraction PZT was 0.6. It also showed the highest result from the standpoint of sensitivity, bandwidth and ring-down property and so on at the same condition. The specific characteristics show that the 2-2 type piezocomposites turned out to be superior to the ultrasonic sensor composed by single phase PZT.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.146-149
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• 2002

In this study, 2-2 type piezocomposites were made and characteristics as volume fraction of PZT were investigated. The accoustic impedance of 2-2 piezoelectric composites was linearly decreased with decreasing PZT volume fraction. when the volume fraction of PZT was 0.2 the acoustic impedance was 3.2 Mrayl. The electromechanical coupling factor was favourable in comparison with the single phase PZT, and that was about uniformed about 0.68 in the 0.2 to 0.6 of PZT volume fraction.

• The Journal of the Acoustical Society of Korea
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• v.30 no.7
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• pp.368-376
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• 2011

Piezoelectric composites have been widely used in broadband acoustic transducers because of their lower acoustic impedance and higher electro-mechanical coupling factor. However, their complex structure has placed many limitations on the design of various transducers. This paper suggests the methodology to substitute the 1-3 piezocomposites by a single-phased material that has properties equivalent to those of the piezocomposites. The resonant method and finite element analysis (FEA) are used to derive the equivalent properties that can accurately depict resonant properties at various vibration modes of the piezocomposites. Validity of the suggested method is confirmed by comparing frequency characteristics of fabricated 1-3 piezocomposite specimens and FEA models. Further, accuracy of the derived material constants is checked by applying the equivalent properties to FEA models of the single phase material for various resonant modes.

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

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06d
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• pp.1-4
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• 1998

본 논문에서는순수 압전세라믹에 비해 동등이상의 압적특성을 가지면서도 음향임피던스가 월등히 낮은 1-3형 압적복합체를 이용한 탐촉자의 개발에 관해 연구하였다. 압전 복합재료 탐촉자는 그 자체만으로 측정대상체와의 음향임피던스 차를 최소화하여 별도의 정합층을 필요로 하지 않는 특징을 가진다. 이를 위하여 본 연구에서는 복합재료에 사용되는 고분자재료의 물성값 설계와, 압전세라믹과의 적절한 배합구조와 형상의 결정에 주안점을 두었다. 그 결과를 바탕으로 압전 복합체 초음파 트랜스듀서 시작품을 제작하고 그성능을 분석하였으며, 이론적인 시뮬레이션 결과과의 비교를 통해 설계이론의 타당성을 검증하였다.

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

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.35-38
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• 2003

In this paper, we investigated the electric and acoustic properties of piezoelectric composites, which were fabricated using polymer and piezoelectric ceramics, when the volume fraction of PZT varies. Practically, the shrinkage rate of polymer is an important factor in ultrasonic transducer fabrication. When 10 wt% filler A was added into polymer(Epofix), the lowest shrinkage was resulted. The electromechanical coupling factor($k_t$) of the fabricated piezoelectric composites showed its highest when the volume fraction PZT was 0.6. It decreased if the volume fraction was higher than the value. The relative permittivity and acoustic impedance of piezoelectric composites decreased linearly when PZT volume fraction was decreased. The lowest acoustic impedance was 3.2 when the volume fraction of PZT was 0.2.

• The Journal of the Acoustical Society of Korea
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• v.17 no.8
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• pp.48-57
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• 1998

본 논문에서는 순수 압전세라믹에 비해 동등이상의 압전특성을 가지면서도 음향임 피던스가 월등히 낮은 1-3형 압전복합체를 이용한 탐촉자의 개발에 관해 연구하였다. 압전 복합재료 탐촉자는 그 자체만으로 측정대상체와의 음향임피던스 차를 최소화하여 별도의 정 합층을 필요로 하지 않는 특징을 가진다. 이를 위하여 본 연구에서는 복합재료에 사용되는 고분자 재료의 물성값 설계와, 압전세라믹과의 적절한 배합구조와 형상의 결정에 설계의 주 안점을 두었다. 그 결과를 바탕으로 압전복합체 초음파 트랜스듀서 시작품을 제작하고 그 성능을 분석하였으며, 이론적인 시뮬레이션 결과와의 비교를 통해 설계이론의 타당성을 검 증하였다. 본 연구에서는 수립되어진 압전복합체 트랜스듀서의 설계 및 제작기법은 향후, 측 정대상체와의 정합을 위해 정합층에 대해 복잡한 설계 및 제작공정을 거쳐야하는 다양한 탐 촉자 개발에 유용하게 활용될 수 있을 것이다.