• Title/Summary/Keyword: FFR (Free Flooded Ring)

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Analysis and verification of the characteristic of a compact free-flooded ring transducer made of single crystals (압전단결정을 이용한 소형 free-flooded ring 트랜스듀서의 성능 특성 예측 및 검증)

  • Im, Jongbeom;Yoon, Hongwoo;Kwon, Byungjin;Kim, Kyungseop;Lee, Jeongmin
    • The Journal of the Acoustical Society of Korea
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    • v.41 no.3
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    • pp.278-286
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    • 2022
  • In this study, a 33-mode Free-Flooded Ring (FFR) transducer was designed to apply piezoelectric single crystal PIN-PMN-PT, which has high piezoelectric constants and electromechanical coupling coefficient. To ensure low-frequency high transmitting sensitivity characteristics with a small size of FFR transducer, the commercial FFR transducer based on piezoelectric ceramics was compared. To develop the FFR transducer with broadband characteristics, a piezoelectric segmented ring structure inserted with inactive elements was applied. The oil-filled structure was applied to minimize the change of acoustic characteristics of the ring transducer. It was verified that the transmitting voltage response, underwater impedance, and beam pattern matched the finite element numerical simulation results well through an acoustic test. The difference in the transmitting voltage response between the measured and the simulated results is about 1.3 dB in cavity mode and about 0.3 dB in radial mode. The fabricated FFR transducer had a higher transmitting voltage response compared to the commercial transducer, but the diameter was reduced by about 17 %. From this study, it was confirmed that the feasibility of a single crystal-applied FFR transducer with compact size and high-power characteristics. The effectiveness of the performance prediction by simulation was also confirmed.

Equivalent Circuit Modelling of FFR Transducer Array for Sonar System Design (소나 시스템 설계를 위한 FFR 트랜스듀서 어레이의 등가회로 모델링)

  • Kim, In-Dong;Choi, Seung-Soo;Lee, Haksue;Lee, Seung Woo;Moon, Wonkyu
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.66 no.4
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    • pp.629-635
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    • 2017
  • Free-Flooded Ring (FFR) transducer array for use in Sonar system can be driven with large amplitude in a wide frequency band due to its structural characteristics, in which two resonances of a ring mode (1st radial mode) and an inner cavity vibration mode occur in a low frequency band. Since its sound wave generation characteristics are not influenced by the water pressure, the FFR transducer array is widely used in the deep sea. So FFR has been recognized as a low-frequency active sound source and has received much attention ever since. In order to utilize the FFR transducer array for SONAR systems in military and industrial applications, its equivalent electric circuit model is necessary especially to design the matching circuit between the driving power amplifier and the FFR transducer array. Thus this paper proposes the equivalent electric circuit model of FFR transducer array by using measured values of parameter, and suggest the improved method of parameter identification. Finally it verifies the effectiveness of the proposed circuit model of FFR transducer array by experimental measurements.

Design of a FFR-typed High Power Deep-water Sonar Transducer using a Coupled FE-BEM (결합형 유한요소-경계요소 기법에 의한 FFR 형태의 고출력 심해저용 쏘나 변환기 설계)

  • Jarng Soon Suck;Lee Je Hyeong;Ahn Heung Gu;Choi Heun Ho
    • Proceedings of the Acoustical Society of Korea Conference
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    • spring
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    • pp.224-227
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    • 1999
  • A high power deep-water sonar transducer of FFR (Free Flooded Ring) type has been designed using a coupled FE-BEM. The present sonar transducer is composed of rectangular piezoelectric ceramics and pie-shaped steels (or the advantage of simple fabrication. The dynamics of the sonar transducer is modelled in three dimensions and is analyzed with external electrical excitation conditions. Different results are available such as steady-state frequency response for TX and RX displacement modes, directivity patterns, back-scattering patterns, bandwidths, transmitting voltage responses and receiving sensitivity responses. The TV response shows a very high acoustic pressure of 150 dB/lV (ref $1{\mu}Pa$ at 1m) at 1900 Hz. This ultra high power response of the sonar transducer indicates a new possibility of the sonar transducer development.

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Effective material properties of radially poled piezoelectric ring transducer for analysis of tangentially poled piezoelectric ring (원주 분극 압전 링 트랜스듀서 해석을 위한 방사 분극 링 유효 물성 도출)

  • Lee, Haksue;Cho, Cheeyoung;Park, Seongcheol;Cho, Yo-Han;Lee, Jeong-min
    • The Journal of the Acoustical Society of Korea
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    • v.38 no.2
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    • pp.184-192
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    • 2019
  • Compared to 31-mode rings, 33-mode rings are highly utilized as wide bandwidth underwater acoustic transducers because the electro-mechanical coupling and piezoelectric constant d are high. On the other hand, the 31-mode ring is an axial symmetry structure, so it is possible to model it as a simple two-dimensional asymmetrical model for numerical analysis, but the 33-mode ring requires a three-dimensional numerical analysis. That is, a lot of computing resources and computation time are required. In this study, the effective material properties of an equivalent 31-mode ring were derived to simulate the electro-mechano-acoustical responses of the 33-mode ring transducer. Using the effective material properties derived from this study, a numerical analysis of rings in vacuum, air backed rings in water, and FFR (Free Flooded Ring) transducers were performed to compare the responses of 33-mode rings.

Optimal Design of Deep-water 30kHz Omnidirectional Sonar Transducer Using a Coupled FE-BEM

  • Jarng, Soon-Suck
    • The Journal of the Acoustical Society of Korea
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    • v.18 no.4E
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    • pp.3-9
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    • 1999
  • Deep-water sonar transducers of FFR (Free Flooded Ring) type have been designed using a coupled FE-BEM. The proposed sonar transducers are composed of piezoelectric ceramic tubes and structural steel materials for simple fabrication. In order to have an omnidirectional beam pattern around 30kHz, a conic steel is placed below a piezoelectric tube or a steel disc is placed between two piezoelectric tubes. The dynamics of the sonar transducer is modelled in three dimensions and is analyzed with external electrical excitation conditions. Various results are available such as directivity patterns and transmitting voltage responses. The most optimal structure and dimensions of the steel material were calculated, so that the beam patterns of the sonar transducers had +/- 3dB omnidirectivity at 30kHz.

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Optimal Design of Deep-water 30 kHz Omnidirectional Sonar Transducer using a Coupled FE-BEM (결함형 유한요소-경계요소 기법에 의한 심해저용 30 kHz 전방향성 소나 변환기 최적 설계)

  • Jarng Soon Suck;Choi Heun Ho;Lee Je Hyeong;Ahn Heung Gu
    • Proceedings of the Acoustical Society of Korea Conference
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    • autumn
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    • pp.275-280
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    • 1999
  • Deep-water sonar transducers of FFR (Free Flooded Ring) type have been designed using a coupled FE-BEM. The proposed sonar transducers are composed of piezoelectric ceramic tubes and structural steel materials for simple fabrication. In order to have an omnidirectional beam pattern around 30 kHz, a conic steel is placed below a piezoelectric tube or a steel disc is placed between two piezoelectric tubes. The dynamics of the sonar transducer is modelled in three dimensions and is analyzed with external electrical excitation conditions. Various results are available such as directivity patterns and transmitting voltage responses. The most optimal structure and dimensions of the steel material were calculated, so that the beam patterns of the sonar transducers had +/- 3 dB omnidirectivity at 30 kHz.

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