• Title/Summary/Keyword: Macro Fiber Composite (MFC)

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A study on the underwater energy harvesting characteristics of a funnel type macro fiber composite energy harvester (수중에서 퍼넬형 macro fiber composite 에너지 하베스터의 에너지 수확 특성)

  • Jongkil Lee;Jinhyo An
    • The Journal of the Acoustical Society of Korea
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    • v.42 no.1
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    • pp.57-66
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    • 2023
  • In this paper, it was investigated how the amount of energy harvesting will be varied from the FTEH which has inlet area is wider than outer area and attaching cantilever type MFC (Macro Fiber Composite) using by theoretical and experimental approaches. When MFC length increased 50 % vibration displacement also increased 3.5 times. When thickness decreased vibration displacement increased 30.9 times. In underwater tank experiments FTEH with spiral screw, flexible support, vertical direction fabrication cases showed maximum energy harvesting more 5 times than the case of MFC installed horizontally without spiral screws and on rigid supports. When the flow speed of 0.24 m/s FTEH's optimal resistance applied 4,10 kΩ, energy storage in the capacitor was measured 4 ㎼·s during 350 seconds. It was confirmed that the charging energy can be increased by lengthening the capacitor charging time of the large-area MFC installed vertically on the flexible support at high flow speed.

Modeling techniques for active shape and vibration control of macro-fiber composite laminated structures

  • Zhang, Shun-Qi;Chen, Min;Zhao, Guo-Zhong;Wang, Zhan-Xi;Schmidt, Rudiger;Qin, Xian-Sheng
    • Smart Structures and Systems
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    • v.19 no.6
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    • pp.633-641
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    • 2017
  • The complexity of macro-fiber composite (MFC) materials increasing the difficulty in simulation and analysis of MFC integrated structures. To give an accurate prediction of MFC bonded smart structures for the simulation of shape and vibration control, the paper develops a linear electro-mechanically coupled static and dynamic finite element (FE) models based on the first-order shear deformation (FOSD) hypothesis. Two different types of MFCs are modeled and analyzed, namely MFC-d31 and MFC-d33, in which the former one is dominated by the $d_{31}$ effect, while the latter one by the $d_{33}$ effect. The present model is first applied to an MFC-d33 bonded composite plate, and then is used to analyze both active shape and vibration control for MFC-d31/-d33 bonded plate with various piezoelectric fiber orientations.

Feasibility of MFC (Macro-Fiber Composite) Transducers for Guided Wave Technique

  • Ren, Gang;Yun, Dongseok;Seo, Hogeon;Song, Minkyoo;Jhang, Kyung-Young
    • Journal of the Korean Society for Nondestructive Testing
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    • v.33 no.3
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    • pp.264-269
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    • 2013
  • Since MFC(macro-fiber composite) transducer has been developed, many researchers have tried to apply this transducer on SHM(structural health monitoring), because it is so flexible and durable that it can be easily embedded to various kinds of structures. The objective of this paper is to figure out the benefits and feasibility of applying MFC transducers to guided wave technique. For this, we have experimentally tested the performance of MFC patches as transmitter and sensors for excitation and reception of guided waves on the thin aluminum alloy plate. In order to enhance the signal accuracy, we applied the FIR filter for noise reduction as well as used STFT(short-time Fourier transform) algorithm to image the guided wave characteristics clearly. From the results, the guided wave generated based on MFC showed good agreement with its theoretical dispersion curves. Moreover, the ultrasonic Lamb wave techniques based on MFC patches in pitch-catch manner was tested for detection of surface notch defects of which depths are 10%, 20%, 30% and 40% of the aluminum plate thickness. Results showed that the notch was detectable well when the notch depth was 10% of the thickness or greater.

Morphing wing using Macro Fiber Composite actuator (압전섬유작동기를 이용한 형상적응날개)

  • Na, Young-Ho;Kim, Ji-Hwan
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2005.04a
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    • pp.9-12
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    • 2005
  • Recently, research on the morphing wing is an interesting issue to develop the capability of the wing such as improving the lift and reduction of drag during the operation of an aircraft by changing the wing shape from one configuration to another. A more efficient weight reduction of the wing using smart or morphing wing concept can be achieved in comparison with the conventional flaps. In this study, it is investigated the behaviors of the morphing wing using Macro Fiber Composite (MFC) actuators. Generally, MFC is the piezocomposite actuator with the rectangular PZT fiber and epoxy matrix, and uses the interdigitated electrode to produce more powerful actuation in the in-plane direction. Furthermore, it can produce the twisting actuation as compared with the traditional PZT actuators. In the formulation, the first-order shear deformation plate theory is used, and finite element method is adopted in the numerical analysis of the model. Results show the characteristics of the static behavior of the morphing wing according to the change of the actuation voltage.

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The actuation equation of macro-fiber composite coupled plate and its active control over the vibration of plate and shell

  • Tu, Jianwei;Zhang, Jiarui;Zhu, Qianying;Liu, Fan;Luo, Wei
    • Structural Monitoring and Maintenance
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    • v.5 no.2
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    • pp.297-311
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    • 2018
  • Plate and shell structure is widely applied in engineering, i.e. building roofs, aircraft wings, ship platforms, and satellite solar arrays. Its vibration problem has become increasingly prominent due to the tendency of lightening, upsizing and flexibility. As a new smart material with great actuating force and toughness, macro-fiber composite (MFC) is composed of piezoelectric fiber and epoxy resin basal body, which can be directly pasted onto the surface of plate and shell and is suitable for vibration control. This paper deduces the actuation equation of MFC coupled plate in different boundary conditions, an equivalent finite element modeling method is proposed which uses MFC actuating force as the applied excitation, and on this basis the active control simulation and experiment of MFC over plate and shell structure vibration are accomplished. The results indicate that MFC is able to implement effective control over plate and shell structure vibration in multi-band range. The comparison between experiment and simulation proves that the actuation equation deduced herein, effective and practicable, can be applied into the simulation calculation of MFC vibration control over plate and shell structure.

Acoustic Emission (AE) Technology-based Leak Detection System Using Macro-fiber Composite (MFC) Sensor (Macro fiber composite (MFC) 센서를 이용한 음향방출 기술 기반 배관 누수 감지 시스템)

  • Jaehyun Park;Si-Maek Lee;Beom-Joo Lee;Seon Ju Kim;Hyeong-Min Yoo
    • Composites Research
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    • v.36 no.6
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    • pp.429-434
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    • 2023
  • In this study, aimed at improving the existing acoustic emission sensor for real time monitoring, a macro-fiber composite (MFC) transducer was employed as the acoustic emission sensor in the gas leak detection system. Prior to implementation, structural analysis was conducted to optimize the MFC's design. Consequently, the flexibility of the MFC facilitated excellent adherence to curved pipes, enabling the reception of acoustic emission (AE) signals without complications. Analysis of AE signals revealed substantial variations in parameter values for both high-pressure and low-pressure leaks. Notably, in the parameters of the Fast Fourier Transform (FFT) graph, the change amounted to 120% to 626% for high-pressure leaks compared to the case without leaks, and approximately 9% to 22% for low-pressure leaks. Furthermore, depending on the distance from the leak site, the magnitude of change in parameters tended to decrease as the distance increased. As the results, in the future, not only will it be possible to detect a leak by detecting the amount of parameter change in the future, but it will also be possible to identify the location of the leak from the amount of change.

Structural and Aerodynamic Characteristics of A Flapping Wing with Changeable Camber Using A Smart Material (스마트 재료를 이용한 캠버 변화가 가능한 플래핑 날개 구조 및 공력 특성)

  • Kim, Dae-Kwan;Kim, Hong-Il;Kwon, Ki-Jung;Han, Jae-Hung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.5
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    • pp.390-396
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    • 2007
  • In the present study, we have developed a flapping wing using a smart material to mimic the nature's flyers, birds. The wing consists of composite frames, a flexible PVC film and a surface actuator, and the main wing motions are flapping, twisting and camber motions. To change the camber, a Macro-Fiber Composite(MFC) is used as the surface actuator, and it's structural response is analyzed by the use of piezoelectric-thermal analogy. To measure the lift and thrust simultaneously, a test stand consisting of two load cells is manufactured. Some aerodynamic tests are performed for the wing in a subsonic wind tunnel to evaluate the dynamic characteristics. Experimental results show that the main lift is mostly affected by the forward velocity and the pitch angle, but the thrust is mostly affected by the flapping frequency. The effect of the camber generated by the MFC actuator can produce the sufficient lift increment of up to 24.4% in static condition and 20.8% in dynamic condition.

Active Vibration Control of Underwater Hull Structure Using Macro-Fiber Composite Actuators (MFC 작동기를 이용한 수중 Hull 구조물의 능동 진동 제어)

  • Kwon, Oh-Cheol;Sohn, Jung-Woo;Choi, Seung-Bok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.2
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    • pp.138-145
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    • 2009
  • Structural vibration and noise are hot issues in underwater vehicles such as submarines for their survivability. Therefore, active vibration and noise control of submarine, which can be modeled as hull structure, have been conducted by the use of piezoelectric materials. Traditional piezoelectric materials are too brittle and not suitable to curved geometry such as hull structures. Therefore, advanced anisotropic piezocomposite actuator named as Macro-Fiber Composite(MFC), which can provide great flexibility, large induced strain and directional actuating force is adopted for this research. In this study, dynamic model of the smart hull structure is established and active vibration control performance of the smart hull structure is evaluated using optimally placed MFC. Actuating performance of MFC is evaluated by finite element analysis and dynamic modeling of the smart hull structure is derived by finite element method considering underwater condition. In order to suppress the vibration of hull structure, Linear Quadratic Gaussian(LQG) algorithm is adopted. After then active vibration control performance of the proposed smart hull structure is evaluated with computer simulation and experimental investigation in underwater. Structural vibration of the hull structure is decreased effectively by applying proper control voltages to the MFC actuators.

Damage detection for pipeline structures using optic-based active sensing

  • Lee, Hyeonseok;Sohn, Hoon
    • Smart Structures and Systems
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    • v.9 no.5
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    • pp.461-472
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    • 2012
  • This study proposes an optics-based active sensing system for continuous monitoring of underground pipelines in nuclear power plants (NPPs). The proposed system generates and measures guided waves using a single laser source and optical cables. First, a tunable laser is used as a common power source for guided wave generation and sensing. This source laser beam is transmitted through an optical fiber, and the fiber is split into two. One of them is used to actuate macro fiber composite (MFC) transducers for guided wave generation, and the other optical fiber is used with fiber Bragg grating (FBG) sensors to measure guided wave responses. The MFC transducers placed along a circumferential direction of a pipe at one end generate longitudinal and flexural modes, and the corresponding responses are measured using FBG sensors instrumented in the same configuration at the other end. The generated guided waves interact with a defect, and this interaction causes changes in response signals. Then, a damage-sensitive feature is extracted from the response signals using the axi-symmetry nature of the measured pitch-catch signals. The feasibility of the proposed system has been examined through a laboratory experiment.

Dynamic Characteristics Modification of Damaged Composite Structure Using MFC and Active Control Algorithm (MFC와 능동 제어를 이용한 손상된 복합재의 동적 특성 복원)

  • Sohn, Jung Woo;Kim, Heung Soo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.12
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    • pp.1066-1072
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    • 2013
  • In this work, active control algorithm is adopted to reduce delamination effects of the damaged composite structure and control performance with MFC actuator is numerically evaluated. Finite element model for the damaged composite structure with piezoelectric actuator is established based on improved layerwise theory. In order to achieve high control performance, MFC actuator, which has increased actuating force, is considered as a piezoelectric actuator. Mode shapes and corresponding natural frequencies for the damaged smart composite structure are studied. After design and implementation of active controller, dynamic characteristics of the damaged smart composite structure are investigated.