• 대한기계학회논문집A
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• 제20권10호
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• pp.3173-3185
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• 1996

Multi-model vibration control of laminated composites plates for various fiver orientations has been carried out by making use of piezolectric materials(PZT) as sensors and actuators. Cantilever plate is used as a specimen to test multi-modal vibration supression under random exitation. Impulse technique is applied to determine the natural frequency, the damping ratio(.zeta.) and the modal damping(2.zeta..omega.) of the first bending and the trosion modes. Two independent controllers are implemented to control the two modes simultaneously and established digitally on the basis of the direct negative velocity feedback control with collocated sensor/actuator. Experimental results for various fiber orientations and feedback gains are compared with finite element analysis considering stiffnesses and dampings of piezoeletiric sensors, actuators and bonding layer.

• 소음진동
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• 제10권6호
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• pp.1048-1058
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• 2000

본 논문에서는 압전 세라믹 재료를 작동기 및 감지기로 이용한 사각 경계면이 고정된 얇은 사각평판의 능동 진동제어 방법을 제시한다. 실험 데이터에 기초한 다중 입출력계의 주파수영역 모델링방법을 이용하여 분포된 센서 및 구동기 특성이 포함된 구조물의 동적 특성이 규명된다. 제어기 구조로는 혼합형을 채택하고 되먹임 제어기는 LQG 제어기법에 의해 설계된다. 앞먹임 제어기는 다중 filtered-$x$ 최소자승오차법에 의해 적응되도록 한다. 진동제어에 대한 시뮬레이션 및 실험결과는 제안된 제어기법이 지속적 외란 및 과도적 외란에 효율적으로 적용될 수 있음을 보인다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.508-514
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• 2005

This paper is concerned with the active vibration control of a grid structure equipped with piezoceramic sensors and actuators. The grid structure is a replica of the solar panel commonly mounted on satellites, which contains complex natural mode shapes. The multi input and multi output positive position feedback controller is considered as an active vibration controller for the grid structure. A new concept, the block-inverse technique, is proposed to cope with more modes than the number of actuators and sensors. This study also deals with the stability and the spillover effect associated with the application of the multi-input multi-output positive position feedback controller based on the block inverse technique. It was found that the theories developed in this study are capable of predicting the control system characteristics and its performance. The new multi-input multi-output positive position feedback controller was applied to the test structure using a digital signal processor and its efficacy was verified by experiments..

• 한국소음진동공학회논문집
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• 제15권9호
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• pp.1037-1044
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• 2005

This paper is concerned with the active vibration control of a grid structure equipped with piezoceramic sensors and actuators. The grid structure is a replica of the solar panel commonly mounted on satellites, which contains complex natural mode shapes. The multi-input and multi-output positive position feedback controller is considered as an active vibration controller for the grid structure. A new concept, the block-inverse technique, is proposed to cope with more modes than the number of actuators and sensors. This study also deals with the stability and the spillover effect associated with the application of the multi-input multi-output positive position feedback controller based on the block-inverse technique. It was found that the theories developed in this study are capable of predicting the control system characteristics and its performance. The new multi-input multi-output positive position feedback controller was applied to the test structure using a digital signal processor and its efficacy was verified by experiments.

• 한국음향학회지
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• 제32권1호
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• pp.32-42
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• 2013

일반적인 수중 탐지용 압전 구형 센서는 무지향성이어서 스칼라 양인 수신 음압의 크기만 측정할 뿐 전파 방향은 측정 할 수 없는 한계를 가지고 있다. 본 논문에서는 이러한 구형 센서를 이용해 음파의 크기와 방향을 동시에 찾을 수 있는 방법을 제안한다. 제안한 방법은 구형 센서의 압전 세라믹을 8등분하여 배열한 다음, 각 압전 세라믹 출력전압을 특정한 방법으로 조합하여 음압의 크기와 방향을 파악할 수 있도록 하였다. 또한 압전세라믹 구의 반경과 두께와 같은 구조 변수들의 변화에 따른 감도 변화를 분석하여, 벡터 센서의 감도를 향상 시킬 수 있는 방안을 제시하였다.

• Smart Structures and Systems
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• 제17권2호
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• pp.167-194
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• 2016

This paper investigates the Synergetics based Damage Detection Method (SDDM) for frame structures by using surface-bonded PZT (Lead Zirconate Titanate) patches. After analyzing the mechanism of pattern recognition from Synergetics, the operating framework with cooperation-competition-update process of SDDM was proposed. First, the dynamic identification equation of structural conditions was established and the adjoint vector (AV) set of original vector (OV) set was obtained by Generalized Inverse Matrix (GIM).Then, the order parameter equation and its evolution process were deduced through the strict mathematics ratiocination. Moreover, in order to complete online structural condition update feature, the iterative update algorithm was presented. Subsequently, the pathway in which SDDM was realized through the modified Synergetic Neural Network (SNN) was introduced and its assessment indices were confirmed. Finally, the experimental platform with a two-story frame structure was set up. The performances of the proposed methodology were tested for damage identifications by loosening various screw nuts group scenarios. The experiments were conducted in different damage degrees, the disturbance environment and the noisy environment, respectively. The results show the feasibility of SDDM using piezoceramic sensors and actuators, and demonstrate a strong ability of anti-disturbance and anti-noise in frame structure applications. This proposed approach can be extended to the similar structures for damage identification.

• Structural Engineering and Mechanics
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• 제42권2호
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• pp.211-228
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• 2012

Present study deals with the development of finite element based solution methodology to investigate active control of dynamic response of delaminated composite shells with piezoelectric sensors and actuators. The formulation is based on first order shear deformation theory and an eight-noded isoparametric element is used. A coupled piezoelectric-mechanical formulation is used in the development of the constitutive equations. For modeling the delamination, multipoint constraint algorithm is incorporated in the finite element code. A simple negative feedback control algorithm coupling the direct and converse piezoelectric effects is used to actively control the dynamic response of delaminated composite shells in a closed loop employing Newmark's time integration scheme. The validity of the numerical model is demonstrated by comparing the present results with those available in the literature. A number of parametric studies such as the locations of sensor/actuator patches, delamination size and its location, radius of curvature to width ratio, shell types and loading conditions are carried out to understand their effect on the transient response of piezoceramic delaminated composite shells.

• 대한기계학회논문집A
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• 제25권9호
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• pp.1410-1415
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• 2001

Active control of sound radiation from a vibrating rectangular plate by a steady-state harmonic point force disturbance is experimentally studied. Structural excitation is achieved by two piezoceramic actuators mounted on the panel. Two accelerometers are implemented as error sensors. Estimated radiated sound signals using vibro-acoustic path transfer function are used as error signals. The vibro-acoustic path transfer function represents system between accelerometers and microphones. The approach is based on a multi-channel filtered-x LMS algorithm. The results shows that attenuation of sound levels of 11dB, 10dB is achieved.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
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• pp.432-437
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• 1998

This paper presents modal characteristics of bowl parts feeder featuring piezoelectric actuators. As wellknown, the piezoelectric materials develop an electric charge proportional to a mechanical stress and vice versa. This generic phenomenon allows us to use the piezoelectric materials as sensors and actuators. Using the actuating property, we can device effective bowl parts feeder. The parts feeder activated by the piezoceramic actuators provides a large degree of freedom of controlling excitation magnitude and frequency, and thus accurate and fast feeding of various parts. As a first phase to demonstrate these advantages, a finite clement model of the bowl parts feeder is constructed and analyzed using commercial software packages. In addition, the simulated modal characteristics are compared with the measured ones to validate the proposed model.

• Smart Structures and Systems
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• 제6권2호
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• pp.147-165
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• 2010

Impact damage detection in composite structures has gained a considerable interest in many engineering areas. The capability to detect damage at the early stages reduces any risk of catastrophic failure. This paper compares two advanced signal processing methods for impact location in composite aircraft structures. The first method is based on a modified triangulation procedure and Genetic Algorithms whereas the second technique applies Artificial Neural Networks. A series of impacts is performed experimentally on a composite aircraft wing-box structure instrumented with low-profile, bonded piezoceramic sensors. The strain data are used for learning in the Neural Network approach. The triangulation procedure utilises the same data to establish impact velocities for various angles of strain wave propagation. The study demonstrates that both approaches are capable of good impact location estimates in this complex structure.