• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.126-129
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• 2001

LIPCA (LIghtweight Piezo-composite Curved Actuator) is an actuator device which is lighter than other conventional piezoelectric ceramic type actuator. LIPCA is composed of a piezoelectric ceramic layer and fiber reinforced light composite layers, typically a PZT ceramic layer is sandwiched by a top fiber layer with low CTE (coefficient of thermal expansion) and base layers with high CTE. LIPCA has curved shape like a typical THUNDER (thin-layer composite unimorph feroelectric driver and sensor), but it is lighter an than THUNDER. Since the curved shape of LIPCA is from the thermal deformation during the manufacturing process of unsymmetrically laminated lay-up structure, an analysis for the thermal deformation and residual stresses induced during the manufacturing process is very important for an optimal design to increase the performance of LIPCA. To investigate the thermal deformation behavior and the induced residual stresses of LIPCA at room temperature, the curvatures of LIPCA were measured and compared with those predicted from the analysis using the classical lamination theory. A methodology is being studied to find an optimal stacking sequence and geometry of LIPCA to have larger specific actuating displacement and higher force. The residual stresses induced during the cooling process of the piezo-composite actuators have been calculated. A lay-up geometry for the PZT ceramic layer to have compression stress in the geometrical principal direction has been designed.

• International Journal of Aeronautical and Space Sciences
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• 제12권1호
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• pp.69-77
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• 2011

A peristaltic micropump with lightweight piezo-composite actuator (LIPCA) membrane valves is presented. The micropump contained three cylinder chambers that were connected by microchannels and two active membrane valves. A circular miniature LIPCA was developed and manufactured to be used as actuating diaphragms. The LIPCA diaphragm acted as an active membrane valve that alternate between open and closed positions at the inlet and outlet in order to produce high pumping pressure. In this LIPCA, a lead zirconium titanate ceramic with a thickness of 0.1 mm was used as an active layer. The results confirmed that the actuator produced a large out-of-plane deflection. During the design process, a coupled field analysis was conducted in order to predict the actuating behavior of the LIPCA diaphragm; the behavior of the actuator was investigated from both a theoretical and experimental perspective. The active membrane valve concept was introduced as a means for increasing pumping pressure, and microelectromechanical system techniques were used to fabricate the peristaltic micropump. The pumping performance was analyzed experimentally in terms of the flow rate, pumping pressure and power consumption.

• 한국항공우주학회지
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• 제30권5호
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• pp.94-100
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• 2002

본 논문은 곡면형 압전 복합재료 작동기 LIPCA의 개발 및 성능 실험에 관한 것이다. LIPCA는 압전 세라믹을 중심으로 상층부는 탄성계수가 크면서 열팽창계수가 낮은 섬유강화 복합재료층이 위치하며, 하층부는 탄성계수가 작으면서 열팽창계수가 큰 섬유강화 복합재료층이 위치한다. 작동기의 성능 검증을 위해 작동지그 및 전압 공급 장치 그리고 비접촉 레이저 센서로 이루어진 실험 시스템을 구성하였다. 성능 실험은 양단 단순지지상태에서 압전 재료의 전극에 $100\sim400V_{pp}$의 교류 전압을 1Hz로 가하였을 경우 작동기 중앙부에서 발생하는 수직방향의 변위를 측정하는 것으로 수행하였다. LIPCA와 THUNDER의 성능 검증 결과 LIPCA-C2는 THUNDER에 비해 34% 경량화 되었으며, 작동변위는 13% 향상되었다.

• Composites Research
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• 제27권2호
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• pp.47-51
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• 2014

본 논문은 기존의 유/공압 및 전기식 모터를 대체할 수 있는 경량, 고성능 지능소자 구동기를 설계/제작하고 이를 소형 무인비행체의 조종익 시스템에 적용 가능성을 연구한 것이다. 또한 압전 복합재료 작동기에 대한 성능평가를 수행하였으며, 유니모프 및 바이모프 형태의 작동기를 제작하여 각각의 작동 특성을 확인하였다. 이와 같은 성능시험 평과 결과를 통해 바이모프 형태의 작동기가 하중 유무와 무관하게 선형적인 받음각 변화를 가짐을 알 수 있었다. 이러한 지능소자 구동 시스템은 소형 로봇, 유도무기 및 MAV, UAV의 조종익 제어 시스템으로 사용될 수 있는 가능성을 확인하였다.

• 대한기계학회논문집A
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• 제25권10호
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• pp.1514-1519
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• 2001

This paper is concerned with design, manufacturing and performance test of LIPCA ( Lightweight Piezo- composite Curved Actuator) using a top carbon fiber composite layer with near -zero CTE(coefficient of thermal expansion), a middle PZT ceramic wafer and a bottom glass/epoxy layer with high CTE. The main point of this design is to replace the heavy metal layers of THUNDER by thigh tweight fiber reinforced plastic layers without losing capabilities to generate high force and large displacement. It is possible to save weight up to about 30% if we replace the metallic backing material by the light fiber composite layer. We can also have design flexibility by selecting the fiber direction and the size of prepreg layers. In addition to the lightweight advantage and design flexibility, the proposed device can be manufactured without adhesive layers when we use epoxy resin prepreg system. Glass/epoxy prepregs, a ceramic wafer with electrode surfaces, and a graphite/epoxy prepreg were simply stacked and cured at an elevated temperature (177 $^{circ}C$ after following an autoclave bagging process. It was found that the manufactured composite laminate device had a sufficient curvature after detached from a flat mold. The analysis method of the cure curvature of LIPCA using the classical lamination theory is presented. The predicted curvatures are fairly in agreement with the experimental ones. In order to investigate the merits of LIPCA, a performance test of both LIPCA and THUNDE$^{TM}$ were conducted under the same boundary conditions. From the experimental actuation tests, it was observed that the developed actuator could generate larger actuation displacement than THUNDERT$^{TM}$.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.286-289
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• 2004

This paper presents the fatigue characteristics of LIPCA (LIghtweight Piezo-Composite Actuator) device system. The LIPCA device system is composed of a piezoelectric ceramic layer and fiber reinforced lightweight composite layers. Typically a PZT ceramic layer is sandwiched by a top fiber layer with low CTE (coefficient of thermal expansion) and base layers with high CTE. The advantages of the LIPCA design are weight reduction by using the lightweight fiber reinforced plastic layers without compromising the generation of high force and large displacement and design flexibility by selecting the fiber direction and the size of prepreg layers. To predict the degradation of actuation performance of LIPCA due to fatigue, the cyclic electric loading tests using PZT specimens were performed and the strain for a given excitation voltage was measured during the test. The results from the PZT fatigue test were implemented into CLPT (Classical Laminated Plate Theory) model to predict the degradation of LIPCA's actuation displacement. The fatigue characteristic of PZT was measured using a test system composed of a supporting jig, a high voltage power supplier, data acquisition board, PC, and evaluated.

• Composites Research
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• 제16권2호
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• pp.41-47
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• 2003

본 논문은 몇 가지 종류의 압전 복합재료 작동기 LIPCA의 성능 시험 및 비교에 관한 것이다. LIPCA는 압전 세라믹을 중심으로 상층부는 탄성계수가 크면서 열팽창계수가 낮은 섬유강화 복합재료 층이, 하층부는 탄성계수가 작으면서 열팽창계수가 큰 섬유강화 복합재료 층으로 구성되어 있다. 작동기의 성능 검증을 위해 작동 지그 및 전압 공급 장치 그치고 비접촉 레이저 센서로 이루어진 실험 시스템을 구성하였다 성능 비교시험 결과 검증실험으로부터 압전 작동기의 작동성능은 전기 작동 재료층이 중립면으로부터 멀리 벗어나게 위치하면서, 동시에 적층판의 전체 굽힘 강성을 작게 하면 극대화할 수 있다는 사실을 입증하였다.

• 대한기계학회논문집A
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• 제25권11호
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• pp.1881-1886
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• 2001

A numerical method for actuating performance evaluation of LIPCA proposed using a finite element method. Fully coupled formulations for piezo-electric materials were introduced and 3-dimensional eight-node incompatible element was used. After verifying the developed code with typical examples, the center deflections of LIPCA were calculated and compared with the experimental result, which were in fairly agreement.

• 한국항공우주학회지
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• 제35권3호
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• pp.218-224
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• 2007

PZT와 같은 압전 재료는 능동 진동 억제 분야에서 널리 사용되고 있지만 단일 PZT의 경우 장착 과정에서의 손상, 전기 누전, 낮은 피로 성능과 같은 문제가 지적되고 있다. 이러한 문제를 해결하기 위하여 개발된 LIPCA 작동기는 여러 층의 복합재료와 PZT 층으로 구성되어 있다. 본 연구에서는 LIPCA 작동기를 끝단 질량이 부착된 알루미늄 외팔보의 진동을 억제하는데 적용하였다. 양변위 되먹임 제어 알고리듬을 사용하였으며, 필터 주파수를 대상 모드의 첫 번째 고유진동수에 맞추었다. 실험적으로 구한 알루미늄 보의 고유 진동수는 유한요소 해석의 결과와 잘 일치하였다. LIPCA 작동기를 능동 진동제어에 적용할 때 효율성을 시간과 주파수 영역에서 확인하고자 하였는데, 실험 결과 PPF제어를 사용한 LIPCA 작동기가 자유 진동의 안정화 시간과 강제 진동의 진폭을 효과적으로 제어할 수 있었다. 사례 연구로 다른 두께를 가지는 보의 강제 진동 제어를 수행하였다.

• Advanced Composite Materials
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• 제18권4호
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• pp.327-338
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• 2009

In this paper, through an evaluation process conducted on several designs of mini-LIPCA (Lightweight Piezo-Composite curved Actuator), an optimal design of a mini-LIPCA has been proposed. Comparing with the LIPCA-C2, the design of the mini-LIPCA comes with reduced overall size and a thinner active layer. Since a variation in the number and lay-up of fiber composite layers may strongly affect the performance of the device, one is able to configure several designs of mini-LIPCA. The evaluation process is then followed in order to determine a configuration which characterizes the possibly optimal performance. That is, a design of a mini-LIPCA is said to be optimal if it is capable of producing a maximum out-of-plane displacement. The size of the LIPCA to be investigated was selected to be $10\;mm\;{\times}\;20\;mm$ in which the thickness of PZT plate is about 0.1 mm. The thickness of glass/epoxy and carbon/epoxy are about 0.09 mm and 0.1 mm, respectively. The evaluation process has been conducted thoroughly, i.e., analytical estimation, numerical approximation and the experimental measurement are all involved. Firstly, the design equation was used to calculate essential parameters of proposed lay-up configurations. Secondly, ANSYS, a commercial FEA package, was utilized to estimate displacement outputs of the actuators upon being excited. Finally, experimental measurements were able to verify the predicted results.