Authors: In Pil Kang, Joo Yung Jung, Gyeong Rak Choi, Hyung Ki Park, Jong Won Lee, Kwang Joon Yoon, Yeo Heung Yun, Vesselin N. Shanov, Mark J. Schulz
Abstract: To address the need for new smart materials, this paper explores the use of carbon
nanotubes to develop a nanocomposite smart material having electrochemical impedance properties
for sensing and actuation. Fabrication and characterization of the carbon nanocomposite material
are discussed in the paper. The issues related to hurdles in the practical manufacturing of
commodity level macro size nanocomposite smart materials with prescribed electrical and
electrochemical properties are also discussed.
207
Authors: Sung Hyuk Lee, Seok Heo, Cheol Woong Kim, Kwang Joon Yoon
Abstract: The behavior of a circular piezoelectric actuator for volumetric micropump has been
investigated by using theoretical and finite element analyses. A modified theoretical model was
developed to predict the behavior of a piezoelectric actuator induced by the applied voltage. The
theoretical results for the diaphragm deflection were in good agreement with the results from
numerical simulation. Based on the theoretical analysis, the effects of several important parameters
on actuation performance have been investigated. These parameters include the dimensions and
mechanical properties of the piezoelectric disk, bonding layer and elastic diaphragm materials.
Consequently, it is thought that above theoretical model might be employed as a tool for design and
optimization of the piezoelectric actuator for micropump application.
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Authors: Ngoc Trung Nguyen, Kwang Joon Yoon
Abstract: Research on piezoelectric unimorph actuators has been intensively increased during the
past decade due to the wide applications of this actuator type in aerospace, vibration control,
biomimetic robots, artificial muscles… Most analyses focused on the design performance with
load-free actuating condition. Loading performance has not been considered adequately yet though
in real application the actuators always work under certain carrying load. This paper introduces the
measuring system, the experimental setup and presents the observed loading performance of the
actuators with center load. Two typical kinds of piezoelectric unimorph actuator, LIPCA-C3 and
THUNDER, are investigated. The numerical analyses are also conducted to illustrate the loading
behavior of these devices. Some remarks and suggestions for future research activities are drawn.
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Authors: In Pil Kang, Hyo Byung Chae, Ki Hoon Park, Kwang Joon Yoon, Li Li Xin, Tae Sam Kang
Abstract: A smart material actuator is required for a smart structure having multifunctional performance.
Among the smart material actuators, piezoelectric actuator is known for its excellent large force generation
in broad bandwidth in a compact size. However it needs relatively large actuation voltage requiring a bulky
hardware system. This study is mainly concerned to develop a self-powered miniaturized piezoelectric
actuator driver (MIPAD) controlled by a radio controller for small sized piezoelectric smart structures. It can
receive command from other microprocessors or a remote radio controller. We designed a real hardware and
it demonstrated good performances even though the driving system was very small. The MIPAD is expected
to minimize the weight and size of the piezoelectric actuator system and it can be easily embedded into
mobile smart structures.
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Authors: June Sung Joe, Hoon Cheol Park, Kwang Joon Yoon, Nam Seo Goo
Abstract: In this paper, a smart skin, i.e. a conformal load-bearing antenna structure, which is a
multi-layer sandwich structure composed of carbon/epoxy, glass/epoxy and dielectric material,
designs, analyses, fabrications and tests are conducted. Mechanical properties of each structural layer
of the designed smart skin are obtained from experimental tests. Tests and analyses are conducted to
study the deformation behavior of the smart skin under compressive loads. The measured data are
compared with the numerical results from geometrically linear/nonlinear finite element analyses.
Numerical prediction for the buckling load of the smart skin agreed well with the experimental data.
963
Authors: In Pil Kang, Jong Won Lee, Gyeong Rak Choi, Joo Yung Jung, Sung Ho Hwang, Yeon Sun Choi, Kwang Joon Yoon, Mark J. Schulz
Abstract: This paper introduces a new sensor design based on a carbon nanotube structural neuron
for structural health monitoring applications. The carbon nanotube neuron is a thin and narrow
polymer film sensor that is bonded or deposited onto a structure. The electrochemical impedance
(resistance and capacitance) of the neuron changes due to deterioration of the structure where the
neuron is located. A network of the long carbon nanotube neurons can form a structural neural
system to provide large area coverage and an assurance of the operational health of a structure
without the need for actuators and complex wave propagation analyses that are used with other
SHM methods. The neural system can also reduce the cost of health monitoring by using
biomimetic signal processing to minimize the number of channels of data acquisition needed to
detect damage. The carbon nanotube neuron is lightweight and easily applied to the structural
surface, and there is no stress concentration, no piezoelectrics, no amplifier, and no storage of high
frequency waveforms. The carbon nanotube neuron is expected to find applications in detecting
damage and corrosion in large complex structures including composite and metallic aircraft and
rotorcraft, bridges, and almost any type of structure with almost no penalty to the structure.
140
Authors: Hery Setiawan, Kwang Joon Yoon, Hoon Cheol Park, Nam Seo Goo
Abstract: This paper addresses the power consumption of the LIPCA (LIghtweight Piezo-Composite Actuator) device system when electric input was applied at its resonance frequency. 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. An experimental set-up was specially designed to measure the power consumption of the LIPCA. By measuring the capacitance of the PZT ceramic wafer during the test, the electric power that consumed can be determined. Experimental results revealed a significant increase in capacitance of the PZT ceramic wafer with an increase in the frequency of applied voltage around the natural frequency of the actuator.
1181
Authors: Kwang Joon Yoon, J.D. Lee, K.B. Kim, Hoon Cheol Park, Nam Seo Goo
Abstract: This paper is concerned with the development of stacked ceramic thin actuation layer IDEAL (Inter-Digitated Electrode Actuation Layer) using d33 actuation mechanism of piezoelectric ceramic. Most of the thin piezoelectric actuators are operated with d31 actuation mechanism. Many kinds of piezoelectric ceramic actuators are strived now to improve the actuation performance. One of efforts to improve performance of piezoceramic actuators is the research trying to develop an actuator using the piezoelectric coefficient d33. The piezoelectric coefficient d33 is almost twice larger than piezoelectric coefficient d31. Therefore, the induced strain of PZT thin layer with d33 actuation mechanism is bigger than that with d31 actuation mechanism. The AFC and LaRC-MFC used d33 actuation mechanism with surface interdigitated electrode to enhance its actuation performance. But their actuation mechanism is not perfect d33 actuation mechanism since the interdigitated electrodes are placed at the surface of the actuation layer. In this research, the stacked ceramic thin actuation layer with imbedded inter-digitated electrodes is designed and manufactured. The actuation strain of stacked ceramic thin actuation layer is measured and compared with the actuation strain of the LaRC-MFC. The comparison shows that the developed stacked ceramic thin actuation layer can
produce 10% more actuation strain than LaRC-MFC at relatively high electric field.
1175
Authors: Moh. Syaifuddin, Hoon Cheol Park, Kwang Joon Yoon, Nam Seo Goo
Abstract: This paper addresses detail design and demonstration of an insect-mimicking flappingwing mechanism composed of LIPCA (Lightweight Piezo-Composite Actuator) and linkage system that can amplify the actuation displacement of LIPCA. The angular amplification of the linkage system can provide various flapping angles by adjusting the actuation point of the LIPCA. The device can generate flapping frequency ranging from 5 to 50 Hz depending on weight of the wing and linkages. Flapping tests using different wing mass, area, and aspect ratio were performed to investigate the flapping performance. The test results were described and compared with the estimation. It was found that changes in wing mass, area, and aspect ratio result in significant variation of natural flapping-frequency.
1163
Authors: Yudi Heryawan, Hoon Cheol Park, Nam Seo Goo, Kwang Joon Yoon, Yung Hwan Byun
Abstract: This paper describes design, manufacturing, and wind tunnel test of a motor-driven
small-scale expandable wing for MAV class vehicles. The bird-like expandable wing has been developed for investigating the influence of aspect ratio change on the lift and drag of the wing. As a typical bird wing, the wing is separated into inner and outer wings. The wing model consists of the linkage system made of carbon composite strip/rod and the remaining part covered with carbon composite sheet and multiple LIPCAs (Lightweight Piezo-Composite Actuators) mimicking wing
feathers. The LIPCA actuator was used to control wing camber, which created additional lift. Wind tunnel tests were conducted to investigate the changes in lift and drag during wing folding and expansion, and to observe the influence of LIPCA actuation on the wing. In the tests, effects of the wing fold/expansion and actuation of LIPCA on changes in lift and drag were quantitatively identified.
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