• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.246-249
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• 2004

A smart material is used as spectacle frames and brassiere frames, and partly in medical supplies because of its shape memory effect. The smart composite can be used on the wing of an airplane instead of the existing aluminium to control crack propagation. In this study, the smart composite was fabricated by a hot press method. TiNi alloy as reinforcement and A16061 as matrix were used, respectively. The mechanical properties of the smart composite under thermal shock cycles were evaluated. In addition, Acoustic Emission techniques were also used to clarify the damage behavior of the smart composite under thermal shock cycles nondestructive.

• 비파괴검사학회지
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• 제27권4호
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• pp.328-338
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• 2007

스마트 재료를 이용한 복합재료의 가장 큰 장점 중의 하나는 재료내부에 발생한 균열을 제어하는데 있다. 구조용 재료로 사용 중에 구조물 내에 균열이 발생할 때 균열의 진전을 억제할 수 있는 방법 중의 하나가 형상기억합금재료의 형상기억효과를 이용하는 것이다. 본 연구에서는 최적의 제조조건을 도출하여 형상기억합금을 이용한 형상기억복합재료를 제조하였다. 또한 형상기억복합재료 내부의 형상기억합금에 의한 형상기억효과를 평가하기 위하여 복합재료에 인장하중을 가하여 복합재료에 발생하는 응력분포를 평가하고 복합재료에 열을 가하여 형상기억합금을 원래의 상태로 복귀하면서 복합재료 전체의 응력변화를 평가하였다. 형상기억복합재료의 인장하중에 따른 응력분포를 관찰하기 위하여 광탄성에 의한 가시화 장치를 이용하였다.

• Composites Research
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• 제28권2호
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• pp.52-57
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• 2015

Soft morphing robotics making use of smart material and based on biomimetic principles are capable of continuous locomotion in harmony with its environment. Since these robots do not use traditional mechanical components, they can be built to be light weight and capable of a diverse range of locomotion. This paper illustrates a flexible smart phone robot made of smart soft composite (SSC) with inchworm-like locomotion capable of two-way linear motion. Since rigid components are embedded within the robot, bending actuators with embedded rigid segments were investigated in order to obtain the maximum bending curvature. To verify the results, a simple mechanical model of this actuator was built and compared with experimental data. After that, the flexible robot was implemented as part of a smart phone robot where the rigid components of the phone were embedded within the matrix. Then, experiments were conducted to test the smart phone robot actuation force under different deflections to verify its load carrying capability. After that, the communication between the smart phone and robot controller was implemented and a corresponding phone application was developed. The locomotion of the smart phone robot actuated through an independent controller was also tested.

• 센서학회지
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• 제8권6호
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• pp.440-447
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• 1999

지능형 복합재료 구조물(Smart Composite Structures) 사용 시 부하되는 인장하중과 복합재료의 경화 시 발생하는 열하중은 복합재료 내에 삽입된 광섬유 센서의 기계적 거동에 직접적인 영향을 미친다. 게다가 복합재료의 적층 순서 및 코팅층의 유무에 따라 광섬유 센서 내의 웅력 분포는 달라지게 된다. 또한, 복합재료 적층판 내에서 발생된 균열은 적층판 전체의 파괴뿐만 아니라 광섬유 센서의 파괴에 큰 영향을 미치게 된다. 그러므로, 본 연구에서는 인장하중 및 열하중이 가해지는 복합재료 적층판 내에 삽입된 광섬유 센서의 응력분포를 유한요소해석을 통해 알아보고, 복합재료 적층판의 적층 순서에 따른 영향과 광섬유 센서에 코팅을 하였을 경우 광섬유 센서 내의 응력분포에 미치는 영향을 알아보았다. 또, 인장실험을 통하여 적층판 내에서 발생한 균열이 광섬유 센서의 파괴에 미치는 영향을 알아보았다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.51-54
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• 2005

Shape memory alloys (SMAs) find many applications in smart composite structural systems as the active components. Their ability to provide a high force and large displacement makes them an excellent candidate for an actuator for controlling the shape of smart structures. In this paper, using a macroscopic model that captures the thermo-mechanical behaviors and the two-way shape memory effect (TWSME) of SMAs smart morphing polymeric composite shell structures like shape-changeable UAV wings is demonstrated and analyzed numerically and experimentally when subjected to various kinds of pressure loads. The controllable shapes of the morphing shells to that thin SMA strip actuator are attached are investigated depending on various phase transformation temperatures. SMA strips start to transform from the martensitic into the austenitic state upon actuation through resistive heating, simultaneously recover the prestrain, and thus cause the shell structures to deform three dimensionally. The behaviors of composite shells attached with SMA strip actuators are analyzed using the finite element methods and 3-D constitutive equations of SMAs. Several morphing composite shell structures are fabricated and their experimental shape changes depending on temperatures are compared to the numerical results. That two results show good correlations indicates the finite element analysis and 3-D constitutive equations are accurate enough to utilize them for the design of smart composite shell structures for various applications.

• 동력기계공학회지
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• 제13권1호
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• pp.65-71
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• 2009

To address the need for new intelligent sensing, this paper introduces nano sensors made of carbon nanotube (CNT) composites and presents their preliminary experiments. Having smart material properties such as piezoresistivity, chemical and bio selectivity, the nano composite can be used as smart electrodes of the nano sensors. The nano composite sensor can detect structural deterioration, chemical contamination and bio signal by means of its impedance measurement (resistance and capacitance). For a structural application, the change of impedance shows specific patterns depending on the structural deterioration and this characteristic is available for an in-situ multi-functional sensor, which can simultaneously detect multi symptoms of the structure. This study is anticipated to develop a new nano sensor detecting multiple symptoms in structural, chemical and bio applications with simple electric circuits.

• Structural Engineering and Mechanics
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• 제12권2호
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• pp.135-156
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• 2001

Analytical solutions and finite element results of laminated composite plates with smart material layers embedded in them are presented in this study. The third-order plate theory of Reddy is used to study vibration suppression characteristics. The analytical solution for simply supported boundary conditions is based on the Navier solution procedure. The velocity feedback control is used. Parametric effects of the position of the smart material layers, material properties, and control parameters on the suppression time are investigated. It has been found that (a) the minimum vibration suppression time is achieved by placing the smart material layers farthest from the neutral axis, (b) using thinner smart material layers have better vibration attenuation characteristics, and, (c) the vibration suppression time is larger for a lower value of the feedback control coefficient.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.251-257
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• 1999

Smart structure that contains sensors, which are either embedded in a composite material or attached to a structure, is currently receiving considerable attention. Fiber Bragg grating sensor, one of the optical fiber sensors, has been widely used to sense strain and temperature for smart structures since both parameters change the resonant frequency of the grating. In this paper, according to the various heating and cooling conditions the thermal behavior of unidirectional composite material was monitored by embedding the fiber Bragg grating sensors in the longitudinal and transverse directions of unidirectional composites. The thermal behavior of unidirectional composite material was monitored for various heating and cooling rates and applied pressure. It was found that the thermal behavior was unaffected by pressure variations and heating and cooling rates applied to the composites. The thermal strains were measured by considering the shift in Bragg wavelength that was generated by the thermal expansion of composite specimen. The longitudinal and transverse C.T.E.'s were also obtained from the corresponding temperature-thermal strain curves.

• 한국초전도ㆍ저온공학회논문지
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• 제24권1호
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• pp.8-12
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• 2022

Recently, research on applying composite materials to various industrial fields is being actively conducted. In particular, composite materials fabricated by Fused Deposition Modeling 3D printers have more advantages than existing materials as they have fewer restrictions on manufacturing shape, reduce the time required, weight. With these advantages, it is possible to consider utilizing composite materials in cryogenic environments such as the application of liquid oxygen and liquid hydrogen, which are mainly used in an aerospace and mobility. However, FDM composite materials are not verified in cryogenic environments less than 150K. This study evaluates the characteristics of composite materials such as tensile strength and strain using a UTM (Universal Testing Machine). The specimen is immersed in liquid nitrogen (77 K) to cool down during the test. The specimen is fabricated using 3D print, and can be manufactured by stacking reinforced fibers such as carbon fiber, fiber glass, and aramid fiber (Kevlar) with base material (Onyx). For the experimental method and specimen shape, international standards ASTM D638 and ASTM D3039 for tensile testing of composite materials were referenced.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.42-45
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• 2001

The characteristics of smart skin for wireless LAN system under compression load are investigated. The smart skin structure is composed of 3 layers of face material and 2 layers of core material. Theoretical formula for determining buckling load is derived by Rayleigh-Ritz method and compared with experimental result. The maximum length of specimen that buckling does not occur is determined by only face material. In the experiment, if load supporting capability and the antenna property such as radiation pattern and reflection coefficient were examined.