• 센서학회지
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• 제29권4호
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• pp.261-265
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• 2020

In cantilever type piezoelectric energy harvester, the amount of power generation decreases rapidly when outside a certain frequency. The thickness and weight of the cantilever metal plate were modified to develop cantilevers that could produce high power over a wide frequency range. The thicker the cantilever, the higher the power in the higher frequency range. As the weight of the mass increased, the cantilever tended to generate higher power, and the frequency band decreased. A 0.6 mm metal plate cantilever that had a mass of 3.3 g generated power that exceeded 3 mW within the 91-102 Hz range, with average and output values of 9.484 mW and 20.748 mW, respectively, at 99 Hz.

• Structural Engineering and Mechanics
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• 제6권8호
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• pp.939-953
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• 1998

Vibration, buckling and dynamic stability of a cantilever rectangular plate subjected to an in-plane sinusoidally varying load applied along the free end are analyzed. The thin plate small deflection theory is used. The Rayleigh-Ritz method is employed to solve vibration and buckling of the plate. The dynamic stability problem is solved by using the Hamilton principle to drive time variables. The resulting time variables are solved by the harmonic balance method. Buckling properties and natural frequencies of the plate are shown at first. Unstable regions are presented for various loading conditions. Simple parametric resonances and combination resonances with sum type are obtained for various loading conditions, static load and damping.

• Journal of the Korean Wood Science and Technology
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• 제42권5호
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• pp.571-578
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• 2014

As a way of developing wooden joint development, a glass fiber reinforced wood plate was manufactured to replace a steel plate. Also, the fracture toughness was evaluated. Through application to a cantilever-type specimen made of a column and a beam, the moment resistance performance was evaluated. For the fracture toughness specimen of the wood plate, 12 types were manufactured by varying the combination of a main member (veneer and plywood) and reinforcement (glass fiber sheet and glass fiber cloth). The results of the fracture toughness test indicated that the 5% yield load of the specimen using plywood was 18% higher than that of the specimen using veneer, and that the specimen reinforced by inserting glass fiber sheets between testing materials (Type-3-PS) had the highest average 5% yield load 4841 N. Thus, a moment resistance strength test was performed by applying Type-3-PS to a column-beam joint. The results of the test indicated that compared to the specimen using a steel plate and a drift pin (Type-A), the maximum moment ratio of the specimen using a glass fiber reinforced wood plate (Type-3-PS) and a drift pin (Type-B) was 0.79; and that a rupture occurred in the wood plate due to high stiffness of the drift pin. The maximum moment ratio of the specimen using a glass fiber reinforced wood plate (Type-3-PS) and a glass fiber reinforced wooden laminated pin (Type-C) was 0.67, which showed low performance. However, unlike Type-A, a ductile fracture occurred on Type-C, and the load gradually decreased even after the maximum moment.

• Structural Engineering and Mechanics
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• 제88권2호
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• pp.189-200
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• 2023

Silicate glass is usually a brittle and plate-like material, and it is difficult to measure the elastic modulus by the traditional method. This paper develops a test method for the glass elastic modulus based on the fundamental frequency of the cantilever beam with an elastic support and a free end. The method installs the beam-type specimen on a semi-rigid support to form an elastic support-free end beam. The analytic solution of the stiffness coefficients of the elastic support is developed by the fundamental frequency of the two specimens with known elastic modulus. Then, the glass elastic modulus is measured by the fundamental frequency of the specimens. The method significantly improves the measurement accuracy and is suitable for the elastic modulus with the beam-type specimen whether the glass is homogeneous or not. Several tests on the elastic modulus measurement are conducted to demonstrate the reliability and validity of the test method.

• 대한기계학회논문집A
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• 제30권4호
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• pp.409-419
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• 2006

The actuating performance of plate-type unimorph piezoelectric composite actuators having various stacking sequences was evaluated by three dimensional finite element analysis on the basis of thermal analogy model. Thermal residual stress distribution at each layer in an asymmetrically laminated plate with PZT ceramic layer and thermally induced dome height were predicted using classical laminated plate theory. Thermal analogy model was applied to a bimorph cantilever beam and LIPCA-C2 actuator in order to confirm its validity. Finite element analysis considering thermal residual deformation showed that the bending behavior of piezoelectric composite actuator subjected to electric loads was significantly different according to the stacking sequence, thickness of constituent PZT ceramic and boundary conditions. In particular, the increase of thickness of PZT ceramic led to the increase of the bending stiffness of piezoelectric composite actuator but it did not always lead to the decrease of actuation distance according to the stacking sequences of piezoelectric composite actuator. Therefore, it is noted that the actuating performance of unimorph piezoelectric composite actuator is rather affected by bending stiffness than actuation distance.

• 한국철도학회논문집
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• 제3권2호
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• pp.43-50
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• 2000

The corrugated panels are the prime candidate structure for the floor, roof and wall of Korean high speed train. The equivalent continuum modeling approach panels can be used for the efficient design and evaluation of their structural characteristics. The equivalent continuum models, derived from the true complex corrugated panels, should have the same structural behavior as the original structures have. This paper briefly reviews three representative continuum modeling methods: the static analysis method and two plate-models based on modal analysis methods (MAM). These methods are evaluated through some numerical examples by comparing the natural frequencies and static deflections. It is observed that the plate-model based on Rayleigh-Ritz method seems to provide the best results when used in conjunction with the cantilever-type boundary conditions. The equivalent elastic constants of various corrugated panels, depending on the changes in their configurations, are tabulated for efficient use in structural design.

• 한국전산구조공학회논문집
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• 제19권4호
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• pp.399-406
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• 2006

황동 개재물이 있는 Al 정사각판의 고유진동수는 혼합법칙을 이용하여 해석되었다. 혼합법칙에 의한 고유진동수는 개재물의 크기에 따른 유효 내평면 파동속도와 무차원 진동수 매개변수와의 곱으로 이루어진다. 해석모델은 외팔형, 2변 고정-2변 자유형, 3변 고정-1변 자유형 및 4변 고정형의 황동 개재물이 있는 4가지의 Al판이다. 자유단이 1개 이상 존재하는 경계조건에서 개재물이 판의 중앙에 위치하였을 때 개재물에 대한 판 전체의 면적비가 1/9 이하이면 혼합법칙 및 유한요소 해석에 의한 고유진동수는 10% 이내로 잘 일치하였다 4변 고정형 경계조건을 제외하고 3가지 경계조건에서 개재물이 판중앙에 있을 경우 개재물의 크기가 커짐에 따라 개재물이 있는 판의 고유진동수는 낮아짐을 알았다. 또한 개재물의 밀도가 판의 밀도보다 작을 때, 개재물 크기가 커짐에 따라 개재물이 있는 판의 고유진동수는 높아진다.

• 한국해양공학회지
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• 제13권3호통권33호
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• pp.57-67
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• 1999

Welding is widely applicable and reliable process and is mainly adopted for fabricating heavy structures. Recently, weld metal transverse cracks in butt and fillet weld joint is a serious problem, and they must be eliminated for improving weld joint reliability. The weld metal transverse crack susceptibility of butt and fillet joint was carried out by cantilever type tensile crack testing jig and CTS test. In this view of point, this study investigated the potential factors for weld metal transverse crack. The main results obtained were as follows: 1. The content o fdiffusible hydrogen in weld metal played an important role for weld metal transverse cracks. 2. From cantilever type tensile crack tests, it was pointed out that the higher the diffusible hydrogen content and tensile restraint, the more susceptible to weld metal transverse craking. 3. The TSN(thermal severity number) and diffusible hydrogen were important factors for determining weld metal transverse cracks in fillet weld joints.

• Journal of the Korean Wood Science and Technology
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• 제43권1호
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• pp.60-67
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• 2015

국내산 낙엽송 집성재와 봉형 GFRP의 접착성능을 평가하기 위해 집성재에 선공을 한 후 봉형 GFRP를 삽입하고 접착제로 목재와의 간극을 충진시켜 인발시험편을 제작하였다. 인발시험편은 접착 깊이, 접착층 두께, 접착제 종류를 다르게 적용하여 실험하였다. 봉형 GFRP를 삽입접착한 캔틸레버형 라멘구조 시험체는 인발시험 결과를 토대로 제작, 강판삽입형 시험체와 모멘트 저항 성능을 비교검토 하였다. 인발시험결과 봉형 GFRP의 삽입깊이가 봉형 GFRP 직경의 5배일 때 가장 우수한 접착력이 측정되었으며, 접착층 두께는 1 mm일 경우 2 mm일 때보다 17%~29% 향상된 접착력이 측정되었다. 또한 폴리우레탄(poly-urethane) 접착제를 사용한 시험편이 레조시놀(resorcinol) 접착제를 사용한 시험편보다 2.9~4.0배 높은 성능을 발휘하였다. 봉형 GRFP로 접합한 캔틸레버형 라멘구조 시험체는 드리프트 핀을 사용한 강판삽입형 시험체와 비교하여 평균 0.82배 낮은 모멘트 저항 성능이 측정되었지만 초기강성은 0.93배로 대등한 성능을 보였다.

• 대한기계학회논문집
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• 제8권3호
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• pp.232-240
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• 1984

본 논문에서는 Stern이 제시한 경로적분식을 기본방정식으로 하여 예리한 임 의 노치내각을 가진(크랙의 경우 0˚), 즉 r$^{.lambda.}$ 형태의 특이점을 포함한 모우드-I 및 II 응력확대계수를 위한 특성해 및 보조해를 규정하고 선택모형문제로 예리한 노치 내각을 달리한 대칭 하중의 인장문제와 끝단 전단력하중하의 일단 고정보의 비대칭문 제의 응력확대계수를 기존의 재래식 유한요소법과 결합하여 계산하였다. 또한 각각 의 경우 적분경로 및 요소분할을 달리하여 수치해의 안정성 및 경로 독립성을 검토하 였다.