• 한국소음진동공학회논문집
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• 제23권10호
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• pp.928-934
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• 2013

In this paper, the vibration characteristics of the trapezoidally corrugated plate are investigated by the analytical method. The corrugated plate is widely used as the structural elements because of its high stiffness and light weight. Because the corrugated plate is flexible in the corrugation direction and stiff in the transverse direction, it is treated as an equivalent orthotropic plate to analyze the corrugated plate simply. This equivalent plate must include both extensional and flexural effect to obtain the precise solution. The effective extensional and flexural stiffness of the equivalent plate are derived to consider these effects in the analysis. To demonstrate the validity of the proposed approach, the comparison is made with the previously published results and ANSYS solutions. Some numerical results are presented to check the effect of the geometric properties.

• 동력기계공학회지
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• 제18권1호
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• pp.99-105
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• 2014

In this paper, the static characteristics of the trapezoidal corrugated plate under uniformly distributed pressure are investigated by the analytical method. Because the corrugated plate is very flexible in the corrugation direction and stiff in the transverse direction, the corrugated plate is treated as the orthotropic plate. This equivalent orthotropic plate must include both the extensional and flexural effect to obtain the precise solution. The effective extensional and flexural stiffness of the trapezoidal corrugated plate are derived to consider these effects in the analysis. To demonstrate the validity of the proposed approach, the comparison is made with the previously published results. Some numerical results are presented to check the effect of the geometric properties.

• 한국산학기술학회논문지
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• 제18권11호
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• pp.762-769
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• 2017

준등방성 라미네이트내의 확장강성 계수는 방사방향으로균일하지만, 굽힘강성 계수는 플라이 적층순서에 의해 방사방향으로 변화한다. 이 논문에서는 복합재 광학에서 사용되는 단방향섬유 복합재료와 무작위로 분포된 단섬유 복합재료로 이루어진 세 가지 유형의 준 등방성 라미네이트 반사경내의 굽힘강성 계수의 방사방향의 변화량을 비교하였다. 단섬유 복합재료 반사경 방사방향의 확장강성 계수와 굽힘강성 계수는 균일하게 나타나는 반면, 단방향섬유 복합재료 반사경의 경우에는 굽힘강성 계수의 방사방향으로의변화량이 11%에서 많게는 26%까지 변화하는 것으로 나타났다. 또한 강성계수의 차이로 인한 굽힘-비틀림-커플링 효과 등 강성 민감도 또한 큰 것으로 나타났다. 이러한 요소는 정밀성이 요구되는 광학분야에 복합재 반사경의 적용을 어렵게 할 커다란 문제점으로 인식되며, 이러한 복합재료의 이방성 성질로 인한 필연적인방사형 방향으로의 강성계수의 변화 및 그 영향성을 줄이기 위해서는 단섬유나 무작위로 공간에 흩어져있는 섬유 복합재료를 사용하는 것이 복합재 반사경내에 존재하는 굽힘강성 계수의 변화를 제거하는 하나의 방법이다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 봄 학술발표회 논문집
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• pp.243-250
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• 2004

This paper reports on the evaluation of the initial stiffness of steel joints using component method as well as experimental tests. The so-called component method corresponds precisely to a simplified mechanical model composed of extensional springs and rigid links, whereby the joint is simulated by an appropriate choice of rigid and flexible components. An application to a cantilever beam-to-column steel joint is presented and compared to the experimental results obtained under cyclic loading condition. Comparison between numerical and experimental results allows to conclude that the numerical model is able to simulate, with a good level of accuracy for initial stiffness, the behaviour of beam-to-column joints.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 춘계학술발표대회 논문집
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• pp.120-125
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• 2000

A heddle frame is the major part of a loom that produces woven cloth by insertion of weft yarns between warp yams. Warp yarns are manipulated by many heddles fixed in a heddle frame. Recently, the up and down speed of heddle frames has been increased much for the increase of productivity, which induces higher inertial stresses and vibrations in the heddle frame. The heddle frame has the rectangular cross-section. For the design of box type beams of rectangular cross-section, extensional stiffness EA, flexural stiffness El, and torsional stiffness GJ as well as the vibration characteristics are important and should be simultaneously considered. Tn this paper, the vibration characteristics of the composite and the composite sandwich beams for high-speed heddle frame were tested by impulse frequency response.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.1-4
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• 2001

A new non-destructive fatigue prediction model of the composite laminates is developed. The natural frequencies of fatigue-damaged laminates under extensional loading are related to the fatigue lift of the laminates by establishing the equivalent flexural stiffness reduction as a function of the elastic properties of sublaminates. The flexural stiffness is derived by relating the $90^{\circ}$-ply elastic modulus reduction, and using the laminate plate theory to the degraded elastic modulus and the intact elastic modulus of other laminate. The natural frequency reduction model, in which the dominant fatigue mode can be identified from the sensitivity scale factors of sublaminate elastic properties, provides natural frequency vs. fatigue cycle curves for the composite laminates. Vibration tests were also conducted on $[\textrm{90}_{2}\textrm{0}_{2}]_s$ carbon/epoxy laminates to verify the natural frequency reduction model. Correlations between the predictions of the model and experimental results are good.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.407-413
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• 2001

A modeling method for the vibration analysis of rotating composite cantilever plates is presented. Explicit mass and stiffness matrices are derived by considering the coupling effects between extensional motions and the bending motion, To confirm the accuracy of the method presented in this study, numerical results are obtained and compared to those of a commercial program. Numerical results show that the coupling effect among the three motions becomes important for the accurate estimation of natural frequencies as laminates are stacked up unsymmetrically. Also, natural frequencies loci veering, loci crossing, and mode shape variations are observed.

• 한국소음진동공학회논문집
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• 제26권7호
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• pp.851-856
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• 2016

In this paper, the free vibration characteristics of longitudinally corrugated cylindrical shells is investigated by the theoretical analysis. The equivalent homogenization model is adapted to investigate the overall mechanical behavior of these corrugated shells. The corrugated element can be represented as an orthotropic material. Both the effective extensional and flexural stiffness of this equivalent orthotropic material are considered in the analysis. To demonstrate the validity of the proposed theoretical approach, the theoretical results are compared with those from 3D finite element analysis using ANSYS commercial code. Some numerical results are presented to check the effect of the geometric properties.

• Structural Engineering and Mechanics
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• 제53권1호
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• pp.159-172
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• 2015

This paper is concerned with effects of the wall flexibility on the seismic behavior of ground-supported cylindrical silos. It is a well-known fact that almost all analytical approximations in the literature to determine the dynamic pressure stemming from the bulk material assume silo structure as rigid. However, it is expected that the horizontal dynamic material pressures can be modified due to varying horizontal extensional stiffness of the bulk material which depends on the wall stiffness. In this study, finite element analyses were performed for six different slenderness ratios according to both rigid and flexible wall approximations. A three dimensional numerical model, taking into account bulk material-silo wall interaction, constituted by ANSYS commercial program was used. The findings obtained from the numerical analyses were discussed comparatively for rigid and flexible wall approximations in terms of the dynamic material pressure, equivalent base shear and bending moment. The numerical results clearly show that the wall flexibility may significantly affects the characteristics behavior of the reinforced concrete (RC) cylindrical silos and magnitudes of the responses under strong ground motions.

• 한국산학기술학회논문지
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• 제19권11호
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• pp.750-757
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• 2018

보강토교대는 보강토옹벽을 교대로 활용하는 토류구조물로써, 보강토체의 변형을 억제하기 위해, 마찰성능이 우수한 채움재와 비신장성 금속 보강재를 사용하고 있다. 본 연구에서는 보강토교대에 주로 사용되는 비신장성 금속 보강재에 대한 인발거동을 분석하기 위하여, 보강토교대 채움재의 강성 및 입도분포와 보강재의 간격에 따른 인발거동을 검토하였다. 매개분석을 통한 분석결과, 보강토체의 인발력은 최상단 보강재에 가장 크게 작용하였고, 보강토교대의 채움재의 특성과 보강재의 수평간격도 보강토의 인발저항에 큰 영향을 미치는 것으로 나타났다. 채움재의 내부마찰각은 최소 25도 이상, 균등계수는 4 이상의 사질토 그리고 최상단 보강재의 수평간격은 25cm 이하로 배치해야만 설계기준에 제시된 최소 인발 안전율을 만족하였다. 따라서, 보강토체의 인발저항성능을 확보하기 위해서는 채움재의 특성을 면밀하게 고려하여 설계를 수행하여야 하며, 채움재의 특성뿐만 아니라 하중조건을 고려하여 보강재의 배치도 적절하게 하여야 할 것이다. 시공시에는 설계시 고려한 채움재의 강성과 입도분포에 대한 철저한 품질 및 시공 관리가 필요할 것이다.