• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.602-604
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• 2011

본 연구에서는 알루미늄 폼 샌드위치 복합재료와 알루미늄 허니컴 샌드위치 복합재료의 면내 외 방향 압축실험으로 하중-변위의 관계를 분석하고 압축 특성을 비교하였다. 만능재료시험기로 1 mm/min 의 속도로 압축을 하였으며, 카메라로 실험과정을 촬영하고 로드셀에서 나오는 데이터를 컴퓨터로 저장하였다. 압축실험의 결과로 알루미늄 폼 및 허니컴 샌드위치 복합재료에서 하중이 증가함에 따라 심재에 좌굴이 발생하였다. 면내 방향 압축실험에서 알루미늄 폼 및 허니컴 샌드위치 시험편에 작용하는 압축 최대하중은 비슷하지만 비중을 고려하면 알루미늄 허니컴 샌드위치 복합재료가 더 우수한 것으로 판단되며, 면외 방향 압축실험에서도 알루미늄 허니컴 샌드위치 복합재료의 압축 최대하중이 알루미늄 폼 샌드위치 복합재료보다 높게 나왔다.

• Journal of Korean Society of Steel Construction
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• v.18 no.3
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• pp.301-310
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• 2006

If arches are braced by lateral restraints, the ultimate strength of arches is determined by in-plane buckling and plastic bending collapse. This paper is conducted to investigate the in-plane nonlinear elastic and inelastic buckling behavior and the strength of fixed parabolic arches in uniform compresion, as well as to study arch behaviors against non-uniform in-plane compression and bending. As shown by the results, the limit slenderness ratio is suggested to classify the bucklingmode. Buckling strength of fixed parabolic arches under uniform compresion are evaluated using buckling curve for a straight column. Finally, an interaction e quation for arches under combined axial compresion and bending action is proposed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.191-203
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• 2006

The vibration characteristics of composite stiffened laminated plates with stiffener is presented using the assumed natural strain 9-node shell element. To compare with previous research, the stiffened plates are composed of carbon-epoxy composite laminate with a symmetric stacking sequence. Also, the result of the present shell model for the stiffener made of composite material is compared with that of the beam model. In the case of torsionally weak stiffener, a local buckling occurs in the stiffener. In this case, the stiffener should be idealized by using the shell elements. The current investigation concentrates upon the vibration analysis of rectangular stiffened and unstiffened composite plates when subjected to the in-plane compression and shear loads. The in-plane compression affect the natural frequencies and mode shapes of the stiffened laminated composite plates and the increase in magnitude of the in-plane compressive load reduces the natural frequencies, which will become zero when the in-plane load is equal to the critical buckling load of the plate. The natural frequencies of composite stiffened plates with shear loads exhibit the higher values than the case of without shear loads. Also, the intersection, between the curves of frequencies against in-plane loads, interchanges the sequence of some of the mode shapes as a result of the increase in the inplane compressive load. The results are compared with those available in the literature and this result shows that the present shell model for the stiffened plate gives more accurate results. Therefore, the magnitude, direction type of the in-plane shear and compressive loads in laminated composite stiffened plates should be selected properly to control the specific frequency and mode shape. The Lanczos method is employed to solve the eigenvalue problems.

• Computational Structural Engineering
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• v.11 no.4
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• pp.239-251
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• 1998

본 연구에서는 비대칭 박벽단면을 갖는 곡선보의 안정성해석을 수행할 수 있는 이론 및 엄밀해를 제시하기 위하여, 3차원 연속체로부터 유도된 평형방정식으로부터 선형화된 가상일의 원리를 적용하였다. 박벽단면의 구속된 ？(warping)과 곡률효과를 고려하고 유한한 회전각의 2차항을 포함하는 곡선보의 변위장을 도입하여 단면에 대해 적분함으로써 도심축에 대한 박벽 곡선보의 총포텐셜에너지를 유도하였다. 또한, 단순지지되고 일축대칭 단면을 갖는 박벽원형 곡선보의 면내 및 면외좌굴에 대한 엄밀해를 유도하기 위하여, 면내에 대해서는 균일압축을 받는 원형아치의 역대칭 좌굴모드에 대한 좌굴하중을 유도하고 면외좌굴에 대해서는 균일압축 및 순수휨을 받는 아치의 처짐함수를 가정하여 곡선보의 횡좌굴하중에 대한 일반해를 제시하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2002.11a
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• pp.107-112
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• 2002

Basically, ship structure consists of the plate members, and a strength of overall ship structurnds on the stiffness and strength of ship platings. If buckling which causes to deflect ship plate members occurs, the stiffness of ship plate markedly decreases, and thus buckling has a serious effect on the stiffness or strength of overall ship structure. Buckling is one of the most important design criteria when we scantle structure members. In the present study, a inplane rigidity of a compressed ship plate above buckling load is proposed. The proposed inplane rigidity is available in the elastic or elasto-Plastic ranges in order to can out a more efficient and reliable design.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.3802-3807
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• 2011

In this study, in-plane and out-plane compression tests of aluminum foam and honeycomb sandwich composites were carried out. Through these tests, the relationships of load-displacements were analyzed and the compression characteristics were compared with each other. The specimens were compressed with the speed of 1mm/min by using the universal testing machine. Experimental procedures were taken with photograph by the camera and load cell data were stored into computer. Test results showed that buckling was occurred at the aluminum foam core and honeycomb core according to the increase of load. In the in-plane compression test, the maximum load of aluminum foam specimen was similar with that of honeycomb sandwich. The property of honeycomb was better than that of the foam in consideration of specific gravity. In the out-plane compression test, compression maximum load of aluminum honeycomb sandwich composite was higher than that of aluminum foam sandwich composite.

• Journal of Ocean Engineering and Technology
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• v.15 no.1
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• pp.85-91
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• 2001

A study for the structural strength analysis on the doubler plate subjected biaxial in-plane compression and shear load has been performed through the systematic evaluation process. In order to estimate the proper static strength of the doubler plate, non-linear elasto-plastic analysis is introduced. Gap element modeling for contact effect between the main plate and the doubler is prepared and nonlinear analysis procedures are illustrated based on MSC/N4W. In addition, some design guides are suggested through the consideration of several important effects such as corrosion of main plate, doubler width, doubler length and doubler thickness. Finally, theses result are compared with a developed design formula based on the buckling strength and general trends. The design guides, according to the variation of design parameters are discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.5199-5206
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• 2010

In this paper, we investigate the buckling analysis of laminated composite plates, using a improved assumed natural strain shell element. In order to overcome membrane and shear locking phenomena, the assumed natural strain method is used. The eigenvalues of the laminated composite plates are calculated by varying the width-thickness ratio and angle of fiber. To improve an shell element for buckling analysis, the new combination of sampling points for assumed natural strain method was applied and the refined first-order shear deformation theory which allows the shear deformation without shear correction factor. In order to validate the present solutions, the reference solutions are used and discussed. The results of laminated composite plates under the in-plane shear loading may be the benchmark test for the buckling analysis.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.597-605
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• 2009

The present study has been proposed a model for the in-plane shear behavior of reinforced(Engineered Cementitious Composite(ECC) panels under biaxial stress states. The model newly considers the high-ductile tensile characteristic of cracked ECC by its multiple micro-cracking mechanism, the compressive strain-softening characteristic of cracked ECC, and the shear transfer mechanism in the cracked interface of ECC element. A series of numerical analyses were performed, and the predicted curves were compared with experimental results. The proposed in-plane shear model, R-ECC-MCFT, was found to be well matched with the experimental results, and it was also demonstrated that reinforced ECC panel showed more improved in-plane shear strength and post peak behavior, in comparing with the conventional reinforced concrete panel.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.1 s.16
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• pp.55-62
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• 2005

Parabolic arch ribs are widely used in practical. In case of circular arch ribs. Inelastic in-plane buckling behaviors were investigated by Trahair(1996). Recently Yong-lin Pi & Bradford(2004) investigated about in-plane design equation for circular arch ribs. In $1970{\sim}1980$. In-plane buckling strength about parabolic arch ribs were studied by some japan researchers (Sinke, Kuranishi). Study results of Sinke & kuranishi are only valid for rise-span ratio $0.1{\sim}0.2$. In this paper. The researchers investigated about in-plane inelastic buckling behaviors of parabolic arch ribs having rise-span ratio from 0.1 to 0.4. From the results. When the rise-span ratio increase, flexural moments increase and influence of axial force to in-plane buckling strength decrease. Finally, buckling curves for parabolic arch ribs subjected distributed loading along the axis were suggested.