• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.4
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• pp.451-460
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• 2014

In this paper, we examined the problem of the structural stability according to the patch load of a rectangular plate that reflects the material properties of A6082-T6 is used primarily for marine plant structure. it applied to the four patch loading shapes, the effect of aspect ratio, a boundary condition and calculated the critical elastic buckling load. Calculating the critical elastic buckling load, During the eigenvalue buckling analysis it is applied to the shell181 as 4 node shell element. when the plate subjected to patch loading compare to the plate under a uniform axial compression load, it is possible observed to occur the different elastic buckling behaviour and it could be confirmed that it is affected significantly on a variable position and type of loadings, such as the effect of the aspect ratio. Also, Critical elastic buckling load according to th patch loading type in simply supported rectangular plate a/b=1.0, ${\gamma}b$=200mm are calculated 67%(Loading type I), 119 %(Loading type II), 76 %(Loading type III), 160 %(Loading type IV), respectively. Loading type I and III could be determined with the strong elastic buckling behavior much more than Loading type II and IV.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.4
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• pp.17-26
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• 1991

Numerical methods are developed to obtain the critical loads and to analyze the post-buckling behaviour of the linearly varying tapered columns. The non-dimensional differential equations governing the elastica of post buckled column are derived by third order and solved numerically using the Runge-Kutta method and Regula-Falsi method. Three kinds of cross-sectional shape with simply supported end constraint are applied in unmerical examples. As the numerical results, the equlibrium paths. the typical elastica of post buckled columns and the critical load vs. section ratio curves are presented in figures. Also, the effects of cross-sectional shape factor on critical loads and postbuckling behaviour are presented in tables.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.865-873
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• 2013

This paper proposes a theoretical solution of elastic critical buckling load of infinitely long pipelines with non-uniform thickness under external pressure. The non-uniform cross section of pipelines can be considered as corroded or stiffened pipelines so that this paper can be a fundamental research of pipelines that are essential technology for offshore industries. The theoretical solution of pipelines with non-uniform thickness is derived with an assumption that a cylindrical shell under external pressure can be considered as a simple ring. The eigenfunctions are derived to obtain the critical buckling load. The reduced thickness and the reduced range are considered as variables in parametric analysis. The finite element analysis is performed to verify the theoretical solutions and the results of the analytic method and the finite element method are in good agreement.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.1
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• pp.399-405
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• 2012

This paper investigates the characteristics of buckling loads for steel arches with new type cross section which is consisted of T-section and pipe-section. A general purpose finite-element program ABAQUS was used to evaluate the inelastic buckling strengths of the arches which included the influence of the geometric and material nonlinearity. According to the comparisons between earlier studies and results from finite-element analyses, new design equations should be developed for the new arches. New buckling factors were developed to consider influence of rise-to-span ratio and boundary conditions. It is found that the presented factors are sufficiently accurate to predict the inplane buckling loads of new type section steel arches subjected to uniformly distributed loading. The proposed equations can be used to investigate new type steel arches subjected to unsymmetrical loading and composited arches.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.3
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• pp.193-198
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• 1981

Muskhelishvili 의 복소수방법에 의해 일반적 하중 즉 열 및 기계적 하중을 받는 무한 탄성체내에 공동을 가정하고 그 주위의 응력 및 변위를 유도하였다. 선형트랙(line rack)이 부분적으로 또는 완정히 닫힐 임계하중조건과 그때의 응력세기 계수 (stress intensity factor)를 McClintork와 Walsh 의 크랙닫힘에 관한 결정에 기초를 두고 해석학적으로 유도하였다.

• Computational Structural Engineering
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• v.11 no.3
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• pp.229-239
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• 1998

복합재료는 강도-무게비가 다른 재료들에 비해 훨씬 크기 때문에 부재의 좌굴문제가 대단히 중요하게 취급되며, 본 논문에서는 축방향 압축력을 받는 복합재료로 된 쉘 부재의 좌굴해석이 수행된다. 이 재료는 일반적으로 이방성 재료 특성을 나타내 보이나, 섬유들이 한 방향으로만 배치되어 있는 경우 섬유방향에 연직한 평면에서의 강도나 탄성계수들은 모두 일정한 횡 등방성 재료성질을 가진 것으로 간주할 수 있다. 9 절점 degenerate 쉘 유한요소를 사용한 선형안정해석, LUSAS 범용 프로그램을 이용한 구조해석, 그리고 고전적 쉘 좌굴방정식에 의한 해석들을 수행하였으며, 그 결과들을 서로 비교, 분석하였다. 고려된 등방성 재료나 횡 등방성 재료의 경우 모두, degenerate 유한요소해석으로 계산한 임계하중들은 고전적 이론해에 의한 결과들 보다 낮았으며, LUSAS 결과들과는 거의 같았다. 이는 degenerate 유한요소에 의한 선형안정해석 결과들이 안전측에 듬을 의미하며, 복합재료로 된 쉘 구조물의 좌굴해석에 degenerate 유한요소를 효율적으로 적용할 수 있음을 의미한다.

• Composites Research
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• v.15 no.3
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• pp.52-61
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• 2002

For the aerothermoelastic analysis of cylindrical piezolaminated shells, geometrically nonlinear finite elements based on the multi-field layerwise theory hale been developed. Applying a Han Krumhaar's supersonic piston theory, supersonic flutter analyses are performed for the cylindrical piezolaminted shells subject to thermal stresses and deformations. The possibility to increase flutter boundary and reduce thermoelastic deformations of piezolaminated panels is examined using piezoelectric actuations. Results show that active piezoelectric actuations can effectively increase the critical aerodynamic pressure by retarding the coalescence of flutter modes and compensating thermal stresses.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.1
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• pp.87-95
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• 2000

The two eigenvalues (elastic critical load and natural frequency of lateral vibration) of sinusoidally tapered bats with simply supported ends were determined by the finite element method. For the convenience of structural engineers who are engaged in the structural design or vibration analysis of tapered beam-columns, eigenvalue coefficients were expressed by simple algebraic equations. The validity of each algebraic equation was confirmed by the value of unity for each correlation coefficient. The influence of axial thrust on the lateral vibration frequency was also investigated. For this purpose, the axial thrust was increased successively and the corresponding frequency was calculated. The approximate linear relationship between the axial thrust and the square of the frequency was confirmed lot each of the tapered members.

• Journal of the Korea Concrete Institute
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• v.14 no.1
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• pp.58-66
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• 2002

The objective of this study is to examine the fracture characteristics of concrete at early ages such as critical stress intensity factor, critical crack-tip opening displacement, fracture energy, and bilinear softening curve based on the concepts of the effective-elastic crack model and the cohesive crack model. A wedge splitting test for Mode I was performed on cubic wedge specimens with a notch at the edge. By taking various strengths and ages, load-crack mouth opening displacement curves were obtained, and the results were analyzed by linear elastic fracture mechanics and the finite element method. The results from the test and analysis showed that critical stress intensity factor and fracture energy increased, and critical crack-tip opening displacement decreased with concrete ages from 1 day to 28 days. By numerical analysis four parameters of bilinear softening curve from 1 day to 28 days were obtained. The obtained fracture parameters and bilinear softening curves at early ages may be used as a fracture criterion and an input data for finite element analysis of concrete at early ages.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.594-600
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• 2021

Curved beam structures are generally used as components in structures such as railroad bridges and vehicles. The stability analysis of curved beams has been studied by a large number of researchers. Due to the complexities of structural components, it is difficult to obtain an analytical solution for any boundary conditions. In order to overcome these difficulties, the differential quadrature method (DQM) has been applied for a large number of cases. In this study, DQM was used to solve the complicated partial differential equations for buckling analysis of curved beams. The governing differential equation was deduced and solved for beams subjected to uniformly distributed radial loads. Critical loads were calculated with various opening angles, boundary conditions, and parameters. The results of the DQM were compared with exact solutions for available cases, and the DQM gave outstanding accuracy even when only a small number of grid points was used. Critical loads were also calculated for the in-plane inextensional buckling of the asymmetric curved beams, and two theories were compared. The study of a beam with extensibility of the arch axis shows that the effects on the critical loads are significant.