• Structural Engineering and Mechanics
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• 제32권2호
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• pp.301-320
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• 2009

Damage assessment for buried structures against an internal blast is conducted by considering the soil-structure interaction. The structural element under analysis is assumed to be rigid-plastic and simply-supported at both ends. Shear failure, bending failure and combined failure modes are included based on five possible transverse velocity profiles. The maximum deflections with respect to shear and bending failure are derived respectively by employing proper failure criteria of the structural element. Pressure-Impulse diagrams to assess damage of the buried structures are subsequently developed. Comparisons have been done to evaluate the influences of the soil-structure interaction and the shear-to-bending strength ratio of the structural element. A case study for a buried reinforced concrete structure has been conducted to show the applicability of the proposed damage assessment method.

• Structural Engineering and Mechanics
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• 제33권3호
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• pp.307-323
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• 2009

This article presents the differential system that governs the mechanical behaviour of a curved-beam element, with varying cross-section area, subjected to generalized load. This system is solved by an exact procedure or by the application of a new numerical recurrence scheme relating the internal forces and displacements at the two end-points of an increase in its centroid-line. This solution has a transfer matrix structure. Both the stiffness matrix and the equivalent load vector are obtained arranging the transfer matrix. New structural matrices have been defined, which permit to determine directly the unknown values of internal forces and displacements at the two supported ends of the curved-beam element. Examples are included for verification.

• Nuclear Engineering and Technology
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• 제39권1호
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• pp.75-84
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• 2007

This paper presents a closed-form model for evaluating the restraint effect of pressure induced bending on the opening of a circumferential through-wall crack, which is considered plastic deformation behavior. Three-dimensional finite element analyses with different crack lengths, restraint conditions, pipe geometries, magnitudes of internal pressure, and tensile properties were used to investigate the influence of each parameter on the pressure-induced bending restraint on the crack opening displacement. From these investigations, an analytical model based on elastic-perfectly plastic material was developed in terms of the crack length, symmetric restraint length, mean radius to thickness ratio, axial stress corresponding to the internal pressure, and normalized crack opening displacement evaluated from a linear-elastic crack opening condition. Finite element analyses results demonstrate that the proposed analytical model reliably estimated the restraint effect of pressure-induced bending on the plastic crack opening of a circumferential through-wall crack and properly reflected the dependence on each parameter within the range over which the analytical expression was derived.

• Advances in nano research
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• 제12권4호
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• pp.405-414
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• 2022

In this study, the elastic plane problem of a layered composite containing an internal or edge crack perpendicular to its boundaries in its lower layer is examined using numerical analysis. The layered composite consists of two elastic layers having different elastic constants and heights. Two bonded layers rest on a homogeneous elastic half plane and are pressed by a rigid cylindrical stamp. In this context, the Finite Element Method (FEM) based software called ANSYS is used for numerical solutions. The problem is solved under the assumptions that the contacts are frictionless, and the effect of gravity force is neglected. A comparison is made with analytical results in the literature to verify the model created and the results obtained. It was found that the results obtained from analytical formulation were in perfect agreements with the FEM study. The numerical results for the stress-intensity factor (SIF) are obtained for various dimensionless quantities related to the geometric and material parameters. Consequently, the effects of these parameters on the stress-intensity factor are discussed. If the FEM analysis is used correctly, it can be an efficient alternative method to the analytical solutions that need time.

• Steel and Composite Structures
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• 제3권3호
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• pp.213-229
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• 2003

A high precision shear deformable triangular element has been proposed for free vibration analysis of composite trapezoidal plates. The element has twelve nodes at the three sides and four nodes inside the element. Initially the element has fifty-five degrees of freedom, which has been reduced to forty-eight by eliminating the degrees of freedom of the internal nodes through static condensation. Plates having different side ratios (b/a), boundary conditions, thickness ratios (h/a=0.01, 0.1 and 0.2), number of layers and fibre angle orientations have been analyzed by the proposed shear locking free element. Trapezoidal laminate with concentrated mass at the centre has also been analyzed. An efficient mass lumping scheme has been recommended, where the effect of rotary inertia has been included. For validation of the present element and formulation few results of isotropic trapezoidal plate and square composite laminate have been compared with those obtained from open literatures. The numerical results for composite trapezoidal laminate have been given as new results.

• 한국공간구조학회논문집
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• 제8권4호
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• pp.81-90
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• 2008

이 논문에서는 적분형 르장드르 다항식을 사용한 3차원 계층적 고체요소의 유한요소 정식화를 보여준다. 제안하는 육면체 고체요소는 절점, 변, 면, 그리고 내부모우드를 포함한은 4개의 서로 다른 모우드로 구성되어 있다. 영에너지 모우드와 일정변형률 조건을 확인하기 위해 고유치 시험과 조각시험이 수행되었다. 여기에 추가되어, 적응적 p-유한요소해석을 위해 유한요소해석으로부터 구한 후처리 응력값의 평활화에 기초를 둔 사후오차평가 기법이 연구된다. 자유도가 증가함에 따라 수렴속도측면에서 균등 p-분배와 불균등 p-분배에 의한 유한요소해의 차이점이 비교된다. 제안된 요소의 성능을 보이기 위해 간단한 캔틸레버보가 테스트되었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.34.1-34.1
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• 2005

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1990년도 봄 학술발표회 논문집
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• pp.53-58
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• 1990

This study was intended to provide efficient algorithms for high quality postprocess on the basis of microcomputers with limited capacity and functionality. Improved methods of postprocessing including stress contouring, internal force diagraming, and displacement animation, were proposed and implemented into a new finite element system. Visualization of three-dimensional structural behaviors was treated with special emphasis.

• Structural Engineering and Mechanics
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• 제18권1호
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• pp.79-90
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• 2004

A high precision shear deformable triangular element has been proposed for bending analysis of triangular plate. The element has twelve nodes at the three sides and four nodes inside the element. Initially the element has thirty-five degrees of freedom, which has been reduced to thirty by eliminating the degrees of freedom of the internal nodes through static condensation. Plates having different boundary conditions, side ratios (b/a) and thickness ratios (h/a = 0.001, 0.1 and 0.2) have been analyzed using the proposed shear locking free element. Concentrated and uniformly distributed transverse loads have been used for the analysis. The formulation is made based on first order shear deformation theory. For validation of the present element and formulation few results of thin triangular plate have been compared with the analytical solutions. Results for thick plate have been presented as new results.

• 대한치과보철학회지
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• 제41권4호
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• pp.393-404
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• 2003

Statement of problem. Higher incidence of prosthetic complications such as screw loosening, screw fracture has been reported for posterior single tooth implant. So, there is ongoing research regarding stability of implant-abutment interface. One of those research is increasing the implant diameter and prosthetic table width to improve joint stability. In another part of this research, internal conical type implant-abutment interface was developed and reported joint strength is higher than traditional external hex interface. Purpose. The purpose of this study is to compare stress distribution in single molar implant between external hex butt joint implant and internal conical joint implant when increasing the implant diameter and prosthetic table width : 4mm diameter, 5mm diameter, 5mm diameter/6mm prosthetic table width. Material and method. Non-linear finite element models were created and the 3-dimensional finite element analysis was performed to see the distribution of stress when 300N static loading was applied to model at $0^{\circ},\;15^{\circ},\;30^{\circ}$ off-axis angle. Results. The following results were obtained : 1. Internal conical joint showed lower tensile stress value than that of external hex butt joint. 2. When off-axis loading was applied, internal conical joint showed more effective stress distribution than external hex butt joint. 3. External hex butt joint showed lower tensile stress value when the implant diameter was increased. 4. Internal conical joint showed lower tensile stress value than external hex butt joint when the implant diameter was increased. 5. Both of these joint mechanism showed lower tensile stress value when the prosthetic table width was increased. Conclusion. Internal conical joint showed more effective stress distribution than external hex joint. Increasing implant diameter showed more effective stress distribution than increasing prosthetic table width.