• Structural Engineering and Mechanics
• /
• v.51 no.2
• /
• pp.333-347
• /
• 2014

Nonlinear bending of super-elliptical plates of uniform thickness under uniform transverse pressure was investigated by the Ritz method. The material was assumed to be homogeneous and isotropic. The contribution of the boundary conditions at the point supports was introduced by the Lagrange multipliers. The solution was obtained by the Newton-Raphson method. The influence of the location of the point supports on the central deflection was highlighted by sensitivity analysis. An approximate relationship between the central deflection and the super-elliptical power was obtained using the method of least squares. The critical points where the maximum deflection may develop, and the influence of nonlinearity were highlighted. The nonlinearity was found to be sensitive to the aspect ratio. The accuracy of the algorithm was validated by comparing the central deflection with the solutions of elliptical and rectangular plates.

• Journal of Industrial Technology
• /
• v.16
• /
• pp.131-137
• /
• 1996

For a large scale civil and architectural structures, mainly steel, concrete and aluminum have been used and weight and corrosion of materials became a major concern. Designing with composite materials is very much complicated. Simple classical theory may yield good results for selecting "initial" sections for preliminary design. D. H. Kim proposed to use the quasi-isotropic constants by Tsai for the preliminary design of the composite primary structures for the civil construction. Also he made simple equation using correction factor. In this paper, the simple formulas developed by D. H. Kim to obtain "exact" values of the natural frequencies of [ABBCAAB]r laminate are compared with Whitney's equations. Also natural frequencies of the plate with varying aspect ratios and reinforcing fiber orientations, are compared with natural frequencies of bean. This work can be a guideline to obtain data in many other cases.

• Journal of KSNVE
• /
• v.8 no.4
• /
• pp.623-631
• /
• 1998

The free vibration analyses of the isotropic and composite(CFRP, GFRP) rectangular plates with point supports at the free edge and middle position are performed. The natural frequencies and nodal patterns of plates with point supports are experimentally determined by impact testing using an impact hammer. To compare and verify these experimental results, the finite element analysis is also carried out. The effect of the point support position, the number of point supports, and the anisotropic parameters on the natural frequencies and nodal patterns of cantilevered rectangular plates are investigated.

• Journal of Ocean Engineering and Technology
• /
• v.34 no.2
• /
• pp.97-109
• /
• 2020

In this study, ultimate strength characteristics of clamped sandwich panels with metal faces and an elastic isotropic core under combined in-plane compression and lateral pressure loads are investigated to verify the applicability of the ultimate strength design formula for ship structures. Alternative elastomer-cored steel sandwich panels are selected instead of the conventional bottom stiffened panels for a Suezmax-class tanker and then the ultimate strength characteristics of the selected sandwich panels are examined by using nonlinear finite element analysis. The change in the ultimate strength characteristics due to the change in the thickness of the face plate and core as well as the amplitude of lateral pressure are summarized and compared with the results obtained by using the ultimate strength design formula and nonlinear finite element analysis. The insights and conclusions developed in the present study will be useful for the design and development of applications for sandwich panels in double hull tanker structures.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2013.04a
• /
• pp.353-358
• /
• 2013

Present paper deals with turbulence-airfoil interaction noise and mainly investigates the effects of airfoil thickness on the broadband noise spectrum. The acoustic power radiation from an airfoil is predicted using high-order time-domain method, which is based on the computational aeroacoustic technique solving the linear Euler equations. The homogeneous and isotropic turbulence is generated by utilizing the synthetic turbulence modeling based on random particle method. The airfoils taken into consideration are a flat-plate and a NACA0012 airfoil aligned with uniform mean flow. The effects of airfoil thickness on the radiated inflow turbulence noise are investigated by comparing acoustic power spectrum predicted for each airfoil. The comparison of acoustic power spectrum reveals that the airfoil thickness significantly contributes the high frequency noise reduction.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2011.04a
• /
• pp.760-763
• /
• 2011

본 논문의 목적은 효율적인 3절점 판 유한요소를 개발하는 것이다. Hellinger-Reissner 범함수에 근거한 혼합정식화(mixed formulation)를 사용한다. 잠김현상을 일으키는 전단변형률장을 독립적으로 분리한 후, MITC(Mixed Interpolation of Tensorial Components)방법을 이용하여 대체전단변형률장(assumed transverse shear strain field)을 구성한다. 추가적으로 회전된 반변기저벡터(contravariant base vector)로 정의된 근사전단변형률장(approximated transverse shear strain field)에 미지수(unknowns)를 도입하여 혼합정식화를 완성시키고 정적응축(static condensation)을 통해 최종 강성행렬을 구성한다. 거짓영에너지모드시험(spurious zero energy mode test), 조각시험(patch test), 등방성시험(isotropic test) 등을 실시하였으며, 4변 완전구속 정사각형 판 구조물과 60도 기울어진 단순지지 판 구조물 등 예제들을 해석하여 MITC3판 유한요소와 수렴성능을 비교하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2007.04a
• /
• pp.399-402
• /
• 2007

The classical two dimensional modulus of rupture test was generalized to three dimensions. Using this new method, the biaxial tensile strength can be measured with only one actuator. A circular plate is used in this method unlike a prismatic beam in the classical modulus of rupture test. The stress field in this specimen is isotropic and uniform in a plane paralle1 to the bottom surface of the specimen. The relation between the applied load and the maximum stress is derived analytical1y using Timoshenko's solution. A set of experimental data is presented.

• Structural Engineering and Mechanics
• /
• v.57 no.2
• /
• pp.315-325
• /
• 2016

A new first-order shear deformation theory is developed for dynamic behavior of functionally graded beams. The equations governing the axial and transverse deformations of functionally graded plates are derived based on the present first-order shear deformation plate theory. The governing equations and boundary conditions of functionally graded beams have the simple forms as those of isotropic plates. The influences of the volume fraction index and thickness-to-length ratio on the fundamental frequencies are discussed. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions.

• Structural Engineering and Mechanics
• /
• v.11 no.4
• /
• pp.461-468
• /
• 2001

The aim of this work is to establish the coefficient that defines the critical buckling load for isotropic annular plates of variable thickness whose outer boundary is simply supported and subjected to uniform pressure. It is assumed that the plate thickness varies in a continuous way, according to an exponential law. The eigenvalues are determined using an optimized Rayleigh-Ritz method with polynomial coordinate functions which identically satisfy the boundary conditions at the outer edge. Good engineering agreement is shown to exist between the obtained results and buckling parameters presented in the technical literature.

• Structural Engineering and Mechanics
• /
• v.15 no.2
• /
• pp.199-223
• /
• 2003

The formulation of a non-linear shear deformable shell element is presented for the solution of stability problems of stiffened plates and shells. The formulation of the geometrical stiffness presented here is exactly defined on the midsurface and is efficient for analyzing stability problems of thick plates and shells by incorporating bending moment and transverse shear resultant force. As a result of the explicit integration of the tangent stiffness matrix, this formulation is computationally very efficient in incremental nonlinear analysis. The element is free of both membrane and shear locking behaviour by using the assumed strain method such that the element performs very well in the thin shells. By using six degrees of freedom per node, the present element can model stiffened plate and shell structures. The formulation includes large displacement effects and elasto-plastic material behaviour. The material is assumed to be isotropic and elasto-plastic obeying Von Mises's yield condition and its associated flow rules. The results showed good agreement with references and computational efficiency.