• 한국소음진동공학회논문집
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• 제23권6호
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• pp.574-580
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• 2013

At high frequencies, the statistical approach such as statistical energy analysis(SEA) and energy flow analysis(EFA) has been applied for estimation of vibroacoustic responses of various built-up structures. The energy coupling relationship between finite coupled structures is required to estimate vibrational energetics of built-up structures. Mindlin plate theory includes the rotatory inertia and shear deformation effects which are dominant as frequency increases. In this paper, the wave transmission analysis is successfully performed for EFA of co-planar coupled Mindlin plates.

• 한국소음진동공학회논문집
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• 제13권12호
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• pp.947-955
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• 2003

This research analyzes the dynamic stability of stiffened plates on elastic foundations using the finite element method. For analyzing the stiffened plates, both the Mindlin plate theory and Timoshenko beam-column theory were applied. In application of the finite element method, 8-nodes serendipity element system and 3-nodes finite element system were used for plate and beam elements, respectively Elastic foundations were modeled as the Pasternak foundations in which the continuity effect of foundation is considered. In order to verify the theory of this study, solutions obtained by this analysis were compared with the classical solutions in open literature and experimental solutions. The dynamic stability legions of stiffened plates on Pasternak foundations were determined according to changes of in-plane stresses, foundation parameters and dimensions of stiffener.

• Structural Engineering and Mechanics
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• 제83권5호
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• pp.617-625
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• 2022

A novel three variable refined plate theory (TVRPT) is developed in this article for laminated composite plates for the first time. The theory takes into account the nonlinear variation of transverse shear deformations, and satisfies the boundary conditions of zero traction on the plate surfaces without considering the "shear correction factor". The important characteristic of this new kinematic is that the unknowns numbers is only 3 as is employed in "classical plate theory" (CPT). The numerical results of the current theory are compared with 3D-elasticity solutions and the calculations of "first order theories" and other higher order models found in the literature.

• Structural Engineering and Mechanics
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• 제51권5호
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• pp.867-891
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• 2014

An equivalent single layer trigonometric shear deformation theory taking into account transverse shear deformation effect as well as transverse normal strain effect is presented for static flexure of cross-ply laminated composite and sandwich plates. The inplane displacement field uses sinusoidal function in terms of thickness coordinate to include the transverse shear deformation effect. The cosine function in thickness coordinate is used in transverse displacement to include the effect of transverse normal strain. The kinematics of the present theory is much richer than those of the other higher order shear deformation theories, because if the trigonometric term (involving thickness coordinate z) is expanded in power series, the kinematics of higher order theories (which are usually obtained by power series in thickness coordinate z) are implicitly taken into account to good deal of extent. Governing equations and boundary conditions of the theory are obtained using the principle of virtual work. The closed-form solutions of simply supported cross-ply laminated composite and sandwich plates have been obtained. The results of present theory are compared with those of the classical plate theory (CPT), first order shear deformation theory (FSDT), higher order shear deformation theory (HSDT) of Reddy and exact three dimensional elasticity theory wherever applicable. The results predicted by present theory are in good agreement with those of higher order shear deformation theory and the elasticity theory.

• Structural Engineering and Mechanics
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• 제66권5호
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• pp.665-676
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• 2018

In this study, a four-node quadrilateral partial mixed plate element with low degrees of freedom (dofs) is developed for static and free vibration analysis of functionally graded material (FGM) plates rested on Winkler-Pasternak elastic foundations. The formulation of the presented finite element model is based on a parametrized mixed variational principle which is developed recently by the first author. The presented finite element model considers the effects of shear deformations and normal flexibility of the FGM plates without using any shear correction factor. It also fulfills the boundary conditions of the transverse shear and normal stresses on the top and bottom surfaces of the plate. Beside these capabilities, the number of unknown field variables of the plate is only six. The presented partial mixed finite element model has been validated through comparison with the results of the three-dimensional (3D) theory of elasticity and the results obtained from the classical and high-order plate theories available in the open literature.

• Structural Engineering and Mechanics
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• 제30권4호
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• pp.501-512
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• 2008

The axisymmetric problem of a functionally graded annular plate is considered by extending the theory of functionally graded materials plates suggested by Mian and Spencer (1998). In particular, their expansion formula for displacements is adopted and the hypothesis that the material parameters can vary along the thickness direction in an arbitrary continuous fashion is retained. However, their analysis is extended here in two aspects. First, the material is assumed to be transversely isotropic, rather than isotropic. Second, the plate is no longer tractions-free on the top and bottom surfaces, but subject to uniform loads applied on the surfaces. The elasticity solutions are given for a uniformly loaded annular plate of functionally graded materials for a total of six different boundary conditions. Numerical results are given for a simply supported functionally graded annular plate, and good agreement with those by the classical plate theory is obtained.

• 한국전산구조공학회논문집
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• 제24권3호
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• pp.249-257
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• 2011

본 논문에서는 고전적 고차전단변형이론(HSDT)을 이용한 복합재료 적층평판의 응력해석 개선기법을 소개한다. 횡방향 응력들에 대해서만 변분을 취하는 혼합변분이론(Mixed variational theorem)을 통하여 횡방향 전단 변형에너지를 개선하였다. 가정된 횡방향 전단응력은 면내 변위가 5차 다항식을 갖는 고차 지그재그 이론으로부터 구하였으며, 변위들은 고전적 고차전단변형이론의 변위장을 사용하였다. 이 과정을 통하여 얻어진 변형 에너지를 본 논문에서는 EHSDTM라고 명명하였으며, 이 이론을 통해 복합재 적층평판의 변위와 응력을 계산함에 있어서 HSDT와 비슷한 수준의 계산적 효율을 가지면서, 동시에 최소자승오차법에 따른 후처리 과정을 적용함으로써 변위와 응력의 두께방향 분포를 정확하게 예측할 수 있도록 개선하였다. 계산된 결과는 고전적 HSDT, 3차원 탄성해 등의 여러 결과들과 비교하여 검증하였다.

• 한국공간구조학회논문집
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• 제5권3호
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• pp.65-74
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• 2005

본 연구에서는 사각형 모듈의 인발성형된 복합재료 바닥판의 휨 거동에 대한 해석 모델을 개발하였다. FRP 바닥판의 해석 모델은 FSDT 평판 이론을 기반으로 임의 적층각을 지닌 FRP 바닥판의 처짐을 예측할 수 있었다. 수치적 예제에서는 네 변이 단순 지지된 등분포 하중을 받는 사각형 모듈의 FRP 바닥판을 2차원 평판 유한 요소해석을 적용하여 수행하였고, 해석 결과에 대해서는 바닥판 길이-높이의 비와 화이버 각도의 변화에 따른 효과에 대해 역점을 두고 다루었다. 연구 결과, 본 연구에서 제안한 해석 모델이 FRP 바닥판의 휨 거동을 해석하고 예측하는데 효과적이고 정확하다는 것이 입증되었다. 또한, FRP 바닥판의 높이가 높아질수록 plate 해석 이론에 있어서 일차전단변형이론(First order Shear Deformable laminated plate Theory : FSDT)이 아닌 고차전단변형(Higher order Shear Deformable plate Theory : HSDT)의 필요성에 대해 언급하였다.

• Composites Research
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• 제32권1호
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• pp.13-20
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• 2019

본 연구에서는 전기 자동차의 주요 부품 중 하나인, Battery Module의 품질 Issue 및 부품특성 개선을 위해 복합재료를 사용하여 구조보강 하였으며, 단일소재의 단점을 극복할 수 있는 Hybrid 개념의 기구 구조 최적화를 수행하고 성능을 비교하였다. 이를 위해 고전 적층 판 이론(Classical Laminated Plate Theory, CLPT)에 따른 복합재료 주요 설계 변수 도출 및 복합재료 물성 예측 알고리즘에 대해 연구하였으며, 설계된 복합재료의 기계적 물성을 바탕으로 유한요소해석(FEM)을 통해 Battery Module의 성능을 검증하였다. 이를 통해 자동차 Battery 부품의 안정성 및 경량화 등의 부품 특성 개선 여부를 확인할 수 있었다. 최종적으로 검증결과에 따르면 Selective Composite Patch로 보강된 Hybrid Battery Module은 기존 Al Battery Module에 비해 30%의 중량 감소 및 제품 두께 32.5%를 줄일 수 있고, 충격 성능 유지 등 Hybrid 구조의 장점을 입증하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1997년도 가을 학술발표회 논문집
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• pp.73-79
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• 1997

It is one of classical problems in the elastic theory to analyze contact stresses between elastic bodies. Concrete pavements under traffic wheel loads can be considered as one of these typical Problems. In the paper, Mindlin plate theory is used to consider the transverse shear effect, 8-node isoparametric plate bending element is adopted in this study, and an elastic plate resting on tensionless elastic half-space is analyzed by finite element method. The Boussineq's solution of elastic half-space is used to evaluate the flexibility of foundation. To obtain the boundary of contact area, the flexibility matrix of foundation is modified after each cycle of analysis iteratively. A Numerical example is presented by using these method.