• Structural Engineering and Mechanics
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• 제15권1호
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• pp.71-81
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• 2003

The governing differential equation for buckling of a one-step bar with the effect of shear deformation is established and its exact solution is obtained. Then, the exact solution is used to derive the eigenvalue equation of a multi-step bar. The new exact approach combining the transfer matrix method and the closed form solution of one step bar is presented. The proposed methods is convenient for solving the entire and partial buckling of one-step and multi-step bars with various end conditions, with or without shear deformation effect, subjected to concentrated axial loads. A numerical example is given explaining the proposed procedure and investigating the effect of shear deformation on the critical buckling force of a multi-step bar.

• Advances in aircraft and spacecraft science
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• 제7권2호
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• pp.115-134
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• 2020

This paper proposes a bending analysis for a functionally graded piezoelectric (FGP) plate through utilizing a two-variable shear deformation plate theory under simply-supported edge conditions. The number of unknown functions used in this theory is only four. The electric potential distribution is assumed to be a combination of a cosine function along the cartesian coordinate. Applying the analytical solutions of FGP plate by using Navier's approach and the principle of virtual work, the equilibrium equations are derived. The paper also discusses thoroughly the impact of applied electric voltage, plate's aspect ratio, thickness ratio and inhomogeneity parameter. Results are compared with the analytical solution obtained by classical plate theory, first-order-shear deformation theory, higher-order shear deformation plate theories and quasi-three-dimensional sinusoidal shear deformation plate theory.

• Journal of Hydrospace Technology
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• 제1권1호
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• pp.111-124
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• 1995

An improved analysis model for material nonlinearity induced by elasto-plastic deformation and damage including a large strain response was proposed. The elasto-plastic-damage constitutive model based on the continuum damage mechanics approach was adopted to overcome limitations of the conventional plastic analysis theory. It can manage the anisotropic tonsorial damage evolved during the time-independent plastic deformation process of materials. Updated Lagrangian finite element formulation for elasto-plastic damage coupling problems including large deformation, large rotation and large strain problems was completed to develop a numerical model which can predict all kinds of structural nonlinearities and damage rationally. Finally a finite element analysis code for two-dimensional plane problems was developed and the applicability and validity of the numerical model was investigated through some numerical examples. Calculations showed reasonable results in both geometrical nonlinear problems due to large deformation and material nonlinearity including the damage effect.

• 한국의상디자인학회지
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• 제22권3호
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• pp.63-74
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• 2020

Modern clothes are part of formative arts and express experimentation and originality. This tendency is especially prominent in structural fashion. This study set out to analyze structural fashion in various aspects, examining and analyzing the expressive and formative characteristics of Deformation and contribute to the development of creative fashion design. The approach of peer debriefing was used with three fashion experts to identify structural clothes in the women's haute couture collections from a total of 24 seasons from S/S of 2008 to F/W of 2019. The clothes with Deformation characteristics were then identified to analyze expressive and formative characteristics. The expressive characteristics of Deformation in structural clothes were exaggeration, distortion, and recombination. Exaggeration was expressed with exaggerated sizes, forms, and excessive use. Distortion was expressed with distorted forms and functions and through optical illusions. Recombination was expressed with the recombination of forms and roles. The formative characteristics of Deformation were maximum, playfulness, and unfamiliarity. The study connected the expressive characteristics to the formative ones and examined them simultaneously, finding that "distortion" and "playfulness" represented the expressive and formative characteristics, respectively. The characteristics of Deformation are expressed in various ways in structural fashion. If they are considered, they will make valuable contributions to creative ideas.

• 한국컴퓨터그래픽스학회논문지
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• 제18권4호
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• pp.35-40
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• 2012

컴퓨터 그래픽스 분야에서 변형 및 파괴 시뮬레이션은 매우 중요한 기법으로 영화 및 게임 등에서 그 응용 범위가 매우 넓다. 본 논문에서는 방향성 입자를 이용한 고체 시뮬레이션 기법[1]을 확장하여 과도한 변형에 의한 파괴 현상을 실시간에 안정적으로 근사할 수 있는 실용적인 기법을 제안한다. 제안된 기법은 방향성 입자 집합의 최적 회전을 엄밀히 계산함으로써 순수 신축을 정확히 얻을 수 있으며 이를 이용하여 파괴 현상을 손쉽게 정형화할 수 있다. 본 논문의 실험에서는 대규모 모델의 변형 및 파괴 시뮬레이션도 실시간에 수행되었다.

• Structural Engineering and Mechanics
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• 제14권4호
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• pp.455-472
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• 2002

The paper involves the study on the elastic and elasto-plastic stress wave propagation in the 1-D and 2-D solid media. The Smooth Particle Hydrodynamics equations governing the elastic and elasto-plastic large deformation dynamic response of solid structures are presented. The proposed additional stress points are introduced in the formulation to mitigate the tensile instability inherent in the SPH approach. Both incremental rate approach and leap-frog algorithm for time integration are introduced and the new solution algorithm is developed and implemented. Two examples on stress wave propagation in aluminium bar and 2-D elasto-plastic steel plate are included. Results from the proposed SPH approach are compared with available analytical values and finite element solutions. The comparison illustrates that the stress wave propagation problems can be effectively solved by the proposed SPH method. The study shows that the SPH simulation is a reliable and robust tool and can be used with confidence to treat transient dynamics such as linear and non-linear transient stress wave propagation problems.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권6호
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• pp.730-740
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• 2018

Hydrofoil is the direct component to generate thrust for underwater glider. It is significant to improve propulsion efficiency of hydrofoil. This study optimizes the shape of a hydrofoil using Free-Form Deformation (FFD) parametric approach and Surrogate-based Optimization (SBO) algorithm. FFD approach performs a volume outside the hydrofoil and the position changes of control points in the volume parameterize hydrofoil's geometric shape. SBO with adaptive parallel sampling method is regarded as a promising approach for CFD-based optimization. Combination of existing sampling methods is being widely used recently. This paper chooses several well-known methods for combination. Investigations are implemented to figure out how many and which methods should be included and the best combination strategy is provided. As the hydrofoil can be stretched from airfoil, the optimizations are carried out on a 2D airfoil and a 3D hydrofoil, respectively. The lift-drag ratios are compared among optimized and original hydrofoils. Results show that both lift-drag-ratios of optimized hydrofoils improve more than 90%. Besides, this paper preliminarily explores the optimization of hydrofoil with root-tip-ratio. Results show that optimizing 3D hydrofoil directly achieves slightly better results than 2D airfoil.

• 한국지반공학회논문집
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• 제23권12호
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• pp.117-124
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• 2007

지진으로 인해 사면에 발생한 영구적 변형 계산시 고려된 공간평균과 유연도의 영향을 조사하였다. 현재 변위계산에는 Newmark이 제안한 강체블럭해석기법이 이 기법의 효율적인 계산능력으로 인해 광범하게 사용되고 있다. 그러나 이 해석기법은 지진응답해석과 변위해석을 별도로 수행하는 소위 분리해석법을 채택하고 있다. 당초의 Newmark 해석기법은 활동토사를 강성체로 가정했으며 이로 인하여 비보수적 결과가 도출될 수 있다는 비판을 받아왔다. 본 논문은 Newmark-형식의 해석에서 강성체 가정의 영향을 검토하였다. 활동토사에 작용하는 지진하중의 전체 효과를 공간평균기법을 사용하여 평가하였으며 그 결과를 주파수 영역에서 분석하였다. 해석결과로부터 활동토사의 유연도 수준을 결정하는 경우 사용할 수 있는 단순한 지표를 제시하였다.

• 대한기계학회논문집A
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• 제28권6호
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• pp.685-692
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• 2004

A stochastic approach has been presented for superplastic deformation of Ti-6Al-4V alloy, and probability functions are used to model the heterogeneous phase distributions. The experimentally observed spatial correlation functions are developed, and microstructural evolutions together with superplastic deformation behavior have been investigated by means of the two-point and three-point probability functions. The results have shown that the probability varies approximately linearly with separation distance, and deformation enhanced probability changes during the process. The stress-strain behavior with the evolutions of probability function can be correctly predicted by the model. The finite element implementation using Monte Carlo simulation associated with reconstructed microstructures shows that better agreement with experimental data of failure strain on the test specimen.

• Smart Structures and Systems
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• 제21권1호
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• pp.113-122
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• 2018

In this article, an exact analytical solution for mechanical buckling analysis of magnetoelectroelastic plate resting on pasternak foundation is investigated based on the third-order shear deformation plate theory. The in-plane electric and magnetic fields can be ignored for plates. According to Maxwell equation and magnetoelectric boundary condition, the variation of electric and magnetic potentials along the thickness direction of the plate is determined. The von Karman model is exploited to capture the effect of nonlinearity. Navier's approach has been used to solve the governing equations for all edges simply supported boundary conditions. Numerical results reveal the effects of (i) lateral load, (ii) electric load, (iii) magnetic load and (iv) higher order shear deformation theory on the critical buckling load have been investigated. These results must be the analysis of intelligent structures constructed from magnetoelectroelastic materials.