• 대한기계학회논문집A
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• 제28권4호
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• pp.419-426
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• 2004

In this paper, studied about the effect of open crack and the moving mass on the dynamic behavior of simply supported pipe conveying fluid. The equation of motion is derived by using Lagrange's equation. The influences of the velocity of moving mass, the velocity of fluid flow and a crack have been studied on the dynamic behavior of a simply supported pipe system by numerical method. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. Therefore, the crack is modelled as a rotational spring. Totally, as the velocity of fluid flow is increased, the mid-span deflection of simply supported pipe conveying fluid is increased. The position of the crack is located in the middle point of the pipe, the mid-span deflection of simply supported pipe presents maximum deflection.

• Structural Engineering and Mechanics
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• 제72권1호
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• pp.71-81
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• 2019

The objective of this paper is to develop a size-dependent nonlinear model of beams for fluid-conveying nanotubes with an initial deflection. The nonlinear frequency response of the nanotube is analysed via an Euler-Bernoulli model. Size influences on the behaviour of the nanosystem are described utilising the nonlocal strain gradient theory (NSGT). Relative motions at the inner wall of the nanotube is taken into consideration via Beskok-Karniadakis model. Formulating kinetic and elastic energies and then employing Hamilton's approach, the nonlinear motion equations are derived. Furthermore, Galerkin's approach is employed for discretisation, and then a continuation scheme is developed for obtaining numerical results. It is observed that an initial deflection significantly alters the frequency response of NSGT nanotubes conveying fluid. For small initial deflections, a hardening nonlinearity is found whereas a softening-hardening nonlinearity is observed for large initial deflections.

• Structural Engineering and Mechanics
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• 제20권4호
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• pp.405-420
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• 2005

In this paper, a hybrid/mixed nonlinear shell element is developed in polar coordinate system based on Hellinger/Reissner variational principle and the large-deflection theory of plate. A numerical solution scheme is formulated using the hybrid/mixed finite element method (HMFEM), in which the nodal values of bending moments and the deflection are the unknown discrete parameters. Stability of the present element is studied. The large-deflection analyses are performed for simple supported and clamped circular plates under uniformly distributed and concentrated loads using HMFEM and the traditional displacement finite element method. A parametric study is also conducted in the research. The accuracy of the shell element is investigated using numerical computations. Comparisons of numerical solutions are made with theoretical results, finite element analysis and the available numerical results. Excellent agreements are shown.

• Advances in concrete construction
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• 제7권1호
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• pp.51-63
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• 2019

The project focuses on the dynamic analysis of concrete beams reinforced with silica-nanoparticles under blast loading. The structure is located at two boundary conditions. The equivalent composite properties are determined using Mori-Tanak model. The structure is simulated with sinusoidal shear deformation theory. Employing nonlinear strains-displacements, stress-strain, the energy equations of beam were obtained and using Hamilton's principal, the governing equations were derived. Using differential quadrature methods (DQM) and Newmark method, the dynamic deflection of the structure is obtained. The influences of volume percent and agglomeration of silica nanoparticles, geometrical parameters of beam, boundary condition and blast load on the dynamic deflection were investigated. Results showed that with increasing volume percent of silica nanoparticles, the dynamic deflection decreases.

• Steel and Composite Structures
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• 제46권2호
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• pp.195-202
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• 2023

Dynamic deflection analysis of sandwich beams with cellular core under thermal and pulse loads has been performed in the present article. The cellular core sandwich beam has two layers fortified by graphene oxide powder (GOP) which are micromechanically modeled by Halpin-Tsai formulation. The pulse load has blast type and is applied on the top side of sandwich beam. The system of equations has been developed based on higher-order beam theory and Ritz method. Then, they are solved in Laplace domain to derive the dynamic deflections. The dependency of beam deflection on temperature variation, GOP content, pulse load duration/location and core relative density has been studied in detail.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.114-117
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• 2001

A higher order zig-zag plate theory is developed to refine accurately predict fully coupled of the mechanical, thermal, and electric behaviors. Both the displacement and temperature fields through the thickness are constructed by superimposing linear zig-zag field to the smooth globally cubic varying field. Smooth parabolic distribution through the thickness is assumed in the transverse deflection in order to consider transverse normal deformation. Linear zig-zag form is adopted in the electric field. The layer-dependent degrees of freedom of displacement and temperature fields are expressed in terms of reference primary degrees of freedom by applying interface continuity conditions as well as bounding surface conditions of transverse shear stresses and transverse heat flux The numerical examples of coupled and uncoupled analysis are demonstrated the accuracy and efficiency of the present theory. The present theory is suitable for the predictions of fully coupled behaviors of thick smart composite plate under mechanical, thermal, and electric loadings.

• 대한기계학회논문집A
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• 제25권4호
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• pp.714-724
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• 2001

In this work, some inaccuracies and limitation of prior indentation theory, which is based on the deformation theory of plasticity and experimental observations, are first investigated. Then effects of major material properties on the configuration of indentation load-deflection curve are examined via incremental plasticity theory based finite element analyses. It is confirmed that subindenter deformation and stress-strain distribution from the deformation theory of plasticity are quite dissimilar to those from incremental theory of plasticity. We finally suggest the optimal data acquisition location, where the strain gradient is the least and the effect of friction is negligible. This data acquisition point increases the strain range by a factor of five.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.177-184
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• 2000

In this work, some inaccuracies and limitation of prior indentation theory, which is based on the deformation theory of plasticity and experimental observations, are first investigated. Then effects of major material properties on the configuration of indentation load-deflection curve are examined via incremental plasticity theory based finite element analyses. It is confirmed that subindenter deformation and stress-strain distribution from the deformation theory of plasticity are quite dissimilar to those from incremental theory of plasticity. We finally suggest the optimal data acquisition location, where the strain gradient is the least and the effect of friction is negligible. This data acquisition point increases the strain range by a factor of five.

• 한국소음진동공학회논문집
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• 제26권5호
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• pp.518-527
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• 2016

이 연구는 패널 플러터 시뮬레이션을 위한 집중 하중의 사용을 연구한다. 이러한 구상은 날개 구조의 아음속 플러터 연구에 대해서는 검증된 바 있으나 초음속 영역에서는 그렇지 못하다. 따라서, 4면 단순 지지 경계 조건의 패널에 공기력과 등가의 집중하중을 가하여 초음속 패널 플러터를 연구한다. 분포된 공기력은 수치 적분 계산을 통해 집중 하중들로 근사된다. 선형 패널 플러터에 대한 공탄성 방정식은 고전적인 small-deflection theory와 piston theory를 이용하여 세워지는 반면, 모방된 패널 플러터에서 플러터 방정식은 분포 공기력에 의한 압력을 집중 하중에 의한 압력으로 대체함으로써 유도된다. 최종적으로 플러터 주파수, 임계 동압, 그리고 그에 상응하는 모드형상이 모방된 패널 플러터에 대해 구해지고, 그 결과를 선형 패널 플러터로부터 얻은 결과와 비교하여 검증하였다. 또한 두 가지 중요한 파라미터인 집중 하중의 개수와 위치는 수치적 예제들과 최적화 과정을 통해 각각 논의되었다. 이 연구에서 얻어진 플러터 결과는 집중하중들을 이용하여 패널 플러터를 재현하는 가능성을 논의하는데 타당한 것으로 생각된다.

• 한국구조물진단유지관리공학회 논문집
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• 제4권3호
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• pp.197-204
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• 2000

Tensile strength (stress) of bar splice is important in the research of mechanical behavior of reinforced concrete structures-beam, column etc.- with bar splice. The purpose of this research is to evaluate the flexural behavior - deflection of beam specimens, strain of main bars - of reinforced concrete beam with Lock Joint Coupler. To make a comparative research, reinforced concrete beam specimens with normal deformed bar and lap splice are tested and analyzed. Test results, Comparing a deflection of three types flexural specimens, a flexural specimen with Lock Joint Coupler is 40% greater than the other flexural specimens. At the center of flexural specimen, the strain of main bar(D29) with lock joint coupler is 50% less, and vice versa, at the point of 14cm far from the center of flexural specimen, the strain of main bar(D29) with lock joint coupler is 9% larger than the strain of main bar(D29) which calculated using the classical flexure theory. A discords, between a deflection behavior of the flexural specimens and a strain of the main bar, are caused by the difference of strain between the lock joint coupler and main bar, near the lock joint coupler. So, additional research is need to verify as stated above discords.