• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2492-2502
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• 2002

A rubber-like material model is generally characterized by hyperelasticity and formulated by a total stress-total strain relationship because the material shows nonlinear elastic behaviour under large deformation. In this study, a pressure potential obtained by a separately interpolated pressure is introduced to the non-linear finite element formulation incorporating with incompressible or almost incompressible condition of the material. The present formulation is somewhat different from the general formulation using the pressure computed in the displacement field. A non-linear finite element analysis program is developed for the plane strain and the axisymmetric contact problems of a rubber-like material. Various examples with rubber material are analyzed for its verification. The results about deformed shapes and stress distributions thought to be meaningful in comparison with a commercial program, MARC.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.10
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• pp.836-843
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• 2008

An efficient domain/boundary decomposition method is applied for heat transfer problems with non-linear thermal radiation boundaries. The whole domain of solids or structures is considered as set of subdomains, an interface, and radiation interfaces. In a variational formulation, simple penalty functions are introduced to connect an interface or radiation interfaces with neighboring subdomains that satisfy continuity conditions. As a result, non-linear finite element computations due to the thermal radiation boundaries can be localized within a few subdomains or radiation interfaces. Therefore, by setting up suitable solution algorithms for the governing finite element equations, the computational efficiency can be improved considerably. Through a set of numerical examples, these distinguishing characteristics of the present method are investigated in detail.

• Steel and Composite Structures
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• v.4 no.6
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• pp.489-507
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• 2004

The flexibility of the connection between steel and concrete largely influences the global behaviour of the composite beam. Therefore the way the connection is modelled is the key issue in its structural analysis. Here we present a new strain-based finite element formulation in which we consider non-linear material and contact models. The computational efficiency and accuracy of the formulation is proved with the comparison of our numerical results with the experimental results of Abdel Aziz (1986) obtained in a full-scale laboratory test. The shear connectors are assumed to follow a non-linear load-slip relationship proposed by Ollgaard et al. (1971). We introduce the notion of the generalized slip, which offers a better physical interpretation of the behaviour of the contact and gives an additional material slip parameter. An excellent agreement of experimental and numerical results is obtained, using only a few finite elements. This demonstrates that the present numerical approach is appropriate for the evaluation of behaviour of planar composite beams and perfect for practical calculations.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.999-1004
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• 2004

A numerical method and algorithms is proposed to perform optimization of non-linear response structures. An analytical and numerical method based finite element method is also proposed for the transformation of non-linear response into linear response. Loads transformed from this method are defined as the equivalent linear loads. With the loads and the transformed response, linear static optimization is performed for nonlinear response structure with geometric and/or material non-linearity. The results of the optimization are compared with them of typical non-linear response optimization using finite difference method. The proposed method is very efficient and derives good solution.

• Structural Engineering and Mechanics
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• v.68 no.3
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• pp.299-312
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• 2018

In this paper, an extended finite element method is proposed to analyze both geometric and material non-linear behavior of general Functionally Graded Material (FGM) plate-shell type structures. A user defined subroutine (UMAT) is developed and implemented in Abaqus/Standard to study the elastoplastic behavior of the ceramic particle-reinforced metal-matrix FGM plates-shells. The standard quadrilateral 4-nodes shell element with three rotational and three translational degrees of freedom per node, S4, is extended in the present study, to deal with elasto-plastic analysis of geometrically non-linear FGM plate-shell structures. The elastoplastic material properties are assumed to vary smoothly through the thickness of the plate-shell type structures. The nonlinear approach is based on Mori-Tanaka model to underline micromechanics and locally determine the effective FGM properties and self-consistent method of Suquet for the homogenization of the stress-field. The elasto-plastic behavior of the ceramic/metal FGM is assumed to follow Ludwik hardening law. An incremental formulation of the elasto-plastic constitutive relation is developed to predict the tangent operator. In order to to highlight the effectiveness and the accuracy of the present finite element procedure, numerical examples of geometrically non-linear elastoplastic functionally graded plates and shells are presented. The effects of the geometrical parameters and the volume fraction index on nonlinear responses are performed.

• Structural Engineering and Mechanics
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• v.41 no.6
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• pp.775-789
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• 2012

This paper focuses on post-buckling analysis of functionally graded Timoshenko beam subjected to thermal loading by using the total Lagrangian Timoshenko beam element approximation. Material properties of the beam change in the thickness direction according to a power-law function. The beam is clamped at both ends. The considered highly non-linear problem is solved by using incremental displacement-based finite element method in conjunction with Newton-Raphson iteration method. As far as the authors know, there is no study on the post-buckling analysis of functionally graded Timoshenko beams under thermal loading considering full geometric non-linearity investigated by using finite element method. The convergence studies are made and the obtained results are compared with the published results. In the study, with the effects of material gradient property and thermal load, the relationships between deflections, end constraint forces, thermal buckling configuration and stress distributions through the thickness of the beams are illustrated in detail in post-buckling case.

• Journal of KSNVE
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• v.9 no.3
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• pp.472-476
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• 1999

The effect of static preload on the dynamic properties of rubber materials is rather important, especially when good isolation characteristics are required at high frequencies. However, there are still few papers for dynamic characteristics of compressed rubber components. It was demonstrated in reference (4) that for bonded rubber material of a cylindrical shape, a simplified theory equation between linear dynamic and nonlinear static behavior of rubber material was useful to predict their combined effects. This paper presents the second part of the study. It is confirmed that for the compressed rubber material, the stress can be factored into a function of frequency and a function of strain(stretch). The finite element methodis applied to analyze non-linear large deformation of rubber material and its results are compared with those of a simplified theory equation. The predicted dynamic material properties based on non-linear static finite element analyses have a good agreement of experimental results and those based on simplified theory equation.

• Journal of Mechanical Science and Technology
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• v.14 no.6
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• pp.666-674
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• 2000

Large deflection dynamic responses of laminated composite cylindrical shells under impact are analyzed by the geometrically nonlinear finite element method based on a generalized Sander's shell theory with the first order transverse shear deformation and the von-Karman large deflection assumption. A modified indentation law with inelastic indentation is employed for the contact force. The nonlinear finite element equations of motion of shell and an impactor along with the contact laws are solved numerically using Newmark's time marching integration scheme in conjunction with Akay type successive iteration in each step. The ply failure region of the laminated shell is estimated using the Tsai- Wu quadratic interaction criteria. Numerical results, including the contact force histories, deflections and strains are presented and compared with the ones by linear analysis. The effect of the radius of curvature on the composite shell behaviors is investigated and discussed.

• Earthquakes and Structures
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• v.10 no.2
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• pp.483-494
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• 2016

Historical structures that function as a bridge from past to present are the cultural and social reflections of societies. Masonry bridges are one of the important historical structures. These bridges are vulnerable against to seismic action. In this study, linear and non-linear dynamic analyses of historical Nadir Bridge are assessed. The bridge is modelled with three dimensional finite elements. For the seismic effect, artificial acceleration records are generated considering the seismic characteristics of the region where the bridge is located. Seismic response of the bridge is investigated.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.286-291
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• 2000

The finite element analyses of mechanical rubber components are executed to predict the behavior of deformation and stress distribution in destgn step. The non-linear properties of rubber which are described as strain energy functions are important parameters to design and evaluate rubber components. These are determined by material tests which are tension, compression and shear test. The behaviors of loads-displacements of rubber components such as a roll tubber spring and resilient ring and additional spring for railway suspension system are evaluated by using commercial FEA code. It is shown that the results by FEA simulations are in close agreement with the test results.