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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Computational Structural Engineering Institute of Korea
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Journal DOI :
The Computational Structural Engineering Institute
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Volume & Issues
Volume 25, Issue 6 - Dec 2012
Volume 25, Issue 5 - Oct 2012
Volume 25, Issue 4 - Aug 2012
Volume 25, Issue 3 - Jun 2012
Volume 25, Issue 2 - Apr 2012
Volume 25, Issue 1 - Feb 2012
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Development of Finite Element Domain Decomposition Method Using Local and Mixed Lagrange Multipliers
Kwak, Jun Young ; Cho, Hae Seong ; Shin, Sang Joon ; Bauchau, Olivier A. ;
Journal of the Computational Structural Engineering Institute of Korea, volume 25, issue 6, 2012, Pages 469~476
DOI : 10.7734/COSEIK.2012.25.6.469
In this paper, a finite element domain decomposition method using local and mixed Lagrange multipliers for a large scal structural analysis is presented. The proposed algorithms use local and mixed Lagrange multipliers to improve computational efficiency. In the original FETI method, classical Lagrange multiplier technique was used. In the dual-primal FETI method, the interface nodes are used at the corner nodes of each sub-domain. On the other hand, the proposed FETI-local analysis adopts localized Lagrange multipliers and the proposed FETI-mixed analysis uses both global and local Lagrange multipliers. The numerical analysis results by the proposed algorithms are compared with those obtained by dual-primal FETI method.
Optimal Design of Deep-Sea Pressure Hulls using CAE tools
Jeong, Han Koo ; Henry, Panganiban ;
Journal of the Computational Structural Engineering Institute of Korea, volume 25, issue 6, 2012, Pages 477~485
DOI : 10.7734/COSEIK.2012.25.6.477
Geometric configurations such as hull shape, wall thickness, stiffener layout, and type of construction materials are the key factors influencing the structural performance of pressure hulls. Traditional theoretical approach provides quick and acceptable solutions for the design of pressure hulls within specific geometric configuration and material. In this paper, alternative approaches that can be used to obtain optimal geometric shape, wall thickness, construction material configuration and stiffener layout of a pressure hull are presented. CAE(Computer Aided Engineering) based design optimization tools are utilized in order to obtain the required structural responses and optimal design parameters. Optimal elliptical meridional profile is determined for a cylindrical pressure hull design using metamodel-based optimization technique implemented in a fully-integrated parametric modeler-CAE platform in ANSYS. While the optimal composite laminate layup and the design of ring stiffener for a thin-walled pressure hull are obtained using gradient-based optimization method in OptiStruct. It is noted that the proposed alternative approaches are potentially effective for pressure hull design.
Study on Bullet-Proof Performance of Multi-Layered Hybrid Armor Against 9mm FMJ Projectile
Lee, Jong-Gu ; Kim, Siho ; Kim, Gunin ; Cho, Maenghyo ;
Journal of the Computational Structural Engineering Institute of Korea, volume 25, issue 6, 2012, Pages 487~495
DOI : 10.7734/COSEIK.2012.25.6.487
In order to prevent the high velocity bullet from penetration, aluminum alloy and RHA(Rolled Homogeneous Armour) steel, which have a high tensile and compressive strength, are usually used as the bullet-proof armor material. Although these materials have a good bullet proof performance, but not an area density which is a weight increasing factor of bullet-proof armor. Therefore, Mg(magnesium) alloy is a promising substitute for the traditional bullet-proof armor material due to the relatively low areal density. The spatial efficiency of Mg alloy, however, is inferior to the traditional material's, which is a volume(thickness) increasing factor of bullet-proof armor. In this study, we select the multi-layered hybrid armor which consist of Ceramic, with a high strength; Mg alloy, with a low areal density; Kevlar, with a high tensile strength-to-weight ratio; in order to make up for the poor spatial efficiency of Mg alloy. By predicting V50 of the multi-layered armor against 9mm FMJ(Full Metal Jarket). we show that the multi-layered armor have the capability in improving bullet-proof performance in the respect of the areal density, but also the spatial efficiency.
Isogeometric Shape Sensitivity Analysis in Generalized Curvilinear Coordinate Systems
Ha, Youn Doh ; Yoon, Minho ; Cho, Seonho ;
Journal of the Computational Structural Engineering Institute of Korea, volume 25, issue 6, 2012, Pages 497~504
DOI : 10.7734/COSEIK.2012.25.6.497
Finite element analysis is to approximate a geometry model developed in computer-aided design(CAD) to a finite element model, thus the conventional shape design sensitivity analysis and optimization using the finite element method have some difficulties in the parameterization of geometry. However, isogeometric analysis is to build a geometry model and directly use the functions describing the geometry in analysis. Therefore, the geometric properties can be embedded in the NURBS basis functions and control points so that it has potential capability to overcome the aforementioned difficulties. In this study, the isogeometric structural analysis and shape design sensitivity analysis in the generalized curvilinear coordinate(GCC) systems are discussed for the curved geometry. Representing the higher order geometric information, such as normal, tangent and curvature, yields the isogeometric approach to be the best way for generating exact GCC systems from a given CAD geometry. The developed GCC isogeometric structural analysis and shape design sensitivity analysis are verified to show better accuracy and faster convergency by comparing with the results obtained from the conventional isogeometric method.
Efficient Thermal Stress Analysis of Laminated Composite Plates using Enhanced First-order Shear Deformation Theory
Han, Jang-Woo ; Kim, Jun-Sik ; Cho, Maenghyo ;
Journal of the Computational Structural Engineering Institute of Korea, volume 25, issue 6, 2012, Pages 505~512
DOI : 10.7734/COSEIK.2012.25.6.505
In this paper, an efficient yet accurate method for the thermal stress analysis using a first order shear deformation theory(FSDT) is presented. The main objective herein is to systematically modify transverse shear strain energy through the mixed variational theorem(MVT). In the mixed formulation, independent transverse shear stresses are taken from the efficient higher-order zigzag plate theory, and the in-plane displacements are assumed to be those of the FSDT. Moreover, a smooth parabolic distribution through the thickness is assumed in the transverse normal displacement field in order to consider a transverse normal deformation. The resulting strain energy expression is referred to as an enhanced first order shear deformation theory, which is obtained via the mixed variational theorem with transverse normal deformation effect(EFSDTM_TN). The EFSDTM_TN has the same computational advantage as the FSDT_TN(FSDT with transverse normal deformation effect) does, which allows us to improve the through-the-thickness distributions of displacements and stresses via the recovery procedure. The thermal stresses obtained by the present theory are compared with those of the FSDT_TN and three-dimensional elasticity.
Seismic Performance Evaluation of Complex-Shaped Tall Buildings by Lateral Resisting Systems
Youn, Wu-Seok ; Lee, Dong-Hun ; Cho, Chang-Hee ; Kim, Eun-Seong ; Lee, Dong-Chul ; Kim, Jong-Ho ;
Journal of the Computational Structural Engineering Institute of Korea, volume 25, issue 6, 2012, Pages 513~523
DOI : 10.7734/COSEIK.2012.25.6.513
The objective of this research is to examine how the lateral resisting system of selected prototypes are affected by seismic zone effect and shape irregularity on its seismic performance. The lateral resisting systems are divided into the three types, diagrid, braced tube, and outrigger system. The prototype models were assumed to be located in LA, a high-seismicity region, and in Boston, a low-seismicity region. The shape irregularity was classified with rotated angle of plane,
. This study performed two parts of analyses, Linear Response and Non-Linear Response History(NLRH) analysis. The Linear Response analysis was used to check the displacement at the top and natural period of models. NLRH analysis was conducted to invest base shear and story drift ratio of buildings. As results, the displacement of roof and natural period of three structural systems increase as the building stiffness reduces due to the changes in rotation angle of the plane. Also, the base shear is diminished by the same reason. The result of NLRH, the story drift ratio, that was subject to Maximum Considered Earthquake(MCE) satisfied 0.045, a recommended limit according to Tall Building Initiative(TBI).
An Experimental Study on the Structural Behavior of Steel Grid Shear Wall subjected to Axial Force and Cyclic Lateral Load
Park, Jung Woo ; Sim, Ki Chul ; Park, Jin Young ; Lee, Young Hak ; Kim, Heecheul ;
Journal of the Computational Structural Engineering Institute of Korea, volume 25, issue 6, 2012, Pages 525~532
DOI : 10.7734/COSEIK.2012.25.6.525
The recently constructed buildings are ensuring seismic safety with enhanced design criteria. But, the buildings unapplied enhanced design criteria are very weak. In this study, steel grid shear wall is proposed as a solution of seismic retrofit to ensure safety of the existing buildings for the earthquake. And the structural performance experiments were carried out under axial force and cyclic lateral loads. The two specimens were made of a reference RC frame and steel grid shear wall in-filled RC frame. The test setup configured with two dynamic actuators, for the axial force with a 500kN capacity actuator and for the cyclic lateral load applied with the 2,000kN actuator. Compared with control specimen, the strength, stiffness, ductility, energy dissipation capacity of the seismic retrofit structures is evaluated.
Experimental Study on the Temperature Dependency of Full Scale Low Hardness Lead Rubber Bearing
Park, Jin Young ; Jang, Kwang-Seok ; Lee, Hong-Pyo ; Lee, Young Hak ; Kim, Heecheul ;
Journal of the Computational Structural Engineering Institute of Korea, volume 25, issue 6, 2012, Pages 533~540
DOI : 10.7734/COSEIK.2012.25.6.533
Rubber laminated bearings with lead core are highly affected by changes in temperature because key materials which are rubber and lead have temperature dependencies. In this study, two full scale LRB(D800, S=5) are manufactured and temperature dependency tests on shear properties are accomplished. The shear properties at the 3rd cycle are used at
respectively. The double shear configuration, simultaneously testing two pieces, is applied for compression shear test in order to minimize the friction effects due to the test machine, described in ISO 22762-1:2010. Characteristic strength, post-yield stiffness, effective stiffness, equivalent damping ratio are estimated and presented coefficient due to the temperature changes.
A Study on the Calculation Method for Flexural Strength of One-way Hollow Slabs
Kim, Hyun-Su ; Lim, Jun-Ho ; Kang, Joo-Won ;
Journal of the Computational Structural Engineering Institute of Korea, volume 25, issue 6, 2012, Pages 541~548
DOI : 10.7734/COSEIK.2012.25.6.541
The hollow slab has advantages that its self-weight does not greatly increase notwithstanding the increase of its thickness and its flexural performance does not significantly degrade in comparison with general reinforced concrete slab. However, the utilization of the hollow slab is currently being underestimated in spite of structural system that enables economic design of building and construction of eco-friendly structure. the significant reasons for this situation is that the method of structural analysis and design for hollow slab is not generalized. In this study, to consider practical compressive zone of hollow slab, the equation for its flexural strength is proposed by the volume of compressive stress block according to neutral axis location in hollow section assumed. Existing estimation method of flexural strength of hollow slab considering only compressive zone above hollow part is evaluated as the most conservative method and the method estimating flexural strength by two alternative cross-section of hollow slab is evaluated as more practical method.
Level Set based Topological Shape Optimization of Phononic Crystals
Kim, Min-Geun ; Hashimoto, Hiroshi ; Abe, Kazuhisa ; Cho, Seonho ;
Journal of the Computational Structural Engineering Institute of Korea, volume 25, issue 6, 2012, Pages 549~558
DOI : 10.7734/COSEIK.2012.25.6.549
A topology optimization method for phononic crystals is developed for the design of sound barriers, using the level set approach. Given a frequency and an incident wave to the phononic crystals, an optimal shape of periodic inclusions is found by minimizing the norm of transmittance. In a sound field including scattering bodies, an acoustic wave can be refracted on the obstacle boundaries, which enables to control acoustic performance by taking the shape of inclusions as the design variables. In this research, we consider a layered structure which is composed of inclusions arranged periodically in horizontal direction while finite inclusions are distributed in vertical direction. Due to the periodicity of inclusions, a unit cell can be considered to analyze the wave propagation together with proper boundary conditions which are imposed on the left and right edges of the unit cell using the Bloch theorem. The boundary conditions for the lower and the upper boundaries of unit cell are described by impedance matrices, which represent the transmission of waves between the layered structure and the semi-infinite external media. A level set method is employed to describe the topology and the shape of inclusions. In the level set method, the initial domain is kept fixed and its boundary is represented by an implicit moving boundary embedded in the level set function, which facilitates to handle complicated topological shape changes. Through several numerical examples, the applicability of the proposed method is demonstrated.
Level Set Based Topological Shape Optimization of Hyper-elastic Nonlinear Structures using Topological Derivatives
Kim, Min-Geun ; Ha, Seung-Hyun ; Cho, Seonho ;
Journal of the Computational Structural Engineering Institute of Korea, volume 25, issue 6, 2012, Pages 559~567
DOI : 10.7734/COSEIK.2012.25.6.559
A level set based topological shape optimization method for nonlinear structure considering hyper-elastic problems is developed. To relieve significant convergence difficulty in topology optimization of nonlinear structure due to inaccurate tangent stiffness which comes from material penalization of whole domain, explicit boundary for exact tangent stiffness is used by taking advantage of level set function for arbitrary boundary shape. For given arbitrary boundary which is represented by level set function, a Delaunay triangulation scheme is used for current structure discretization instead of using implicit fixed grid. The required velocity field in the actual domain to update the level set equation is determined from the descent direction of Lagrangian derived from optimality conditions. The velocity field outside the actual domain is determined through a velocity extension scheme based on the method suggested by Adalsteinsson and Sethian(1999). The topological derivatives are incorporated into the level set based framework to enable to create holes whenever and wherever necessary during the optimization.
Sleeper Spacing Optimization for Vibration Reduction in Rails
Batjargal, Sodbilig ; Abe, Kazuhisa ; Koro, Kazuhiro ;
Journal of the Computational Structural Engineering Institute of Korea, volume 25, issue 6, 2012, Pages 569~577
DOI : 10.7734/COSEIK.2012.25.6.569
In this study, a theoretical investigation of optimized sleeper spacing which can suppress resonances of a railway track is attempted. To achieve this, we introduced a minimization problem in which the objective function is given by the wave transmittance and the design variable is defined by sleeper distribution. In the analysis the rail is modeled by a Timoshenko beam and the sleeper is represented by a mass. The infinite track analysis is realized by attaching the transmitting boundaries at both ends of the finite optimization region. Through numerical analyses the sleeper spacing effective in reduction of the transmittance is discussed. Furthermore, the feasibility of the proposed method is validated in the aspect of vibration reduction through response analyses for a harmonic load.