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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 27, Issue 6 - Dec 2014
Volume 27, Issue 5 - Oct 2014
Volume 27, Issue 4 - Aug 2014
Volume 27, Issue 3 - Jun 2014
Volume 27, Issue 2 - Apr 2014
Volume 27, Issue 1 - Feb 2014
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Density-based Topology Design Optimization of Piezoelectric Crystal Resonators
Ha, Youn Doh ; Byun, Taeuk ; Cho, Seonho ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 2, 2014, Pages 63~70
DOI : 10.7734/COSEIK.2014.27.2.63
Design sensitivity analysis and topology design optimization for a piezoelectric crystal resonator are developed. The piezoelectric crystal resonator is deformed mechanically when subjected to electric charge on the electrodes, or vice versa. The Mindlin plate theory with higher-order interpolations along thickness direction is employed for analyzing the thickness-shear vibrations of the crystal resonator. Thin electrode plates are masked on the top and bottom layers of the crystal plate in order to enforce to vibrate it or detect electric signals. Although the electrode is very thin, its weight and shape could change the performance of the resonators. Thus, the design variables are the bulk material densities corresponding to the mass of masking electrode plates. An optimization problem is formulated to find the optimal topology of electrodes, maximizing the thickness-shear contribution of strain energy at the desired motion and restricting the allowable volume and area of masking plates. The necessary design gradients for the thickness-shear frequency(eigenvalue) and the corresponding mode shape(eigenvector) are computed very efficiently and accurately using the analytical design sensitivity analysis method using the eigenvector expansion concept. Through some demonstrative numerical examples, the design sensitivity analysis method is verified to be very efficient and accurate by comparing with the finite difference method. It is also observed that the optimal electrode design yields an improved mode shape and thickness-shear energy.
Numerical Simulation based on SPH of Bullet Impact for Fuel Cell Group of Rotorcraft
Kim, Hyun Gi ; Kim, Sung Chan ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 2, 2014, Pages 71~78
DOI : 10.7734/COSEIK.2014.27.2.71
There is a big risk of bullet impact because military rotorcraft is run in the battle environment. Due to the bullet impact, the rapid increase of the internal pressure can cause the internal explosion or fire of fuel cell. It can be a deadly damage on the survivability of crews. Then, fuel cell of military rotorcraft should be designed taking into account the extreme situation. As the design factor of fuel cell, the internal fluid pressure, structural stress and bullet kinetic energy can be considered. The verification test by real object is the best way to obtain these design data. But, it is a big burden due to huge cost and long-term preparation efforts and the failure of verification test can result in serious delay of a entire development plan. Thus, at the early design stage, the various numerical simulations test is needed to reduce the risk of trial-and-error together with prediction of the design data. In the present study, the bullet impact numerical simulation based on SPH(smoothed particle hydrodynamic) is conducted with the commercial package, LS-DYNA. Then, the resulting equivalent stress, internal pressure and bullet's kinetic energy are evaluated in detail to examine the possibility to obtain the configuration design data of the fuel cell.
Nonlinear Finite Element Analysis on Global and Distortional Buckling of Cold-Formed Steel Members
Kang, Hyun Koo ; Rha, Chang Soon ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 2, 2014, Pages 79~86
DOI : 10.7734/COSEIK.2014.27.2.79
This paper presents modelling approaches for the global and distortional buckling of cold-formed built-up steel sections using the finite element software packages, ANSYS and ABAQUS. Thin thickness of the cold-formed steel causes nonlinear behaviour due to local and distortional buckling, thus careful consideration is required in modelling for numerical analysis. Implicit static modelling using ANSYS provides unstable numerical results as the load approaches the limit point but explicit dyamic modelling with ABAQUS is able to display the behaviour even in post-buckling range. Meanwhile, axial load capacities obtained from the numerical analysis show higher values than the experimental axial capacities, due to eccentricity during the test. Axial capacities of the cold-formed steel obtained through numerical analysis requires reduction factor, and this paper suggests 0.88 for the factor.
Force-based Coupling of Peridynamics and Classical Elasticity Models
Ha, Youn Doh ; Byun, Taeuk ; Cho, Seonho ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 2, 2014, Pages 87~94
DOI : 10.7734/COSEIK.2014.27.2.87
In solid mechanics, the peridynamics theory has provided a suitable framework for material failure and damage propagation simulation. Peridynamics is computationally expensive since it is required to solve enormous nonlocal interactions based upon integro-differential equations. Thus, multiscale coupling methods with other local models are of interest for efficient and accurate implementations of peridynamics. In this study, peridynamic models are restricted to regions where discontinuities or stress concentrations are present. In the domains characterized by smooth displacements, classical local models can be employed. We introduce a recently developed blending scheme to concurrently couple bond-based peridynamic models and the Navier equation of classical elasticity. We demonstrate numerically that the proposed blended model is suitable for point loads and static fracture, suggesting an alternative framework for cases where peridynamic models are too expensive, while classical local models are not accurate enough.
Verification of Linear FE Model for Nonlinear SSI Analysis by Boundary Reaction Method
Lee, Gye Hee ; Hong, Kwan Young ; Lee, Eun Haeng ; Kim, Jae Min ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 2, 2014, Pages 95~102
DOI : 10.7734/COSEIK.2014.27.2.95
In this paper, a coupling scheme for applying finite element analysis(FEA) programs, such as, LS-DYNA and MIDAS/Civil, to a nonlinear soil structure interaction analysis by the boundary reaction method(BRM) is presented. With the FEA programs, the structure and soil media are discretized by linear or nonlinear finite elements. To absorb the outgoing elastic waves to unbounded soil region as much as possible, the PML elements and viscous-spring elements are used at the outer FE boundary, in the LS-DYNA model and in MIDAS/Civil model, respectively. It is also assumed that all the nonlinear elements in the problem are limited to structural region. In this study, the boundary reaction forces for the use in the BRM are calculated using the KIESSI-3D program by solving soil-foundation interaction problem subjected to incident seismic waves. The effectiveness of the proposed approach is demonstrated with a linear SSI seismic analysis problem by comparing the BRM solution with the conventional SSI solution. Numerical comparison indicates that the BRM can effectively be applied to a nonlinear soil-structure analysis if motions at the foundation obtained by the BRM for a linear SSI problem excluding the nonlinear structure is conservative.
Assessment of the Internal Pressure Fragility of the PWR Containment Building Using a Nonlinear Finite Element Analysis
Hahm, Daegi ; Park, Hyung-Kui ; Choi, In-Kil ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 2, 2014, Pages 103~111
DOI : 10.7734/COSEIK.2014.27.2.103
In this study, the probabilistic internal pressure fragility analysis was performed by using the non-linear finite element analysis method. The target structure is one of the containment buildings of typical domestic pressurized water reactors(PWRs). The 3-dimensional finite element model of the containment building was developed with considering the large equipment hatches. To consider uncertainties in the material properties and structural capacities, we performed the sensitivity analysis of the ultimate pressure capacity with respect to the variation of four important uncertain parameters. The results of the sensitivity analysis were used to the selection of the probabilistic variables and the determination of their probabilistic parameters. To reflect the present condition of the tendon pre-stressing force, the data of the pre-stressing force acquired from the in-service inspections of tendon forces were used for the determination of the median value. Two failure modes(leak, rupture) were considered and their limit states were defined to assess the internal pressure fragility of target containment building. The internal pressure fragilities for each failure mode were evaluated in terms of median internal pressure capacity, high confidence low probability of failure(HCLPF) capacity, and fragility curves with respect to the confidence levels. The HCLPF capacity was 115.9 psig for leak failure mode, and 125.0 psig for rupture failure mode.
Behavior of Prestressed Concrete Panels under Blast Load
Jo, Eunsun ; Kim, Min Sook ; Park, Jong Yil ; Lee, Young Hak ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 2, 2014, Pages 113~120
DOI : 10.7734/COSEIK.2014.27.2.113
This paper showed the behavior of the material four members under blast load, and are trying to demonstrate the effectiveness of the prestress. The prestressed concrete structures are on the rise, but there is little research in this regard explosion. Concrete panels, Reinforced concrete panels, the prestressed concrete panels, and the prestressed reinforced concrete panels was set variables. TNT 500 kg was an explosion in the distance 3m. Analysis, concrete and reinforced concrete members after an explosion occurred continuously deformed, but the including prestressed panel deformation occurs only at the beginning of the explosion were able to see the results. That is, the including prestressed member is prestressed against blast load cracking and destruction can be seen that control.
Evaluation of Shear Strength for Reinforced Flat Plates Embedded with GFRP Plates
Hwang, Seung Yeon ; Kim, Min Sook ; Lee, Young Hak ; Kim, Heecheul ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 2, 2014, Pages 121~128
DOI : 10.7734/COSEIK.2014.27.2.121
In this study, The purpose of this study is to experimentally investigate the shear behavior of reinforced flat plate embedded with GFRP(glass fiber reinforced polymer) plate with openings. The GFRP shear reinforcement is manufactured into a plate shape with several openings to ensure perfect integration with concrete. The test was performed on 7 specimens. the parameters include the type of reinforcement and amount of the shear reinforcement., From the test, we analysed the crack, failure mode, Strain, load-displacement graph. a calculation of the shear strength of reinforced flat plate with GFRP plate based on the ACI 318-11 was compared with the test results. The results of the experiment indicate that GFRP plate is successfully applied as a shear reinforcement in the flat plate under punching shear.