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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 22, Issue 6 - Dec 2009
Volume 22, Issue 5 - Oct 2009
Volume 22, Issue 4 - Aug 2009
Volume 22, Issue 3 - Jun 2009
Volume 22, Issue 2 - Apr 2009
Volume 22, Issue 1 - Feb 2009
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Finite Element Based Edge Crack Analysis of Silicon-Steel Sheet in Cold Rolling
Byon, Sang-Min ; Lee, Jae-Hyun ; Kim, Sang-Rok ; Jang, Yun-Chan ; Na, Doo-Hyun ; Lee, Jong-Bin ; Lee, Gyu-Taek ; Song, Gil-Ho ; Lee, Sung-Jin ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 6, 2009, Pages 511~517
In this paper an finite element approach for the edge crack analysis of silicon-steel sheet during cold rolling is presented. Based on the damage mechanics, the proposed approach follows the analysis steps which are composed of damage initiation, damage evolution and fracture. Through those steps, we can find out the initiation instant of crack and resulting propagated length and shape of the crack. The material constants related to fracture is experimentally obtained by tension tests using standard sheet-type specimen and notched sheet-type specimen. To evaluate the prediction accuracy, we performed a pilot rolling test with a initially notched sheets. It is shown that the results obtained by the approach converged to the experimental one concerning about the direction and length of propagated crack. The capability of the proposed one is demonstrated through the application to the actual silicon-steel rolling mill.
Numerical Simulations of Crack Initiation and Propagation Using Cohesive Zone Elements
Ha, Sang-Yul ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 6, 2009, Pages 519~525
In this study a cohesive zone model was used to simulate the delamination phenomena which occurs by a successive crack initiation and propagation in composite laminates. The cohesive zone model was incorporated to the classical finite element method via cohesive element formulation and then implemented into the user-subroutine UEL of a commercial finite element program Abaqus. To validate the formulation and implementation of the cohesive element the finite element results were compared with the experimental data of double cantilever beam and end notched flexure tests. The numerical results well agree with the experimental load-displacement curves. Also the effect of the elastic stiffness and the size of the cohesive element on the global load-displacement curves were studied numerically. To minimize the mesh-dependency of the crack propagation path and eliminate the zig-zag patterns in the load-displacement curve, cohesive elements should be refined at the crack-tip.
Parallel Computing Strategies for High-Speed Impact into Ceramic/Metal Plates
Moon, Ji-Joong ; Kim, Seung-Jo ; Lee, Min-Hyung ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 6, 2009, Pages 527~532
In this paper simulations for the impact into ceramics and/or metal materials have been discussed. To model discrete nature for fracture and damage of brittle materials, we implemented cohesive-law fracture model with a node separation algorithm for the tensile failure and Mohr-Coulomb model for the compressive loading. The drawback of this scheme is that it requires a heavy computational time. This is because new nodes are generated continuously whenever a new crack surface is created. In order to reduce the amount of calculation, parallelization with MPI library has been implemented. For the high-speed impact problems, the mesh configuration and contact calculation changes continuously as time step advances and it causes unbalance of computational load of each processor. Dynamic load balancing technique which re-allocates the loading dynamically is used to achieve good parallel performance. Some impact problems have been simulated and the parallel performance and accuracy of the solutions are discussed.
Failure Study for Knee Joint Through 3D FE Modeling Based on MR Images
Bae, Ji-Yong ; Park, Jin-Hong ; Song, Seong-Geun ; Park, Sang-Jin ; Jeon, In-Su ; Song, Eun-Kyoo ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 6, 2009, Pages 533~539
In this study, the femur, the tibia, the articular cartilage and the menisci are three dimensionally reconstructed using MR images of healthy knee joint in full extension of 26-year-old male. Three dimensional finite element model of the knee joint is fabricated on the reconstructed model. Also, the FE models of ligaments and tendons are attached on the biologically suitable position of the FE model. Bones, articular cartilages and menisci are considered as homogeneous, isotropic and linear elastic materials, and ligaments and tendons are modeled as truss element and nonlinear elastic springs. The numerical results show the contact pressure and the von Mises stress distribution in the soft tissues such as articular cartilages and menisci which can be regarded as important parameters to estimate the failure of the tissues and the pain of the patients.
Study of Crack Propagation and Absorbed Energy in Heat Affected Zone Using a Finite Element Method
Jang, Yun-Chan ; Lee, Young-Seog ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 6, 2009, Pages 541~548
In this study, Charpy impact test and numerical studies were performed to examine the effects of failure behavior and energy absorption on the notch position. For this purpose, carbon steel plate(SA-516 Gr. 70) with thickness of 25mm usually used for pressure vessel was welded by SMAW(Shielded Metal-Arc Welding)method and specimens were fabricated from the welded plate. The Charpy impact tests were then performed with specimens having different notch positions varying within HAZ. A series of three-dimensional FE analysis which simulates the Charpy test and crack propagation are carried out as well. We divided HAZ into two, three and four regions to apply mechanical properties of HAZ to FE-analys. Results reveal that the absorbed energies during impact test depend significantly on the notch position. To obtain the results of reliability, HAZ should be divided into at least three regions.
Plastic Loads of Mitred Bends under Internal Pressure and Bending Moment
Min, Sung-Hwan ; Kim, Yun-Jae ; Jeon, Jun-Young ; Lee, Kuk-Hee ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 6, 2009, Pages 549~555
Based on three-dimensional(3-D) finite element limit analyses, this paper provides limit and TES (Twice-Plastic Load) loads for mitred pipe bends under bending and pressure. The plastic limit loads are determined from FE limit analyses based on elastic-perfectly-plastic materials using the small and large geometry change option. A wide range of parameters related to the mitred bend geometry is considered. Based on the finite element results, closed-form approximations of plastic limit and TES plastic load solutions for mitred pipe bends under bending are proposed.
Effect of Similar Metal Weld & Preemptive Weld Overlay On Residual Stress of Repair Weldment In Surge Nozzle
Oh, Chang-Young ; Song, Tae-Kwang ; Shim, Kwang-Bo ; Kim, Ji-Soo ; Kim, Yun-Jae ; Lee, Kyung-Soo ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 6, 2009, Pages 557~564
Welding residual stress is occurred after welding process. Tensile residual stress is one factor of PWSCC. Repair welding usually happened during the manufacturing welding process. Repair welds cause strong tensile residual stress. In PWR, Repair weldments made by Alloy 82/182 is susceptible to PWSCC caused by tensile stress, material and environment. Therefore, mitigation of welding residual stress in weldments is important for reliable operating. PWOL is one of the methods for mitigation and verified for over twenty years. In this paper, residual stress distribution of repaired weldments and the effect of PWOL on mitigation is examined for surge nozzle.
Analysis of Mechanical Behavior and Fracture Toughness
on EGW Welded Joints for High Strength EH36-TMCP Ultra Thick Plate
Bang, Hee-Seon ; Bang, Han-Sur ; Joo, Sung-Min ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 6, 2009, Pages 565~572
This work intends to establish the reliability and fracture toughness
criterion of welded joints by EGW for high strength EH36-TMCP ultra thick plate. For this, firstly thermo elasto-plastic analysis has been carried out on two pass X-groove butt joint model to clarify the thermal and mechanical behaviour(residual stress, plastic strain, magnitude of stress and their distribution and production mechanism). Moreover, to establish fracture criterion, analysis of fracture toughness
has been performed under the notch machined and residual stress with the load condition on EGW welded joints. A quantitative fracture criterion for EGW welded joints is suggested by using
Finite Element Analysis of Harmonics Generation by Cracks
Yang, Seung-Yong ; Kim, Noh-Yu ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 6, 2009, Pages 573~577
When ultrasound propagates to a crack, transmitted and reflected waves are generated. These waves have useful information for the detection of the crack lying in a structure. In this paper, using finite element analysis, displacements round a inclined crack were obtained for 4 different inclination angles. Fourier transformation is applied to the results to research the frequency characteristics depending on the various locations around the crack. 2-dimensional plane stress model is considered, and finite element software ABAQUS/Explicit is used.
Finite Element Analysis for Evaluating the Performance of RC Beams Strengthened with SFRP Coating
Ha, Sung-Kug ; Yang, Bum-Joo ; Lee, Haeng-Ki ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 6, 2009, Pages 579~585
In this paper, a series of finite element analyzes were carried out to evaluate the performance of the RC beams strengthened with sprayed fiber reinforced polymer(SFRP) coating. A damage constitutive model based on the micromechanical constitutive model(Lee, 2001) in conjunction with the damage models(Lee 등, 2000) for SFRP coating was implemented into the finite element code ABAQUS. The present prediction results were compared with experimental data(Ha, 2007; Ha 등, 2009) to assess the accuracy of the damage constitutive model. It was concluded from the comparative study that the computational model developed by implementing the damage constitutive model into ABAQUS is suitable for the prediction of the performance of RC beams strengthened with SFRP coating.
Fiber Bridging Model Considering Probability Density Function of Fiber Inclined Angle in Engineered Cementitious Composites
Kang, Cheol-Ho ; Lee, Bang-Yeun ; Park, Seung-Bum ; Kim, Yun-Yong ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 6, 2009, Pages 587~596
The fiber bridging model is the crucial factor to predict or analyze the tensile behavior of fiber reinforced cementitious composites. This paper presents the fiber bridging constitutive law considering the distribution of fiber inclined angle and the number of fibers in engineered cementitious composites. The distribution of fiber inclined angle and the number of fibers are measured and analyzed by the image processing technique. The fiber distribution are considerably different from those obtained by assuming two- or three-dimensional random distributions for the fiber inclined angle. The simulation of the uniaxial tension behavior was performed considering the distribution of fiber inclined angle and number of fibers measured by the sectional image analysis. The simulation results exhibit multiple cracking and strain hardening behavior that correspond well with test results.
Nonlinear Biaxial Shear Model for Fiber-Reinforced Cementitious Composite Panels
Cho, Chang-Geun ; Kim, Yun-Yong ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 6, 2009, Pages 597~605
The present study has been proposed a model for the in-plane shear behavior of reinforced(Engineered Cementitious Composite(ECC) panels under biaxial stress states. The model newly considers the high-ductile tensile characteristic of cracked ECC by its multiple micro-cracking mechanism, the compressive strain-softening characteristic of cracked ECC, and the shear transfer mechanism in the cracked interface of ECC element. A series of numerical analyses were performed, and the predicted curves were compared with experimental results. The proposed in-plane shear model, R-ECC-MCFT, was found to be well matched with the experimental results, and it was also demonstrated that reinforced ECC panel showed more improved in-plane shear strength and post peak behavior, in comparing with the conventional reinforced concrete panel.
Chloride Penetration into Concrete in Tidal Zone by Diffusion-Convection Analysis
Kim, Ki-Hyun ; Cha, Soo-Won ; Jung, Hyung-Mok ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 6, 2009, Pages 607~615
Analysis of chloride penetration into concrete is performed considering the repeated wetting and drying conditions of tidal zone, by means of the developed finite element program which enables the diffusion-convection analysis to be conducted. Heat conduction and moisture diffusion are also included in the finite element analysis program in order that their effects to chloride penetration may be considered. For the efficiency of calculation, the analyses of temperature, relative humidity and free chloride concentration are conducted successively in that order, by treating the convection of chloride due to moisture diffusion as an source or sink term. By comparing the analysis result from finite element analysis, where main variable is a wetting and drying period, with the chloride profiles from ACI Life-365 method, it is shown that the Life-365 method gives an accurate result for the submerged zone but does not consider the differences of wetting and drying period. To obtain an accurate chloride profile in the tidal zone, it is confirmed that the diffusion-convection finite element analysis should be applied.
Residual Stresses Analysis due to Volumetric Changes in Long-term Autogenous Expansive Concrete
Cha, Soo-Won ; Jang, Bong-Seok ; Oh, Byung-Hyun ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 6, 2009, Pages 617~625
This study is devoted to the problems of thermal and autogenous expansion stresses in order to avoid cracking using chemically prestressing method. The chemical prestress can be induced by autogenous expansion characteristics of MgO concrete made in specific burning temperature. The volume change induced cracking has great influence on the long-term durability and serviceability. To evaluate risk of cracking, the computer programs for analysis of thermal and autogenous expansion stresses were developed. In these 3-D finite element procedures, long-term autogenous expansive deformation is modeled and its resultant stress is calculated and then verified by comparison with manual calculation results. In this study, the stress development is related to thermal and autogenous expansive deformation. Using the developed program, residual stresses of MgO concrete were compared and analysed in the example From the numerical results it is found that long-term, and temperature dependent expansive concrete with light-burnt MgO is most effective in controlling the risk of cracking of mass concrete because it has high temperature for long period. The developed analysis program can be efficiently utilized as a useful tool to evaluate the thermal and autogenous expansion stresses in mass concrete structures with lightly burnt MgO.
Behavior of Orthotropic Composite Plate Due to Random Poisson's Ratio
Noh, Hyuk-Chun ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 6, 2009, Pages 627~637
Composite materials have been employed in the various engineering applications due to high mechanical performances including high strength-weight ratio and high degree of free formability. Due to complex manufacturing process, however, it can have intrinsic randomness in the material constants which affect the deterministic behavior of the composite structures. In this study, we suggest a formulation for stochastic finite element analysis considering the spatial randomness of Poisson's ratio. Considering the reciprocal relation between elastic moduli and Poisson's ratios in the two mutually orthogonal axes, one of two values of Poisson's ratio can be expressed in terms of the other. Using this, the relation between stress resultants and strains is derived in the ascending order of power of the stochastic field function, which can be directly used in the formulation to obtain the coefficient of variation of responses. The adequacy of the proposed scheme is demonstrated by comparison with the results of Monte Carlo analysis.
Numerical Simulation for the Variation of the Fiber Orientation Distribution according to the Flow of High-Flow Steel-Fiber Reinforced Mortar
Kang, Su-Tae ; Kim, Jin-Keun ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 6, 2009, Pages 639~646
High-flow steel-fiber reinforced mortar may induce a certain fiber orientation distribution in the process of placing and thus have an influence on the tensile properties. In this paper, the variation of the fiber orientation distribution according to the flow of high-flow steel-fiber reinforced mortar was estimated in numerical simulation. The analytical results present that the major variation of fiber orientation distribution is made within 150mm of flow distance, thereafter the tendency of the fiber orientation distribution is not noticeable even though the peak of distribution density in the orientation parallel to the flow direction get bigger along the distance. Considering the close relation between the fiber orientation and the tensile behavior of composite, prediction of fiber orientation distribution make it possible to predict the variation in the tensile behavior of high-flow steel-fiber reinforced mortar according to the flow.