• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.5
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• pp.631-640
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• 2013

This paper provides a comparison of the J-integral estimation method under combined primary and secondary stress in the R6, RCC-MR A16 code. The comparisons of each code are based on finite element analysis using ABAQUS with regard to the crack shape, crack depth, and magnitude of secondary load. The estimate of the R6 code is conservative near $L_r=1$, and that of the RCC-MR A16 code is conservative near $L_r=0$. As a result, this paper proposes a modified method of J-integral estimation in the R6, RCC_MR A16 code. The J-integral using the modified method corresponds to the finite element analysis result.

• Steel and Composite Structures
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• v.43 no.2
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• pp.271-278
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• 2022

Buckling is one of the most critical phoneme in the design of steel structures. Lateral torsional buckling (LTB) is particularly significant for slender beams generally subjected to loading in plane. The web distortion effects on LTB are not addressed explicitly in standards for flexural design of steel I-section members. Hence, the present study is focused to predict the influence of the web distortion on the elastic (L_r) limiting lengths given in American Institute of Steel Construction (AISC) code for the lateral torsional buckling (LTB) behavior of steel beams due to no provision in the code for consideration of web distortion. For this aim, the W44x335 beam is adopted in the buckling analysis carried out by the ABAQUS finite element (FE) program since it is one of the most critical sections in terms of lateral torsional buckling (LTB). The strain results at mid-height of the web at mid-span of the beam are taken into account as the monitoring parameters. The web strain results are found to be relatively greater than the yield strain value when L/L_r is equal to 1.0. In other words, the ratio of L/L_r is estimated from the numerical analysis to be about 1.5 when the beam reaches its first yielding at mid-span of the beam at mid-height of the section. Due to the effect of web distortion, the elastic limiting length (L_r) from the numerical analysis is obtained to be considered as greater than the calculated length from the code formulation. It is suggested that the formulations of the limiting length proposed in the code can be corrected considering the influence of the web distortion. This correction can be a modification factor or a shape factor that reduces sectional slenderness for the LTB formulation in the code.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.1
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• pp.1-8
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• 2015

In this paper, computational evaluation method for fatigue crack growth rate(FCGR) based on material viscoplastic-damage model is proposed. Viscoplastic-damage model expressing material constitutive behavior of 7% nickel steel is introduced and is implemented into commercial finite element analysis(FEA) code, ABAQUS, as a user defined material subroutine(UMAT) for application in the FEA environments. Verification of developed UMAT and material parameters of material model are carried out by uniaxial tensile test simulations of 7% nickel steel. Moreover, jump-in-cycles procedure and rearrangement of critical damage are employed and also implemented to the ABAQUS UMAT for fatigue damage analysis. Typical FCGR test results such as relationship between crack length and number of cycles and relationship between da/dN and ${\Delta}K$ could be obtained from FCGR test simulation using developed UMAT and these results are compared with experimental results in order to verify of proposed computational method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.4
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• pp.1-9
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• 2021

A60 class deck penetration piece is a fire-resistance apparatus installed on the deck compartment to protect lives and prevent flame diffusion in fire accidents. In case that the A60 piece is newly developed or its initial design is revised, it is important to verify the fire resistance performance using a fire test procedure (FTP) code. In this paper, transient heat transfer analysis was carried out to evaluate the fire resistance design compatibility of the newly devised A60 piece. The analysis results were verified via a fire test. The heat transfer characteristics were also investigated by comparing design specifications, such as diameter, internal configuration, and material type. The analysis was performed using ABAQUS/Implicit, and the fire test was performed according to the FTP code. The fire resistance performance of the A60 pieces satisfied the safety of life at sea convention regulation. The material type was the most important design specification for the A60 piece. Based on the maximum test temperature, the measured temperature of SUS316L material was 25% lower than that of S45C on average. The differences between thermal conductivity and specific heat of each material were 17% and 58%, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.2 s.233
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• pp.253-261
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• 2005

In decades, a substantial body of work on a unified viscoplastic model which considers the mechanism of plastic deformation and creep deformation has developed. The systematic scheme for numerical analysis of unified model is necessary because the dominant failure mechanism is the defect growth and coalescence in materials. In the present study, the unified viscoplastic model for materials with defects suggested by Suquet and Michel was employed for numerical analysis. The constitutive equations are integrated based on the generalized mid-point rule and implemented into a finite element program (ABAQUS) by means of user-defined subroutine (UMAT). To evaluate the validity of the developed UMAT code and the assessment of the adopted viscoplastic model, the results obtained from the UMAT code was compared with the numerical reference solution and experimental data. The unit cell analysis also has been investigated to study the effect of strain rate, temperature, stress triaxiality and initial defect volume fraction on the growth and coalescence of the defect.

• Advances in concrete construction
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• v.9 no.1
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• pp.43-54
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• 2020

This paper presents an innovative stress-function variational approach in formulating the interfacial shear and normal stresses in an externally bonded concrete joint using carbon fiber-reinforced plastic (CFRP) plies. The joint is subjected to surface traction loadings applied at both ends of the concrete substrate layer. By introducing two interfacial shear and normal stress functions on the CFRP-concrete interface, based on Euler-Bernoulli beam idea and static stress equations of equilibrium, the entire stress fields of the joint were determined. The complementary strain energy was minimized in order to solve the governing equation of the joint. This yields an ordinary differential equation from which the interfacial normal and shear stresses were proposed explicitly, satisfying all the multiple traction boundary conditions. Lamination theory for composite materials was also employed to obtain the interfacial stresses. The proposed approach was validated by the analytic models in the literature as well as through a comprehensive computational code generated by the authors. Furthermore, a numerical verification was carried out via the finite element software ABAQUS. In the end, a scaling analysis was conducted to analyze the interfacial stress field dependence of the joint upon effective issues using the devised code.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.5
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• pp.488-496
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• 2003

To establish nondestructive test method for rocket motor assembly with rubber and aerospace composite materials, practicable quality control acoustic emission test method is presented. Structural analysis for motor assembly is performed by ABAQUS code and analysis output result is confirmed by strain gage and AE data. Various specimens were tested and analyzed using strain gage and acoustic emission data. The hit rate of acoustic emission was closely related with case/rubber debonding. This report also describes practicable acoustic emission nondestructive method for evaluating motor case assembly quality assurance in the industrial field.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1690-1695
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• 2007

Lightweight metallic truss structures with open, periodic cell are currently being investigated because of their multi-functionality such as thermal management and load bearing. The Kagome truss PCM has been proved that it has higher resistance to plastic buckling, more plastic deformation energy and lower anisotropy than other truss PCMs. The subject of this paper is an examination of the failure mechanism of Wire woven Bulk Kagome(WBK). To address this issue, the out-of-plane compressive responses of the WBK has been measured and compared with theoretical and finite element (FE) predictions. For the experiment, 2 multi-layered WBK are fabricated and 3 specimens are prepared. For the theoretical analysis, the brazed joints of each wire in WBK are modeled as the pin-joint. Then, the peak stress of compressive behavior and elastic modulus are calculated based on the equilibrium equation and energy method. The mechanical structure with five by five cells on the plane are constructed is modeled using the commercial code, PATRAN 2005. and the analysis is achieved by the commercial FE code ABAQUS version 6.5 under the incremental theory of plasticity.

• Advances in concrete construction
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• v.10 no.4
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• pp.289-299
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• 2020

A reliability analysis of the axial compressive load bearing capacity of postfire reinforced concrete (RC) columns strengthened with carbon fiber reinforced polymer (CFRP) sheets was presented. A 3D finite element (FE) model was built for heat transfer analysis using software ABAQUS. Based on the temperature distribution obtained from the FE analysis, the residual axial compressive load bearing capacity of RC columns was worked out using the section method. Formulas for calculating the residual axial compressive load bearing capacity of the columns after fire exposure and the axial compressive load bearing capacity of postfire columns retrofitted with CFRP sheets were developed. Then the Monte Carlo method was used to analyze the reliability of the axial compressive load bearing capacity of the RC columns retrofitted with CFRP sheets using a code developed in MATLAB. The effects of fire exposure time, load ratio, number of CFRP layers, concrete cover thickness, and longitudinal reinforcement ratio on the reliability of the axial compressive load bearing capacity of the columns after fire were investigated. The results show that within 60 minutes of fire exposure time, the reliability index of the RC columns after retrofitting with two layers of CFRPs can meet the requirements of Chinese code GB 50068 (GB 2001) for safety level II. This method is effective and accurate for the reliability analysis of the axial load bearing capacity of postfire reinforced concrete columns retrofitted with CFRP.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.9
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• pp.165-173
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• 1996

The dimensional accuracy of a final product is mainly affected by elastic die deformation during the forging and elastic recovery after the ejection in cold forging process. The investigations on elastic recovery are not so much as those of elastic die deformation. The elastic recovery can be determined by using the elastic-plalstic finite element analysis, but, this method has some limits such as poor conver- gence and long computational time, etc. In this paper, a theoretical analysis for predicting the elastic recovery of a final product in axi-symmetric forging process by using the rigid-plastic finite element method is presented. The rigid-plastic finite element analysis of a cold forward extrusion process involving loading, ejecting process is accomplished by rigid-plastic FE code, DEFORM. The effect of elastic die deformation on the final product dimenmsion is also considered. The calculated elastic recovery is compared is compared with the analysis result of elastic-plastic FE code. ABAQUS.