• Composites Research
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• v.30 no.6
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• pp.410-415
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• 2017

This paper predicted deformation due to thermal residual stress in composites using finite element analysis. Temperature cycle, Model shape, Laminate angle, Stacking sequence, chemical shrinkage of resin, and thermal expansion are affect composite deformation. Compare the results of the analytical model with the actual model of the same shape. This paper suggests that the analytical results can be applied to actual Model.

• Journal of Energy Engineering
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• v.26 no.2
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• pp.1-11
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• 2017

While they are becoming more viable, synthetic natural gas (SNG) plants, with their high temperatures and pressures, are still heavily dependent on advancements in the state-of-the-art technologies. However, most of the current work in the literature is focused on optimizing chemical processes and process variables, with little work being done on relevant mechanical damage and maintenance engineering. In this study, a combination of pipe system stress analysis and detailed local stress analysis was implemented to prioritize the inspection locations for main pipes of SNG plant in accordance to ASME B31.3. A pipe system stress analysis was conducted for pre-selecting critical locations by considering design condition and actual operating conditions such as heat-up and cool-down. Identified critical locations were further analyzed using a finite element method to locate specific high-stress points. Resultant stress values met ASME B31.3 code standards for the gasification reactor and lower transition piece (bend Y in Fig.1); however, it is recommended that the vertical displacement of bend Y be restricted more. The results presented here provide valuable information for future risk based maintenance inspection and further safe operation considerations.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.4
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• pp.485-500
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• 2000

In this paper the adaptive crack propagation analysis based on the estimated local and global error in the element-free Galerkin (EFG) method is presented. It is possible to keep consistency and accuracy of analysis in each propagation step by adaptive analysis. The adaptivity analysis in crack propagation is achieved by adding and removing the node along the background integration cell that are refined or recovered as estimated error. These errors are obtained by calculating the difference between the values of the projected stresses and original EFG stresses. To evaluate the performance of proposed adaptive procedure, the convergence behavior is investigated lot several examples. The results of these examples show the efficiency of proposed scheme in crack propagation analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.167-175
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• 1988

The principle objective of this study is to evaluate the fatigue behavior of structural steel components of highway bridges subjected to service stresses. The main aspects of this investigation are; 1) a measurement and statistical analysis of service stress cycles observed in highway bridge. 2) fatigue tests under equivalent constant-amplitude(CA) loading and simulated variable-amplitude(VA) loading 3) a evaluation of the fatigue behavior under VA-loading by eqivalent root mean cube (RMC) stress range. Theoretically, the RMC model is adequate in evaluation of fatigue behavior under VA-loading, because the regression coefficient (m) of crack growth rate is 3 approximately. The result of fatigue test shows that the RMC model is fitter than the current RMS model in fatigue evaluation under VA-loading. The interaction effects and sequence effects under VA-loading affect little fatigue life of structural components. As the transition rate of stress ranges is higher, the crack growth rate is higher.

• Journal of the KSME
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• v.33 no.7
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• pp.600-613
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• 1993

유한요소법은 구조공학분야에서 발전하여 과학기술 전반에 통용되는 수치해석의 한 방법 또는 기술로서 각광받고 있다. 이 기법은 변분원리에 수학적 기초를 두는 미분 방정식의 수치해법의 하나라고 할 수 있다. 이 글에서는 고체역학 부문에 한정하여 유한요소법의 기본체계, 응력계산과 관련하여 중요 수치현상, 그리고 최근 국내외학계의 연구동향 및 상용 패키지 사용시 주의 사항에 관하여 언급한다.

• Journal of the Korea Convergence Society
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• v.11 no.11
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• pp.239-247
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• 2020

This study is about design and verification of stress reduction of bearings for wind turbines. In a slewing bearing having a typical four-contact structure, the contact point moves to the end of the raceway due to a large moment load, resulting in a stress concentration. A bearing was designed to reduce such contact point movement. The deformation behavior of typical ball bearings and newly designed bearings was calculated through finite element analysis under ultimate load by replacing the ball with a spring element. The contact stress between the ball and the raceway was calculated by finite element analysis by inputting the deformation behavior analysis result as a boundary condition. The effectiveness of the bearing stress analysis method using spring elements was verified through comparison of the contact stress according to the bearing structure.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.6
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• pp.409-413
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• 2013

In this paper, we device stress-diffusion full coupling multiscale analysis method for battery electrode simulation. In proposed method, the diffusive and mechanical properties of electrode material depend on Li concentration are estimated using density function theory(DFT) simulation. Then, stress-diffusion full coupling continuum formulation based on finite element method(FEM) is constructed with the diffusive and mechanical properties calculated from DFT simulation. Finally, silicon nanowire anode charge and discharge simulations are performed using the proposed method. Through numerical examples, the stress-diffusion full coupling method shows more resonable results than previous one way continuum analysis.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.3
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• pp.275-281
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• 2010

In this paper, the design optimization of structures with stress constraints is performed using isogeometric shape optimization method. The stress constraints have an important role in design optimization problems since stress concentration could result in structural failure. To represent exact geometry in analysis, the isogeometric analysis method uses the same basis functions as used in the CAD geometry. The geometrically exact model can be used in both stress and design sensitivity analyses so that it can yield more precise optimal design than finite element one. Through numerical examples, the isogeometric approach turns out to be effective in shape optimization problems under stress constraints.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.3
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• pp.511-521
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• 2002

A simple numerical modelling technique is proposed for estimating the shear stress distribution in beams of framed tube structures with multiple internal tubes. The structures arc analysed using a continuum approach in which each tube is individually modelled by a tube beam that accounts for the flexural and shear deformations, as well as the shear lag effects. The numerical analysis of shear stress is based on the mathematical analogy in conjunction with the elastic theory By simplifying assumptions regarding the form of strain distributions in external and internal tubes, the shear stress distributions are expressed in terms of a series of lineal functions of the second moments of area of the structures and the corresponding geometric and material properties, as well as the applied loads. Previous studies for axial stresses and shear lag phenomenon are further developed lot the numerical analysis of shear stresses in the tubes. The simplicity and accuracy of the proposed method are demonstrated through the solutions of throe numerical examples.

• Journal of the Korean Geotechnical Society
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• v.29 no.12
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• pp.77-85
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• 2013

Unsaturated slopes experience infiltration during rainfall and become unstable when saturated. On the viewpoint of unsaturated effective stress, as matric suction decreases, both effective stress and shear strength decrease, which declines slope stability consequently. This study is focused on describing effective stress based on suction stress. The actual slope failures are simulated to calculate factors of safety in the field of finite element stress. In the residual soils of Hadong and Pohang, unsaturated properties are evaluated by laboratory tests. For unsaturated slopes, analyses of infiltration, stress and stability were performed to simulate actual failures. Based on unsaturated effective stress principle, the stability of actual slopes could be evaluated successfully. It is verified for the effective stress concept to be applicable to the engineering practice on slope design which considers infiltration by rainfall.