• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3732-3744
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• 2022

To investigate the effects of ocean conditions on the thermal stress and deformation caused by thermal stratification of a pressurizer surge line in a floating nuclear power plant (FNPP), the finite element simulation platform ANSYS Workbench is utilized to conduct the fluid-solid-thermal coupling transient analysis of the surge line under normal "wave-out" condition (no motion) and under ocean conditions (rolling and pitching), generating the transient response characteristics of temperature distribution, thermal stress and thermal deformation inside the surge line. By comparing the calculated results for the three motion conditions, it is found that ocean conditions can significantly improve the thermal stratification phenomenon within the surge line, but may also result in periodic oscillations in the temperature, thermal stress, and thermal deformation of the surge line. Parts of the surge line that are more susceptible to thermal fatigue damage or failure are determined. According to calculation results, the improvements are recommended for pipeline structure to reduce the effects of thermal oscillation caused by ocean conditions. The analysis method used in this study is beneficial for designing and optimizing the pipeline structure of a floating nuclear power plant, as well as for increasing its safety.

• Computers and Concrete
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• v.32 no.5
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• pp.439-454
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• 2023

In this article, the surface stress effects on the buckling analysis of the annular sandwich plate is developed. The proposed plate is composed of two face layers made of carbon nanotubes (CNT) reinforced composite with assuming of fully bonded to functionally graded porous core. The generalized rule of the mixture is employed to predict the mechanical properties of the microcomposite sandwich plate. The derived potentials energy based on higher order shear deformation theory (HSDT) and modified couple stress theory (MCST) is solved by employing the Ritz method. An exact analytical solution is presented to calculate the critical buckling loads of the annular sandwich plate. The predicted results are validated by carrying out the comparison studies for the buckling analysis of annular plates with those obtained by other analytical and finite element methods. The effects of various parameters such as material length scale parameter, core thickness to total thickness ratio (hc/h), surface elastic constants based on surface stress effect, various boundary condition and porosity distributions, size of the internal pores (e0), Skempton coefficient and elastic foundation on the critical buckling load have been studied. The results can be served as benchmark data for future works and also in the design of materials science, injunction high-pressure micropipe connections, nanotechnology, and smart systems.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.263-266
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• 2008

This paper is concerned with the analysis of elasto-plastic stress waves in a mode I semi-infinite cracked solid subjected to Heaviside pulse load. This study adopts a time-discontinuous variational integrator based on Hamiltonian in order to reduce the numerical dispersive and dissipative errors. This also utilizes an integration scheme of the constitutive model with 2nd-order accuracy which is formulated on the strain space for a rate and temperature dependent material model. Finite element analyses of elasto-plastic stress waves are carried out in order to compare the accuracy between a conventional Galerkin method and the time- discontinuous variational integrator.

• Transactions of Materials Processing
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• v.8 no.4
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• pp.364-373
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• 1999

For material characterization of semi-solid materials, backward extrusion process, which has been used in forming of hollow-sectioned products, was analyzed by the upper bound analysis in the current study. The existing kinematically admissible velocity field was applied to steady state at which there was no change in the assumed regions of velocity field. For unsteady state, new velocity field, as a function of dead zone angle, was proposed. Through the whole analysis, fiction between die and workpiece was also considered. It has been studied how the process variables, such as friction factor and punch velocity, and material parameters, such as strength coefficient, strain rate sensitivity could affect on analysis results. Finally, by the comparison with the finite element analysis, the reliability and efficiency of the proposed velocity field were discussed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.8-11
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• 2002

In this study, Automatic design program creates 3D solid models and constructs them. The method of making assembly model is two. One assembles the element made in automatic design program with hand, the other develops the automatic design program for creating assembly model. Automatic design program improves the convenience of user. In creating gears, involute ewe and Trochoidal fillet curve are made by mathematical development.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.848-851
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• 2002

In the field of automobile industry, lightweight problems are very important in terms of reducing fuel and protecting environment. To satisfy these demands, the attempt to substitute aluminum automobile components for cast steel part has been actively carried out. To fabricate the aluminum automobile suspension part that has the same mechanical properties with cast steel part, design conditions such as shape and dimension of part shall be established. Therefore in this study, shape and dimension conditions of suspension part were proposed. Aluminum automobile suspension part was fabricated by semi-solid die-casting process under the obtained design conditions. Moreover to evaluate the possibility of application to the automobile component, stress and fatigue analysis were performed by using ABAQUS S/W and compared with those of conventional automobile suspension part.

• Journal of the Korean Society of Industry Convergence
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• v.3 no.2
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• pp.107-114
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• 2000

Recently the studies on the vibration and the noise of a helical gear transmission have been focused on the many researchers. The manufacturing error and the deformation of the tooth profile, which generates the vibration and the noise of the gear transmission, are main factors. The major purpose of this study is to develop an optimal design program for reducing the vibration and the noise of the helical gear. To obtain the these results, we restrain the helical gear from the deformation of the tooth profile and increase the contact ratio within the optimal design program. Furthermore we made the three-dimensional solid modeling of the helical gear from the AutoCAD and the Pro/Engineer. This model will be available to generate the finite element model and the NC code.

• Journal of Ocean Engineering and Technology
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• v.12 no.3 s.29
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• pp.68-74
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• 1998

An increase of concrete construction in marine environments as well as an increasing use of marine aggregate at the mixing stage of concrete has provoked an important problem. A high concentration of chloride ion in the vicinity of steel bars in concrete is the principal cause of premature reinforcement corrosion in concrete structures. In this study, the behavior of chloride ions introduced into concrete from concrete surface by marine evironment was analysed. A mathematical model including the diffusion of chloride ion in aqueous phase of pores, the adsorption and desorption of chloride ions to and from the surface of solid phase of concrete and the chemical reactions of chloride ions with solid phase was presented. Finite element method was employed to carry out numerical analysis. The results of this study may be used to predict the onset of reinforcement corrosion and to identify the maximum limit of chloride ions contained in concrete admixtures.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.10a
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• pp.173-179
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• 1996

A computer simulation has been performed for the application to the elastoplastic stress analysis in a discontinuous composite solid. To obtain the internal field quantities of composite the micromechanics analysis and finite element analysis (FEA) were implemented. As the procedure the reasonably optimized FE mesh generations the appropriate imposition of boundary condition and the relevant postprocessing such as elastoplastic thermomechanical analysis were taken into account. For the numerical illustration an aligned axisymmetric single fiber model has been employed to assess field quantities. It was found that the proposed simulation methodology for stress analysis is applicable to the complicated inhomogeneous solid for the investigation of micromechanical behavior.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.269-274
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• 1997

Recently, premature reinforcement corrosion in concrete structures exposed to chloride containing environments has an important problem. This is due to an increasing use of marine aggregate of chloride containing admixture a the mixing stage and due to an increase of concrete construction in marine environments. In this study, the behavior of chloride ions introduced into concrete from concrete surface by a marine environment was modeled. The physicochemcial processes including the diffusion of chloride ion in aqueous phase of pores, the adsorption and desorption of chloride ions to and from the surface of solid phase of concrete, and the chemical reaction of chloride ion with solid phase were analyzed by using the finite element method. The results of this study may be used to predict the onset of reinforcement corrosion, and identify the maximum limit of chloride ions contained in admixtures.