• Journal of Power System Engineering
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• v.16 no.1
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• pp.78-83
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• 2012

The authors suggest the algorithm for the static analysis of a three dimensional solid structure by using the finite element-transfer stiffness coefficient method (FE-TSCM) and the hexahedral element of the finite element method (FEM). MATLAB codes were made by both FE-TSCM and FEM for the static analysis of three dimensional solid structure. They were applied to the static analyses of a very thick plate structure and a three dimensional solid structure. In this paper, as we compare the results of FE-TSCM with those of FEM, we confirm that FE-TSCM introducing the hexahedral element for the static analysis of a three dimensional solid structure is very effective from the viewpoint of the computational accuracy, speed, and storage.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.9 s.186
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• pp.149-155
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• 2006

This paper is concerned with the weight reduction of front side member of a vehicle considering the application of high strength steel sheet. The influence of steel sheet grade and thickness on the energy absorption, impact load and deformed shape of front side member is investigated by using reverse engineering and FE-analysis. The reverse engineering is applied to obtain 3D model of front side member from B.I.W for the FE simulation. FE analysis is carried out with commercial crash analysis SW PAM-CRASH. The crashworthiness of front side member is considerably improved with steel sheet strength and thickness increase. From the result of this study the weight reduction in automotive parts for the improvement of the fuel efficiency can be easily achieved with replacing high strength steel without deterioration of crashworthiness.

• Journal of KSNVE
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• v.10 no.6
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• pp.1009-1016
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• 2000

This paper describes the procedure of increasing the efficiency of experimental modal analysis and updating the quality of FE model using the scaled commercial vehicle frame. In this study, it was found that the experimental modal analysis could be more efficient when the measurements were made on the areas with high kinetic energies. Such areas could be located with the aid of FE modal analysis. Also, the number of measurement points could be decided by considering the dynamic characteristics of full FE model. The correlation of FE model and experimental modal analysis was assessed by the differences between the natural frequencies and MAC matrix, which is based on normal modes. These differences of modal parameters were reduced through the sensitivity and optimization analysis of which objective function consisted of the errors of natural frequencies and the diagonal terms of MAC matrix.

• Journal of Ocean Engineering and Technology
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• v.25 no.1
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• pp.61-66
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• 2011

According to recent figures, 35% of the world's blades are made using prepreg blades, by Vestas and Gamesa. They are the most advanced in the market today. In this study, we investigated the validity of the finite element method (FEM) applied to an FE analysis of a hybrid composite wind-turbine blade. Two methods were suggested for a composite FE analysis: using the equivalent properties of the composite or using stacking properties. FE analysis results using the stacking properties of the composite were in good agreement with results of using the equivalent properties. The difference between FE results was approximately 0.6~13.3%.

• Journal of the Mineralogical Society of Korea
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• v.19 no.4 s.50
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• pp.325-336
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• 2006

Domestic serpentinite is one of the important industrial minerals utilizing in the iron manufacturing company such as POSCO in Korea. Serpentinite is distributed in the Ulsan Fe deposit, Andong, Hongseong-Cheongyang, and Gapyeong areas. This study tries to interpret the relationship among the formation of carbonate rocks, iron mineralization, and serpentinite alteration throughout the study of field occurrence, mineralogy, and chemical compositions. Serpentine is formed by the break-down of olivine and pyroxene of parent peridotite. The serpentinization is inferred to be formed by the hydrothermal fluid derived from intruded Cretaceous granite and the addition of meteoric water. Variation of major oxides such as $SiO_2,\;Fe_2O_3$, and MgO in serpentinized rocks are controlled by the degree of serpentinization and Fe mineralization. Variation of $Al_2O_3$ and CaO contents of altered rocks is dependent on the amount of the residual minerals such as calcite and homblende, and on the degree of chloritization. The presence of carbonate rocks reported in the sedimentary origin or igneous origin (carbonatite) provided a geological environment to form skarn type Fe deposit regardless of its origin. The geological processes of Ulsan Fe deposits are inferred to be formed as the order of the formation of carbonate rocks ${\to}$ the intrusion of Cretaceous granite ${\to}$ serpentinization ${\to}$ Fe mineralization by the interprelation of field occurrence and mineralogical characteristics.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.1
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• pp.139-146
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• 2002

This paper provides validations of the reference stress based J and $C^{*}$ estimations, proposed in Part I, for inner, circumferential surface cracked pipes under internal pressure and global bending against detailed 3-D elastic-plastic and elastic-creep FE results. For this purpose, actual tensile properties of two typical stainless steels (TP304 and TP316) are used for elastic-plastic FE analyses and two realistic creep laws are used for elastic-creep FE analyses. For a total of twenty cases considered in this paper, agreements between the proposed reference stress based J and $C^{*}$ estimations and the FE results are excellent. More important aspect of the proposed estimations is that they can be used to estimate J and $C^{*}$ not only at the deepest point of the surface crack but also at an arbitrary point along the crack front.front.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.4
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• pp.310-320
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• 2009

In this paper, we estimate area-averaged solution of peening residual stress using a 3-D multi-impact symmetry-cell FE model. The symmetry-cell model includes factors reflecting peening phenomena and plastic shot. Area-averaged solution is much closer to XRD experimental solution than 4-node-averaged solution in plastic shot FE model. We then obtain FE Almen saturation curve corresponding to experimental Almen curve based on area-averaged solution. Using the curve, we obtain FE area-averaged solution in major peening materials, and compare the FE solution with experimental solution. In peening materials, surface, maximum compressive residual stress and deformation depth reach experimental solutions. Thus, FE Almen curve is useful for estimation of residual stress solution and could improve the efficiency of peening process. Consequently, it is confirmed that concept of area-averaged solution is the realistic analytical method for evaluation of peening residual stress.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.183-188
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• 2007

In this paper, we propose a 2D-FE model in single impact with combined physical factors to obtain a unique residual stress by shot peening. Applied physical parameters include elastic-plastic deformation of shot ball, material damping coefficients, strain rate, dynamic friction coefficients. Single impact FE model consists of 2D axisymmetric elements. The FE model with combined factors showed converged and unique distributions of surface stress, maximum compressive residual stress and deformation depth. Further, in contrast to the FE models with rigid shot and elastic deformable shot, FE model with plastic deformable shot produces residual stresses very close to experimental solutions by X-ray diffraction. We therefore validated the 2D FE model with combined peeing factors and plastic deformable shot. This FE model will be a base of the 3D FE model for residual stresses by multi-impact shot peening.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.424-429
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• 2008

Aircraft flutter analysis model consists of dynamic FE model and aerodynamic model. Dynamic FE model is composed of stiffness and mass model, and is used for the prediction of normal mode characteristics of the structure. Since aircraft flutter analysis is normally performed in the modal domain, dynamic FE model shall be constructed to describe the modal characteristics of the structure with sufficient accuracy. In this study, dynamic FE modeling method was described using full airframe FE model and structural and system weight data for aircraft flutter analysis. In addition, full airframe dynamic FE model for composite small aircraft was constituted for normal mode and flutter analysis, and the mass modeling results were compared with the target weight data to validate the mass modeling method proposed. Finally, full airframe flutter analysis of composite small aircraft was performed with the dynamic FE model and the aerodynamic model composed.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.610-622
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• 2021

The DECOVALEX project is one of the representative international cooperative projects to enhance the understanding of the complex Thermo-Hydro-Mechanical-Chemical(THMC) coupled behavior in the high-level radioactive waste disposal system based on the numerical simulation. DECOVALEX-2023 is the current phase consisting of 7 tasks, and Task C aims to model the THM coupled behavior in the disposal system based on the Full-scale Emplacement (FE) experiment at the Mont-Terri underground rock laboratory. This study performs the numerical simulation based on the OGS-FLAC developed for the current study. In the numerical model, we emplaced the heater with constant power horizontally based on the FE experiment and monitored the pressure development, temperature increase, and mechanical deformation at the specific monitoring points. We monitored the capillary pressure as the primary effect inducing the flow in the buffer system, and thermal stress and pressurization were dominant in the surrounding rocks' area. The results will also be compared and validated with the other participating groups and the experimental data further.