• Journal of the Microelectronics and Packaging Society
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• v.27 no.1
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• pp.67-73
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• 2020

In this paper, we used FEM technique to perform warpage and von Mises stress analysis on PCB according to the cavity structures of embedded PCB for FCCSP and the types of prepreg material. One-half substrate model and static analysis are applied to the FEM. According to the analysis results of the warpage, as the gap between the cavity and the chip increased, warpage increased and warpage increased when prepreg material with higher modularity and thermal expansion coefficient was applied. The analysis results of the von Mises stress show that the effect of the gap between the cavity and the chip varies depending on prepreg material. In other words, when material whose coefficient of thermal expansion is significantly higher than that of core material, the stress increased as the gap between the cavity and the chip increased. When the prepreg with the coefficient of thermal expansion lower than the core material is applied, the result of stress is opposite. These results indicate that from a reliability perspective, there is a correlation between the structure of the cavity where embedded chips are loaded and prepreg material.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.301-304
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• 2003

Nowadays, hydration heat analysis using FEM is common in thermal crack control of concrete structure. Many kinds of general FEM programs for hydration heat analysis are used in practice. But there are some problems in this using. In this study hydration heat analysis of wall according to placement length are performed. In this results we could get two conclusions. First, general structures like wall having general geometry and construction condition have similar behavior. So it is not necessary to analysis thermal crack in every case. Second, the results of 2D analysis is possible to be applied instead of those of 3D analysis because the results of 2D analysis is similar to 3D analysis in long wall having about 15~18m or over length at 3m height.

• Journal of Korea Foundry Society
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• v.25 no.5
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• pp.209-215
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• 2005

The design of the Metal mold casting should consider several variables such as the material properties and shape of the mold. In particular, the thermal stress generated by the thermal expansion and contraction depending on the thermal gradient of the mold causes partial plastic deformation on the mold, which causes damage or fracture of the cast. Consequently, the thermal deformation along with thermal stress leads to thermal deformation of the cast itself. In this study, the temperature analysis of the cast and mold is simulated by FDM to control the thermal deformation and stress as a result of the thermal gradient of mold. Using the results from FDM simulation, the thermal deformation and stress are analyzed by FEM and, the optimal mold design with minimum thermal deformation of the cast is suggested.

• Korean Journal of Metals and Materials
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• v.49 no.6
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• pp.468-473
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• 2011

Determining the residual stress during casting processes is important for evaluating the mechanical properties and strength of materials and to optimize manufacturing conditions. In this study, we propose a field data interface procedure between FDM and FEM in a 3-dimensional space for analyzing the casting process and structural analysis. The casting process was analyzed using FDM and the data of the temperature distribution were converted into a format suitable for FEM analysis to calculate the thermal stress and safety factor by tightening force. The results of the coupled analysis between FDM and FEM showed that casting residual stress is an important factor in predicting life time and evaluating durability.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.363-364
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.265-266
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• 2009

• Structural Engineering and Mechanics
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• v.85 no.4
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• pp.445-459
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• 2023

The current investigation is the first endeavor to apply the full layerwise finite element method (FEM) in free vibration analysis of functionally graded (FG) composite plates reinforced with graphene nanoplatelets (GPLs) in thermal environment. Unlike the equivalent single-layer (ESL) theories, the layerwise FEM focuses on all three-dimensional (3D) effects. The GPLs weight fraction is presumed invariable in each layer but varies through the plate thickness in a layerwise model. The modified Halpin-Tsai model is employed to acquire the effective Young's modulus. The rule of mixtures is applied to specify the effective Poisson's ratio and mass density. First, the current method is validated by comparing the numerical results with those stated in the available works. Next, a thorough numerical study is performed to examine the influence of various factors involving the pattern of distribution, weight fraction, geometry, and size of GPLs, together with the thickness-to-span ratio, thermal environment, and boundary conditions of the plate, on its free vibration behaviors. Numerical results demonstrate that employing a small percentage of GPL as reinforcement considerably grows the natural frequencies of the pure epoxy. Also, distributing more square-shaped GPLs, involving a smaller amount of graphene layers, and vicinity to the upper and lower surfaces make it the most efficient method to enhance the free vibration behaviors of the plate.

• International Journal of Automotive Technology
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• v.1 no.2
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• pp.79-87
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• 2000

Analytical approach was followed in this work under both the steady state and transient operating conditions to find optimum boundary conditions, where the optically accessible quartz engine can run safely without breaking. Temperature and stress distribution was predicted by FEM analysis. In order to validate thermal boundary condition, model reliability and constraint, outside cylinder temperature was measured and previous study was also followed up numerically. To reduce thermal stress level, three types of outside cooling (natural, moderate forced and intensive forced convection) were considered. Effects of clamping force and combustion pressure were conducted to investigate mechanical stress level. Cylinder thickness, was changed to fine the optimum cylinder thickness. The versatile results achieved from this work can be basic indication, which is capable of causing a sudden quartz cylinder breaking during fired operation.

• Journal of Welding and Joining
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• v.25 no.2
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• pp.70-75
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• 2007

Simplified mathematical formulas are presented to predict deformations during the plate forming process when the heating parameters are given. To obtain the formulas, firstly, the thermal analysis for steel plate is performed, and the thermo-mechanical analysis is followed with actual heating conditions. The analyses have been carried out by the commercial software MARC, which is programmed based on the FEM. Secondary, the results of the mechanical analysis are synthesized with their variables for a statistical approach, which results in simplified formulas. The results of the analysis are well compared with those of experimental measurements.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.95-101
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• 2001

Steel bridges, which have been damaged by load and corrosion, need repair or strengthening. In general, before the repair welding procedure, cutting procedure carry out. Therefore, the investigating of the behavior of stress generated by cutting is so important for safety of structure. Residual stress produced by gas cutting was analyzed using 2D and 3D thermal elasto-plastic FEM. According to the results, the magnitude of temperature was analyzed by 2D-FEM is smaller than that was analyzed using the 3D-FEM program at the start and end edge of flange. And the magnitude and distribution of residual stress of perpendicular to the cutting line was analyzed by the 2D-FEM program was similar to that was analyzed by the 3B-FEM program. Therefore, it is possible to predict of cutting stress by 2D and 3D FEM.