• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1545-1548
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• 2003

In rigid-plastic finite element method, there is a heavy computation time and convergence problem. In this study. static-explicit rigid-plastic finite element method will be introduced. This method is the way that restrict the convergence interval. In result, convergence problem and computation time due to large non-linearity in the existing numerical analysis method were no longer a critical problem. Also, we investigated the effect of punch stroke and the strain increment this method. It is expected that various results from the numerical analysis will give very useful information for the design of tools in sheet metal forming process.

• Structural Engineering and Mechanics
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• v.29 no.6
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• pp.709-729
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• 2008

This paper describes a three-dimensional dynamic finite element analysis of two/multiple shots impacting on a metallic component. The model is validated against a published numerical study. An extensive parametric study is conducted to investigate the effect of shot impacting with overlap on the resulting residual stress profile within the component, including time interval between shot impacts, separation distance between the impacting points, and impacting velocity of successive shots. Several meaningful conclusions can be drawn regarding the effect of shot impacting with overlap.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.3
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• pp.39-45
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• 2004

In rigid-plastic finite element method, there is a heavy computation time and convergence problem. In this study, static-explicit rigid-plastic finite element method will be introduced. This method is the way that restrict the convergence interval. In result, convergence problem and computation time due to large non-linearity in the existing numerical analysis method were no longer a critical problem. It is expected that various results from the numerical analysis will give very useful information for the design of tools in sheet metal forming process.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.2
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• pp.91-97
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• 2003

In rigid-plastic finite element method, there is a heavy computation time and convergence problem. In this study, revised rigid-plastic finite element method Will be introduced. This method is the way that restrict the convergence interval. In result, convergence problem and computation time due to large non-linearity in the existing numerical analysis method were no longer a critical problem. It is expected that various results from the numerical analysis will give very useful information for the design of tools in sheet metal forming process.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.4
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• pp.5-14
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• 2002

This paper addresses the challenges of dealing with uncertainties based on interval analysis. An interval approach is proposed on the basis of Boundary Selection Method (BSM) for treating systems of linear interval equations in the presence of columnwise dependencies. An iterative procedure is developed for the problem solving where uncertainties are characterized in the form of interval quantities. An applied example is used to illustrate effectiveness and usefulness of the proposed approach. This new method can be applied for such circumstances that involve finite element analysis of structures, inverse dynamic analysis of mechanisms, and worst case design studies in the presence of the uncertainties.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.627-628
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• 2007

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.3
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• pp.555-564
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• 1994

This study has been made to investigate the stress distribution around defects and inclusions that behave as stress concentrators. The stress distribution and interation effects around defects and inclusions was analyzed using Finite Element Method. The results are as follows;(1) Maximum stress point in case of $E_I/E_M>1$($E_I$:elasticity modulus forthe inclusion, $E_M$/:elasticity modulus for the base material)is the vertical point with respect to force direction and in case of $E_I/E_M<1$ it is the parallel point along the hole edge. (2) Interaction effects of ${\sigma}_y$ for the inclusion side is larger than the defect side when the interval between inclusion and defect is near. (3) stress interation effects is large if the difference of ${\sigma}_y$ is small and it is small if the difference of ${\sigma}_y$ is large for the case that the interval between inclusion and defect whose size and property are different is near.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.5
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• pp.81-87
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• 2015

In this paper, the finite element method was used for the flow and strength analysis of aluminum alloy under friction stir welding. The simulations were carried out using Sysweld s/w, and the modeling of the sheet was executed using Unigraphics NX6 s/w. The welding variables for the analysis were the shoulder diameter, rotating speed, and welding speed of the tool. Additionally, a three-way factorial design method was applied to confirm the effect of the welding variables on the flow and strength analysis with variance analysis. From these results, the rotating speed had the greatest influence on the maximum temperature, and the maximum temperature was $578.84{\pm}12.72$ at a confidence interval of 99%. The greater the rotating speed and shoulder diameter, the greater the difference between maximum and minimum temperature. Furthermore, the shoulder diameter had the largest influence on von Mises stress, and the von Mises stress was $184.54{\pm}12.62$ at a confidence interval of 99%. In addition to the increased shoulder diameter, welding speed, and rotating speed of the tool increased the von Mises stress.

• Journal of the Korean Society for Railway
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• v.8 no.1
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• pp.41-50
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• 2005

Steel -Concrete Composite two girder railway bridges applying high performance steel with extra thick plate have economic and aesthetic advantages due to the simplification of manufacturing and construction process. However, steel bridges are seldom adopted in domestic railway bridge, since steel bridges are not efficient as R.C bridges considering dynamic characteristics and noise, etc. While highway bridges do not have lower horizontal bracing and larger interval of diaphragm cross beam, railway bridges install lower horizontal bracings to control the torsion due to heavy eccentrical line load. Accurate finite element analysis were performed with the parameters of existence of bracing and bracing shape, with the cross beam interval and stiffness, etc. To find out the effects of secondary members such as horizontal bracings and diaphragms, static md dynamic analysis have been performed by using finite element method. In this study, few member plate-girder bridges are analyzed with variable span lengths to examine the dynamic behavior and limits of damping. And though lateral bracings are members against torsion, but lateral bracing's absence is no big problem. Time history analysis using mode superposition method makes proof of this result.

• Agricultural and Biosystems Engineering
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• v.7 no.1
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• pp.1-7
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• 2006

A need exists to monitor and control the localized high temperatures often experienced in solar grain dryers, which result in grain cracking, reduced germination and loss of cooking quality. A verified finite element model would be a useful to monitor and control the drying process. This study examined the feasibility of the finite element method (FEM) to predict temperature distribution in solar grain dryers. To achieve this, an indirect solar grain dryer system was developed. It consisted of a solar collector, plenum and drying chambers, and an electric fan. The system was used to acquire the necessary input and output data for the finite element model. The input data comprised ambient and plenum chamber temperatures, prevailing wind velocities, thermal conductivities of air, grain and dryer wall, and node locations in the xy-plane. The outputs were temperature at the different nodes, and these were compared with measured values. The ${\pm}5%$ residual error interval employed in the analysis yielded an overall prediction performance level of 83.3% for temperature distribution in the dryer. Satisfactory prediction levels were also attained for the lateral (61.5-96.2%) and vertical (73.1-92.3%) directions of grain drying. These results demonstrate that it is feasible to use a two-dimensional (2-D) finite element model to predict temperature distribution in a grain solar dryer. Consequently, the method offers considerable advantage over experimental approaches as it reduces time requirements and the need for expensive measuring equipment, and it also yields relatively accurate results.