• Transactions of Materials Processing
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• v.9 no.3
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• pp.313-319
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• 2000

Finite element analysis is carried out for simulation of the multi-stage elliptic cup drawing process with the large aspect ratio. The analysis incorporates with shell elements for an elasto-plastic finite element method with the explicit time integration scheme. For the simulation, LS-DYNA3D is utilized for its wide capability of solving forming problems. The simulation result shows that the non-uniform drawing ratio at the elliptic cross section ad the small shoulder radius cause failure such as tearing and wrinkling. The result suggests the guideline to modify the tool shape for prevention of the failure during the drawing process.

• Structural Engineering and Mechanics
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• v.26 no.1
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• pp.31-42
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• 2007

The unsymmetric finite element formulation has been proposed recently to improve predictions from distorted finite elements. Studies have also shown that this special formulation using parametric functions for the test functions and metric functions for the trial functions works surprisingly well because the former satisfy the continuity conditions while the latter ensure that the stress representation during finite element computation can retrieve in a best-fit manner, the actual variation of stress in the metric space. However, a question that remained was whether the unsymmetric formulation was variationally correct. Here we determine that it is not, using the simplest possible element to amplify the principles.

• Journal of Electrical Engineering and Technology
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• v.6 no.3
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• pp.342-349
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• 2011

This paper presents a study on rotor asymmetry caused by broken bars and its effects on the stator current of an induction machine under an unbalanced supply voltage. The simulation of the induction machine is based on the finite element method. In the early stage of diagnosis, we show new sidebands specific to the partial rupture of the rotor bar. Experimental tests corroborate with the simulation results.

• Transactions of Materials Processing
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• v.9 no.2
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• pp.159-164
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• 2000

In this paper, a computer simulation technique for the forging process having a floating die is presented. The penalty rigid-plastic finite element method is employed together with an iteratively force-balancing method, in which the convergence is achieved when the floating die part is in force equilibrium within the user-specified tolerance. The force balance is controled by adjusting the velocity of the floating die in an automatic manner. An application example of a three-stage cold forging process is given.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.10a
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• pp.205-208
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• 2001

A lumped electrical circuit is an approximate representation of the field within a curtain frequency range. The finite element modelling is a synonym of the equivalent circuit. The electric conduction field and electric potential wave field have been modelled by an admittance network and an LC low-pass filter network. Here in the present paper, the equivalent magnetic circuit representation is created for a magnetostatic field by the finite element modelling in two dimension.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1565-1568
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• 2003

The backward extrusion process is one of the commonly used metal forming processes. In this paper. a battery case which has the rectangular section, is analyzed using a 3D metal forming package(MSC.Superforge). This pacakge uses the finite volume analysis method. It is shown that the MSC.Superforge package using finite volume method provides result very close to those obtained from a finite element analysis package(MSC.Superform). However, the simulation time using the finite volume method was almost 10 % of the simulation time consumed by the other package using finite element method. Moreover, the finite volume method used in MSC.Superforge can eliminate the remeshing problems that make the simulating a metal forming process with severe deformation, such as the extrusion process, so difficult.

• Transactions of Materials Processing
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• v.16 no.3 s.93
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• pp.187-192
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• 2007

The finite volume method for forging simulation is examined to reveal its possibility as well as its problem in this paper. For this study, the finite volume method based MSC/SuperForge and the finite element method based AFDEX are employed. The simulated results of the homogeneous compression obtained by the two softwares are compared to indicate the problems of the finite volume method while several application examples are given to show the possibility of the finite volume method fur simulation of complex hot forging processes. It is shown that the finite volume method can not predict the exact solution of the homogeneous compression especially in terms of forming load and deformed shape but that it is helpful to simulate very complex forging processes which can hardly be simulated by the conventional finite element method.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.153-161
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• 2002

This paper develops a finite element model for crashworthiness analysis ova small-sized bus. The full vehicle finite element model is composed of 31,982 shell elements,599 beam elements,42 bar elements, and 34,204 nodes. The model uses four material models (such as elastic, elastic-plastic(steel), rigid. and elastic-plastic (rubber) material model) of PAM-CRASH. The model uses four contact types to define sliding interfaces in ten areas. A frontal crash test using an actual vehicle with 30mph velocity to a rigid barrier is carried out. Vehicle pulses at lower part of left and right b-pillar are measured, and deformed shapes of frame and driver seat's lower left area are photographed. A frontal crash simulation using the developed full vehicle finite element model is performed with PAM-CRASH installed in super computer SP2. The simulation is performed with the same conditions as the test. The measured vehicle pulses and photographed deformed shapes from the test are compared to ones from the simulation to validate the reliability of the developed model.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.384-388
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• 2005

The purpose of this paper is to develop web-based simulation system which can be used anytime, anywhere without expensive hardware and software. In this paper, a web-based simulation system was developed by utilizing finite element analysis and client/server system using visual C++ and ASP. The client/server system consist of two modules, post-processor, management system module. The input data for FEM calculation is transferred to the management system. After that, the result from the simulation can be visualized through the post-processor module. By using this system, small industries and individuals can considerably save the time and expense.

• Transactions of Materials Processing
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• v.30 no.4
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• pp.186-194
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• 2021

Finite element simulation is a widely applied method for practical purpose in various metal forming process. However, in the simulation of elasto-plastic behavior of porous material or in crystal plasticity coupled multi-scale simulation, it requires much calculation time, which is a limitation in its application in practical situations. A machine learning model that directly outputs the constitutive equation without iterative calculations would greatly reduce the calculation time of the simulation. In this study, we examined the possibility of artificial intelligence based constitutive equation with the input of existing state variables and current velocity filed. To introduce the methodology, we described the process of obtaining the training data, machine learning process and the coupling of machine learning model with commercial software DEFROM^TM, as a preliminary study, via rigid plastic finite element simulation.