• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.148-151
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• 2005

Roughness of a road is an important parameter which not only indicates vehicle's vibration and noise, but it is also related to the contact force of the tire which is induced by tire's deformation and vibration. Since tire noise indeed comes from this deformation and vibration, the estimation of the force is the key factor fur the reduction of tire noise. Because of the difficulty of directly measuring the contact force, the indirect estimation is enforced from the vibration signature measured on the tire support. This study suggests the "inverse filtering" technique well known in modern digital signal processing, so as to reform the tire contact force from monitored vibration signals.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1215-1220
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• 2008

The aim of this paper is to perform a finite element analysis that will have the ability to predict the seal performance characteristics, such as deformation, contact load and friction and also is to provide a means of potential seal designs, which can reduce the time and cost of designing the performance of the seal. The material property tests of elastomer seal are performed to obtain the hyperelastic properties and The Mooney-Rivlin constants are determined from these test results. A 2D modelling of the seal cross section is performed to simulate the contact behavior between the seal on the piston and the cylinder bore under operation conditions. The deformation behavior, contact load and friction of an elastomer seal is analyzed by a finite element method which performs three analytic phases of interference fit, the variations of pneumatic pressure and piston movement under the operational conditions.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.323-330
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• 1999

The conventional analysis for the numerical computation of fluid film thickness with elastic deformation of contact region. is performed by Newton-Rephson method for its 18st convergence characteristics. However, both high load and relatively low sliding velocity frequently make it impossible for Newton-Rahpson method to get both converged and stable solutions. In particular, this method cannot provide converged Solution under the condition of high load above 1.0 GPa which frequently occurs in line contact of EHL problem. Multigird multi-level method for the solver of non-linear partial differential equation including solid deformation is preferred to Newton-Rshpson method for better convergence and stability and is applied to line contact EHL behavior in this study.

• Proceedings of the KSR Conference
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• 1998.05a
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• pp.315-322
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• 1998

A two dimensional elasto-plastic finite element program taking into account contact between crack surfaces if developed in order to analyze subsurface cracking in rolling contact. But the friction between upper and lower surface of the crack is not considered. Under the assumptions of small deformation and small displacement, the incremental theory of plasticity is used to describe plastic deformation. J-integral is computed as the applied Hertzian load slides over the surface with friction. J-integral is correlated with wear rate of the rail. The propagation rate of the right tip of the surface crack is fast by 45% than that of the left side.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.1103-1104
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.499-502
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• 2005

A process map has been developed, which can identify the process conditions for weak mechanical bonding at the contact surface during the direct extrusion of a Cu-Ti bimetal bar. Bonding mechanism between Cu and Ti was assumed as a cold pressure welding. Then, the plastic deformation at the contact zone causes mechanical bonding and a new bonding criterion for pressure welding was developed as a function of the principal stretch ratio and normal pressure at the contact surface by analyzing micro local extrusion at the contact zone. Finite element analyses for extrusion of Cu-Ti bimetal bars were performed for various process conditions. The deformation history at the contact surface was traced and the proposed new bonding criterion was applied to predict whether the mechanical bonding at the Cu-Ti contact surface happens. Finally, a process map for the extrusion of Cu-Ti bimetal bar is suggested.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1129-1137
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• 1990

Based on the formulation which incorporates large deformation and anisotropy, an elastic-plastic finite element code is developed with membrane element to include the contact treatment. For the analysis of the general sheet metal forming process with contact condition, the treatment of contact is considered by employing the successive skew coordinate system. Three kinds of sheet metal forming processes with contact conditions are analyzed; stretching of a square diaphragm with a hemispherical punch, deep drawing of a circular cup and deep drawing of a square cup. Then the computational results are compared with the experiment. The computed loads and the distribution of the thickness strain are in good agreement with the experiment for all cases. However, the computational results of the thickness strain show the effect of bending can not be ignored in the deep drawing process whereas the effect of bending is negligible in stretching.

• Nuclear Engineering and Technology
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• v.56 no.8
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• pp.3450-3462
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• 2024

This paper presents a computational framework for drop time assessment of a control element assembly (CEA) under fuel assembly (FA) deformations. The proposed framework consists of three key components: 1) finite element modeling of CEA, 2) fluid-structure interaction to compute drag force, and 3) modeling of frictional contact between CEA and FA. Specially, to accommodate the large motion of CEA, beam elements based on absolute nodal coordinate formulation (ANCF) are adopted. The continuity equation is utilized to calculate the drag force, considering flow changes in the cross-sectional area during the CEA drop. Lastly, beam-inside-beam frictional contact model is employed to capture practical contact conditions between CEA and FA. The proposed framework is validated through experiments under two scenarios: free falls of CEA within FA, encompassing undeformed and deformed scenarios. The experimental validation of the framework demonstrated that the drop time of CEA can be accurately predicted under the complex coupling effects of fluid and frictional contact. The drop times of the S-shaped deformation case is longer than those of the C-shaped deformation case, affirming the time delay due to frictional force. The validation confirms the potential applicability to access the safety and reliability of nuclear power plants under extreme conditions.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.767-774
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• 2007

Even though a constant repeated load is applied, plastic deformation may cumulate. This kind of behavior is called ratcheting. Ratcheting may lead to cracks and finally to failure of the rail. Usually ratcheting occurs on high rails in curves. Ratcheting is influenced by residual stresses, wheel-rail contact stresses, thermal stresses due to wheel/rail rolling contact, shear strength of the rail, strain hardening behavior, etc. In this study, contact stresses and thermal stresses are examined. It is found their value is considerable compared to the maximum contact pressure.

• Journal of the Korean Institute of Gas
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• v.16 no.5
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• pp.47-51
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• 2012

In this study, the deformation behavior stability of sealing rings with three different cross sectional areas has been presented using a FEM technique. To investigate the deformation behavior stability, the initial compression rate of 25% has been applied to the sealing ring, which is molded with a nitrile butadiene rubber. The maximum strain, maximum stress, and maximum contact normal stress have been analyzed for the working fluid pressure of $25kgf/cm^2$. The FEM results show that the maximum strain of a hollow o-ring and a hollow rectangular ring with a hollow space in the center of a sealing ring is higher than that of a conventional o-ring, but the maximum stress and the maximum contact normal stress are low. In these results, the sealing rings with a hollow space in the center of the cross sectional area is recommended to increase an extended endurance stability of sealing rings. But, the solid sealing ring is designed to guarantee the sealing safety of a contact sealing ring.