• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.6
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• pp.619-628
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• 2011

Human soft tissues, including muscles, ligaments, skin, and blood vessels, are an interesting subject because damage to them can be observed in everyday life. Besides the lack of available experimental data and the large deformation upon loading, the anisotropic and compressible nature of annulus fibrosus makes it more difficult to find a simple material model. A fiber-reinforced hyperelastic material model is used to determine the stress-strain curves upon uniaxial loading. The energy potential function for annulus fibrosus is composed of three different parts: matrix, fibers, and matrix-fiber interaction, which accounts for the angles between two families of fibers. In this paper, two different types of energy potential function for the matrix are considered, and are inserted into the fiber-reinforced model. The calculated results are compared with the Neo-Hookean model and experimental data, and reasonable agreement is observed overall.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.2
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• pp.83-90
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• 2010

The windshield wiper consists of 4 parts: a blade, an arm, a linkage and a motor. The wiper blade makes contact with the windshield and is designed to be operated normally at an angle of 30~50 degrees to the front glass. If the contact pressure between the wiper blade and windshield surface is too high, noise and wear of the rubber will result. On the other hand, if the contact pressure is too low, the performance will do badly, since foreign substances such as dust and stains will not be removed well. The pressure and friction of the wiper blade has a great influence on its effectiveness in cleaning the front window. This is due to the contact of the rubber with the window. This paper presents the dynamic analysis method to estimate the performance of the flat type blade of the wiper system. The blade has a nonlinear characteristic since the rubber is an incompressible hyper-elastic and visco-elastic material. Thus, Structural dynamic analysis using a complex contact model for the blade is performed to find the characteristics of the blade. The flexible multi-body dynamic model is verified by the comparison between test and analysis result. Also, the optimization using the central composite design table is performed.

• The Korean Journal of Rheology
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• v.11 no.1
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• pp.18-27
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• 1999

Predicting the deformation behaviors of sheets in thermoforming processes has been a daunting challenge due to the strong nonlinearities arising from very large deformations, mold-polymer contact condition and hyperelasticity constitutive equations. Nonlinear numerical analysis is always required to face this challenge especially for realistic processing conditions. In this study a 3-D algorithm and the membrane approximation are developed for thermoforming processes. The constitutive equation is expressed in terms of the 2nd Piola-Kirchhoff stress tensor and the Cauchy-Green deformation tensor. The 2-term Mooney-Rivlin model is used for the material model equation. The algorithm is established by the finite element formulation employing the total Lagrangian coordinate. The deformation behavior and the stress distribution results of 3-D algorithm with various point boundary conditions are compared to those of the membrane approximation algorithm. Also, the slip boundary condition and the no-slip boundary condition are applied for the systems that have molds. Finally, the effect of sheet temperatures on the final thickness distribution is investigated for the ABS material.