• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.11
• /
• pp.150-157
• /
• 2003

In this paper, the large deformation of hollow silicon rubber gasket is treated. The frictional contact occurs between groove and the outer part of hollow gasket, and the frictional self-contact exists in the inner parts of hollow gasket. The silicon rubber has the nonlinear elastic behavior and its material property is approximately incompressible. Hence, the stress analysis requires an existence of a strain energy function, which is usually defined in terms of invariants or stretch ratio such as generalized Mooney-Rivlin and Ogden model. Considering large compressive deformation and friction, Mooney-Rivlin 3rd model and Coulomb's friction model are assumed. The numerical analysis is obtained by the commercial finite element program MARC. But, due to large deformation, the elements degenerate in the inner parts of hollow gasket. This means that the analysis of subsequent increments is carried out with a very poor mesh. In order to continue the analysis with a sufficient accuracy, it is necessary to use new finite element modeling by remesh. Experiments are also performed to show the validity of present method. As a conclusion, numerical results by this research have good agreements with experiments.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2010.03a
• /
• pp.1194-1199
• /
• 2010

Systematic finite element analyses on consolidation were performed with various drainage conditions. Numerical analyses were performed using SAGE CRISP2D, a commercial numerical analysis program for the conventional geotechnical engineering practice. For the input properties of the numerical analyses, incremental loading oedometer tests were performed on reconstituted kaolinite samples. Numerical analyses were performed with various drainage conditions such as vertical, radially inward and outward drainage conditions. For the case of radially inward drainage conditions, a series of numerical analyses were performed with varying the diameter of vertical drains. As a result, the lateral deformation and void ratio variation occurred during consolidation for the radially inward or outward drainage conditions. And the variations of the lateral deformation and void ratio did not fully disappear even after the completion of the consolidation and induced the spatial variations of the soil properties. Keywords : finite element analysis of consolidation, various drainage conditions, lateral deformation, spatial variation of soil properties.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.11
• /
• pp.1730-1736
• /
• 2001

A finite element analysis for a rotating cantilever beam is presented in this study. Based on a dynamic modeling method using the stretch deformation instead of the conventional axial deformation, three linear partial differential equations are (derived from Hamilton's principle. Two of the linear differential equations show the coupling effect between stretch and chordwise deformations. The other equation is an uncoupled one for the flapwise deformation. From these partial differential equations and the associated boundary conditions, two weak forms are derived: one is for the chordwise motion and the other is fur the flptwise motion. The weak farms are spatially discretized with newly defined two-node beam elements. With the discretized equations or the matrix-vector equations, the behaviors of the natural frequencies are investigated for the variation of the rotating speed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.6 no.1
• /
• pp.83-86
• /
• 2005

This study is predicted tool deformation by cutting forces and chip-tool interface temperature in machining process. Modeling of tool is made using 3D CAD software, finite element method is performed by cutting forces and temperature. Cutting forces and temperature used load conditions are predicted using the cutting force model based on machining theory. Experimental milling tests have been conducted to verify the cutting force model. Finally, this study is predicted cutting force components and temperature using cutting conditions, material property, tool geometry without experiment and tool deformation is predicted by cutting forces and temperature in machining process.

• International Journal of Aeronautical and Space Sciences
• /
• v.14 no.4
• /
• pp.310-323
• /
• 2013

In this paper, the aeroelastic static response of flexible wings with arbitrary cross-section geometry via a coupled CUF-XFLR5 approach is presented. Refined structural one-dimensional (1D) models, with a variable order of expansion for the displacement field, are developed on the basis of the Carrera Unified Formulation (CUF), taking into account cross-sectional deformability. A three-dimensional (3D) Panel Method is employed for the aerodynamic analysis, providing more accuracy with respect to the Vortex Lattice Method (VLM). A straight wing with an airfoil cross-section is modeled as a clamped beam, by means of the finite element method (FEM). Numerical results present the variation of wing aerodynamic parameters, and the equilibrium aeroelastic response is evaluated in terms of displacements and in-plane cross-section deformation. Aeroelastic coupled analyses are based on an iterative procedure, as well as a linear coupling approach for different free stream velocities. A convergent trend of displacements and aerodynamic coefficients is achieved as the structural model accuracy increases. Comparisons with 3D finite element solutions prove that an accurate description of the in-plane cross-section deformation is provided by the proposed 1D CUF model, through a significant reduction in computational cost.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.13 no.4
• /
• pp.680-688
• /
• 1989

A numerical method for analyzing non-isothermal plastic deformation of sheet metals has been developed and sheet tensile tests have been analyzed using a two-dimensional finite element formulation. A modified Bishop`s method is used to solve the thermoplasticity problem in decoupled form at each time step. The accuracy of the analysis is confirmed by comparison with experimental data. The uniform elongation is found is drop by 0.1 to 2.7% at moderate strain rates, while total elongation decreases upto 6.0% during tensile testing in air compared to the isothermal case. The effect of deformation heating, becomes more pronounced as necking develops and at higher testing speed.

• Transactions of Materials Processing
• /
• v.5 no.2
• /
• pp.122-129
• /
• 1996

The main objective of the study is to offer some basic information in relation to optimal shape and dimensions of the rotating band through the development of three-dimensional finite element method for metal forming analysis of the rotating band whose primary function is to impart spin to the projectile. The three-dimensional metal forming analysis of the rotating band has perfor-med by using recurrent boundary conditions. Such design factors as the outside diameter the total length and the profile of the rotating band must be considered carefully in order to design an optimal rotating band. Above design factors can be determined from such available analysis results as the deformed shape and the deformation load. of the rotating band and the normal pressure of the rotating band on a projectile shell. The remeshings are needed to carry out plastic deformation analysis with severe deformation through which the complete process analysis gets possible. The results can be utilized effectively in determining the optimal shape and size of the rotating band.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.9
• /
• pp.117-126
• /
• 1998

For investigating rubber pad sheet metal forming process, the rubber pad deformation characteristics as well as the contact problem of rubber pad-sheet metal has been analyzed. In this paper, the behavior of the rubber deformation is represented by hyper-elastic constitutive relations based on a generalized Mooney-Rivlin model. Finite element procedures for the two-dimensional responses, employing total Lagrangian formulations are implemented in an implicit form. The volumetric incompressibility condition of the rubber deformation is included in the formulation by using penalty method. The sheet metal is characterized by elasto-plastic material with strain hardening effect and analyzed by a commercial code. The contact procedure and interface program between rubber pad and sheet metal are implemented. Inflation experiment of circular rubber pad identifies the behaviour of the rubber pad deformation during the process. The various form dies and scaled down apparatus of the rubber-pad forming process are fabricated for simulating realistic forming process. The obtaining experimental data and FEM solutions were compared. The numerical solutions illustrate fair agreement with experimental results. The forming pressure distribution according to the dimensions of sheet metal and rubber pads, various rubber models and rubber material are also compared and discussed.

• Korean Journal of Metals and Materials
• /
• v.48 no.7
• /
• pp.598-604
• /
• 2010

Tensile tests are widely used for evaluating mechanical properties of materials including flow curves as well as Young's modulus, yield strength, tensile strength, and yield point elongation. This research aims at analyzing the plastic flow behavior of high strength steels for automotive bodies using the finite element method in conjunction with the viscoplastic model considering the yield point elongation phenomenon. The plastic flow behavior of the high strength steel was successfully predicted, by considering an operating deformation mechanism, in terms of normalization dislocation density, and strain hardening and accumulative damage of high strength steel using the modified constitutive model. In addition, the finite element method is employed to track the properties of the high strength steel pertaining to the deformation histories in a skin pass mill process.

• Korean Journal of Metals and Materials
• /
• v.46 no.3
• /
• pp.144-149
• /
• 2008

Equal channel angular pressing (ECAP) has been studied intensively over the decade as a typical top-down process to produce ultrafine/nano structured materials. ECAP has successfully been applied for a processing method of severe plastic deformation to achieve grain refinement of magnesium and to enhance its low ductility. However, difficult-to-work materials such as magnesium and titanium alloys were susceptible to shear localization during ECAP, leading to surface cracking. The front pressure, developed by Australian researchers, can impose hydrostatic pressure and increase the strain level in the material, preventing the surface defect on workpiece. In the present study, we investigated the deformation and fracture behavior of pure magnesium using experimental and numerical methods. The finite element method with different ductile fracture models was employed to simulate plastic deformation and fracture behavior of the workpiece.