• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1794-1799
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• 2008

The effect of misfit on the indentation behaviour of silver coated copper multilayer was studied by molecular dynamics simulation. It was found that the misfit bands on interface formed by the mismatch of lattice structure between copper and silver in slip direction [110] and the dislocation band width depended on the mismatched lattice constants of materials. More dislocations were created and glided by indentation, which created a "four-wing flower" structure consisting of pile. up of dislocation at the interface. The size of "flower" depended on the thickness of silver layer. The critical thickness for "flower" was approximately 4nm above which the "flower" disappeared. As the result, deformation mechanisms such as dislocation pile-up, dislocation cross-slip and movement of misfit dislocation were revealed. Only silver atoms in the dislocation pile-up were involved in the creation of the "flower" while the dislocations in copper were glided in slip direction on interface.

• Steel and Composite Structures
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• v.26 no.1
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• pp.1-15
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• 2018

This study reported, the effect of random variation in system properties on bending response of single wall carbon nanotube reinforced composite (SWCNTRC) plates subjected to transverse uniform loading is examined. System parameters such as the SWCNT armchair, material properties, plate thickness and volume fraction of SWCNT are modelled as basic random variables. The basic formulation is based on higher order shear deformation theory to model the system behaviour of the SWCNTRC composite plate. A C0 finite element method in conjunction with the first order perturbation technique procedure developed earlier by the authors for the plate subjected to lateral loading is employed to obtain the mean and variance of the transverse deflection of the plate. The performance of the stochastic SWCNTRC composite model is demonstrated through a comparison of mean transverse central deflection with those results available in the literature and standard deviation of the deflection with an independent First Order perturbation Technique (FOPT), Second Order perturbation Technique (SOPT) and Monte Carlo simulation.

• Transactions of The Korea Fluid Power Systems Society
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• v.8 no.3
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• pp.21-26
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• 2011

Nonlinear seal friction in pneumatic cylinders can impede the performance of pneumatic systems designed for high precision positioning with favorable high speed actuation. The behaviour of an elastomeric piston seals in high speed pneumatic cylinders is analyzed by nonlinear finite element analysis using ABAQUS. The contact pressures, stress and strain distributions and frictional forces of the squeeze type piston seal are simulated with variation of the seal radial installed interference, the operating pressures, friction coefficients and piston rod velocities. The nonlinear finite element model of the squeeze type piston seal is used to predict deformation of a seal, friction force and contact pressure distributions.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.138-141
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• 2004

Finite element method is very effective method to simulate the forming processes with good prediction of the deformation behaviour. For the finite element modeling of sheet mental forming the accurate tool model is required. Due to the geometrical complexity of real-size part stamping tools it is hard to make FE model for real-size auto-body stamping parts. In this paper, it was focussed on the drawability factors on auto-body panel stamping by AUTOFORM with using tool planing alloy to reduce law price as well as high precision from Design Optimization of die. According to this study, the results of simulation will give engineers good information to access the Design Optimization of die.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.32 no.2
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• pp.164-176
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• 1996

The main intention of this paper is to develop and compare the algorithm based on finite element procedures for nonlinear transient dynamic analysis which has combined effects of material and geometric nonlinearities. Incremental equilibrium equations based on the principle of virtual work are derived by the finite element approach. For the elasto - plastic large deformation analysis of shells and the determination of the displacement-time configuration under time-varying loads, the explicit, implicit and combined explicit-implicit time integration algorithm is adopted. In the time structure is selected and the results are compared with each others. Isoparametric 8-noded quadrilateral curved elements are used for shell structure in the analysis and for geometrically nonlinear elastic behaviour, a total Lagrangian coordinate system was adopted. On the other hands, material nonlinearity is based on elasto-plastic models with Von-Mises yield criteria. Thus, the combined explicit-implicit time integration algorithm is benefit in general case of shell structure, which is the result of this paper.

• Smart Structures and Systems
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• v.15 no.5
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• pp.1271-1291
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• 2015

Helical structures made of superelastic shape memory alloys are widely used as interventional medical devices and active actuators. These structures generally undergo large deformation during expansion or actuation. Currently their behaviour is modelled numerically using the finite element method or obtained through experiments. Analytical tools are absent. In this paper, an analytical approach has been developed for analyzing the mechanical responses of such structures subjected to axial and torsional loads. The simulation results given by the analytical approach have been compared with both numerical and experimental data. Good agreements between the results indicate that the analysis is valid.

• Journal of Powder Materials
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• v.6 no.1
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• pp.96-102
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• 1999

The effect of Pb addition on microstructure and wear resistance was studied in rapidly solidified Al-20Si-5Fe-xPb(x=2, 4, 6 wt.%) alloys. The R/S Al-20Si-5Fe-xPb (x=2, 4, 6 wt.%) alloys showed a fine and homogeneous microstructure and an improved wear property compared with Al-20Si-5Fe alloy, while no significant change in UTS (Ultimate Tensile Strength) was shown. Contribution of the dispersoids on the wear property was discussed by showing the plastic deformation layers formed during wear track.

• Proceedings of the KSR Conference
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• 1998.05a
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• pp.385-392
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• 1998

Train crashes involve complex interaction between deformable bodies in multiple collisions. The purpose of this study is to suggest the effective analytical procedure using simple model for the crashworthiness of motorized trailer of high speed train. The simple model, with very short modeling time and reduced computation time was adopted to extract the global behaviour and to perform a pre-optimization of the considered structure. Firstly, various types of crash events are investigated and the conditions for numerical simulation are defined. The simple model, using the beam and non-linear spring element, and shell element model are used to evaluated energy absorption and deformation mechanism in analyses. And aluminum is applied to real model after verification with square tube analyses. Finally, loading path and energy absorption of main components are evaluated. The analyses are aimed to ensure the crashworthiness design of high speed train.

• 유공압시스템학회:학술대회논문집
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• 2010.06a
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• pp.99-104
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• 2010

Nonlinear seal friction in pneumatic cylinders can impede the performance of pneumatic systems designed for high precision positioning with favorable high speed actuation. The behaviour of an elastomeric piston seal in high speed pneumatic cylinders is analysed by nonlinear finite element analysis using ABAQUS. The contact pressures, stress and strain distributions and frictional forces of the piston seal are simulated with variation of interference fits, supply pressures, friction coefficients and piston rod velocities. The nonlinear finite element model of the piston seal is used to predict deformation of a seal, friction force and contact pressure distributions.

• Computational Structural Engineering
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• v.2 no.2
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• pp.53-62
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• 1989

In recent times, the subterranean caverns for storing crude oils and oil products are increasingly needed. The elasto-VIScoplastic DYNamic finite element analysis program(VISDYN) has been developed in order to investigate dynamic responses of the storage cavity. And validity of the program is studied through a numerical example. Mohr-Coulomb yield criterion is adopted and associated flow rule is assumed. Geometrically nonlinear behaviour is taken into account using a total Lagrangian formulation. In dynamic deformation reponses, the difference between the steady state displacements and the unsteady state ones by the static analysis can be neglected.