• Journal of Advanced Marine Engineering and Technology
• /
• 제32권1호
• /
• pp.137-146
• /
• 2008

Nd:YAG pulse laser welding of stainless steel plate was simulated to find welding condition by using commercial finite element code MARC. Due to geometric symmetry, a half model of AISI 304 stainless steel plate was considered and user subroutines were applied to boundary condition for the heat transfer. Material properties such as conductivity, specific heat, mass density and latent heat were given as a function of temperature. As results, Three dimensional heat source model for pulse laser beam conditions of butt welding has been designed by the comparison between the finite element analysis results and experimental data on AISI 304 stainless steel plate. Nd:YAG laser welding for AISI 304 stainless steel was successfully simulated and it should be useful to determine optimal welding condition.

• 한국기계가공학회지
• /
• 제2권3호
• /
• pp.76-83
• /
• 2003

Recently, the field of the engineering has been studied about optimum design continuously. Verified data by comparison with simulation and dynamic characteristic analysis enables the design of a machine tool to be modified easily and effectively concerning to the mode shape of the vibration. Especially, BC-500 Line Center has got some problems causing vibration which mainly come from Column and ATC part. So it is necessary to solve those problems by the two kinds of method such as changing structural design and reinforcing with ribs. In this paper, column and ATC part of BC-500 Line center are modified by an optimum design by the analysing method of FEM to avoid vibration. As a result, a more stable machine tool was designed by this simulation as optimum condition.

• 대한기계학회논문집A
• /
• 제23권11호
• /
• pp.2040-2049
• /
• 1999

The Rayleigh-Ritz method is used to investigate the natural frequencies and mode shapes of the ring stiffened cylindrical shells with a rectangular cutout. The cutout is located on the center of the shell. The Love's thin shell theory combined with the discrete stiffener theory is adopted to formulate the analytical model of the shell. The effect of stiffener eccentricity, number, and position on vibration characteristics of the shell is examined. Also the effect of cutout size is examined. By comparison with previously published analytical and new FEM results, it is shown that natural frequencies and mode shapes can be determined with adequate accuracy.

• 한국정밀공학회지
• /
• 제24권8호통권197호
• /
• pp.74-80
• /
• 2007

The distortion of printed pattern is frequently observed in gravure offset printing process, which can be a serious problem in printing process for printed electronics. The mechanism of pattern distortion is studied and the factors which affect the amount and shape of distortion are found using FEM. The amount and shape of distortion is influenced by material properties of the roller, thickness of roller, applied load, and so on. As the printing pressure increases and Possion ratio increases, the degree of the image distortion increases. And the increase of the thickness of rubber roller brings a large distortion of image, too. In some cases, the distortion of printed pattern can reach a few hundred micromillimeters. The comparison of the experiment result and the simulation result shows good agreement in their quantitative tendency.

• 한국소음진동공학회논문집
• /
• 제13권10호
• /
• pp.767-776
• /
• 2003

The theoretical method is developed to Investigate the nitration characteristics of the combined cylindrical shells with an annular plate joined to the shell at any arbitrary axial position. The structural coupling between shell and plate is simulated using two types of artificial springs a translational spring is introduced for translational coupling and a rotational spring is used for rotational coupling. The springs are continuously distributed along circumferential direction. Using the Rayleigh-Ritz method the natural frequencies and mode shapes of the combined shell with an annular plate examine. The effect of Inner-to-outer radius ratio, axial position of annular plate and length-to-radius ratio of shell on vibration characteristics of combined cylindrical shells is studied. The theoretical results are verified by comparison with FEM results.

• Steel and Composite Structures
• /
• 제5권1호
• /
• pp.1-15
• /
• 2005

Important characteristics of the previously proposed reduced stiffness method and a summery of its design curves for the buckling of the axially loaded sandwich cylindrical shells is presented. Comparison of the lower bound obtained with FEM analysis with that from the reduced stiffness analysis shows that the proposed reduced stiffness method can provide safe lower bounds for the buckling of geometrically imperfect, axially loaded sandwich cylindrical shells. One of the attractive features of the reduced stiffness elastic lower bound analysis is that it provides safe estimates of buckling loads that do not depend on the specification of the precise magnitude of the imperfection spectra. As a result, designers can readily apply this method without being worried about possible geometrical imperfections that might be generated during fabrication and construction of sandwich cylindrical shells.

• 전자공학회논문지D
• /
• 제34D권4호
• /
• pp.100-105
• /
• 1997

3-dimensional finite element mehtod (FEM) elecrical field analysis was performed to obtain electric fields on a field emission display (FED) tip in an array form. Because, unlike a single tip structure, there is no azimuthal symmetry for a tip aary, 3D analysis is necessary. To reduce memory requriement the simulatio was performed by applying the neumann boundary condition to the intermediate plane between tips to take the effect of the array on the electric field into account and corresponding current was calculated. To verify our algorithm, comparison between simulation resutls and experimental data from another paper was made and the difference was discussed.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제13권2호
• /
• pp.141-159
• /
• 2009

In this article, we consider a weighted CVT-based reduced-order modelling for Burgers equation. Brief review of the CVT (centroidal Voronoi tessellation) approaches to reduced-order bases are provided. In CVT-reduced order modelling, we start with a snapshot set just as is done in a POD (Proper Orthogonal Decomposition)-based setting. So far, the CVT was researched with uniform density ($\rho$(y) = 1) to determine the basis elements for the approximatin subspaces. Here, we shall investigate the technique of CVT with nonuniform density as a procedure to determine the basis elements for the approximating subspaces. Some numerical experiments including comparison of two CVT (CVT-uniform and CVT-nonuniform)-based algorithm with numerical results obtained from FEM(finite element method) and POD-based algorithm are reported.

• Tribology and Lubricants
• /
• 제20권6호
• /
• pp.314-321
• /
• 2004

Thermal distortion of non-contacting mechanical seals with inclined rubbing surfaces is affected by friction heat between seal ring and seal seat. The circulation fluid along the inclined rubbing surfaces maintains cooling friction heat and lubrication between the sealing surfaces of mechanical seal with an inclined surface. Mechanical seals with inclined sealing surfaces may be useful for reducing the frictional heating and power loss because of the introduction of cooling fluids to the sealing gap between seal ring and seal seat. From the FEM computed result shows that the thermal behavior and von Mises stress of sealing faces with an inclined angle 60 are much reduced in comparison of the conventional mechanical face seal with rectangular sealing surfaces.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 1997년도 춘계학술대회논문집
• /
• pp.125-129
• /
• 1997

Induction is a method of heating electrically conductive materials such as metals. It is commonly used in process heating prior to metalworking and in heating, welding, and melting. The number of industrial and consumer items which undergo induction heating during some stage of their production is very large and rapidly expanding. So a program to analyze the induction heating system was developed through the research. This thesis contains the procedure for developing the program. Both eddy current and temperature distribution are obtained through the analysis of the induction heating system. The program was developed to calculate 2-dimensional axisymmetric problem. The validity of the program is scrutinized through the comparison between the analytic solution and the numerical solution.