• Interaction and multiscale mechanics
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• v.6 no.2
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• pp.137-156
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• 2013

In this paper, a meshfree shell adaptive procedure is developed for the applications in the sheet metal forming simulation. The meshfree shell formulation is based on the first-order shear deformable shell theory and utilizes the degenerated continuum and updated Lagrangian approach for the nonlinear analysis. For the sheet metal forming simulation, an h-type adaptivity based on the meshfree background cells is considered and a geometric error indicator is adopted. The enriched nodes in adaptivity are added to the centroids of the adaptive cells and their shape functions are computed using a first-order generalized meshfree (GMF) convex approximation. The GMF convex approximation provides a smooth and non-negative shape function that vanishes at the boundary, thus the enriched nodes have no influence outside the adapted cells and only the shape functions within the adaptive cells need to be re-computed. Based on this concept, a multi-level refinement procedure is developed which does not require the constraint equations to enforce the compatibility. With this approach the adaptive solution maintains the order of meshfree approximation with least computational cost. Two numerical examples are presented to demonstrate the performance of the proposed method in the adaptive shell analysis.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.122-125
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• 2005

The AutoForm previously used the membrane element and it accomplished sheet metal forming analysis. The membrane analysis has been widely applied to various sheet metal forming processes because of its saving time effectiveness. However, it's well known that the membrane analysis can not provides correct information for the processes which considerable bending effects. From this time research it tried to compare the formation analysis result which uses the shell element which is applied newly in the AutoForm and actual products. The shell element is compromise method between continuum analysis and membrane analysis. The Finite element method by using shell element is the most economical numerical method. From analysis results, FEA by using shell element can estimate accurately the problems happened in actual auto-body panel.

• Journal of the Korean Ceramic Society
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• v.46 no.1
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• pp.94-101
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• 2009

The physical properties of artificial aggregates made from clay and inorganic wastes with poor plasticity depends largely on forming method. The artificial aggregates composing of coal fly ash, stone sludge and clay were fabricated using 4 different forming methods and those physical properties were comparatively analyzed. The surface of aggregates made through the extrusion forming process was dense and smooth but was rough for the aggregates obtained by crushing a tile-shaped green body. The aggregates made by pelletizing process had a weak green strength and bumpy surface. The shell generated at surface during a high temperature sintering process induced the most aggregates to be bloated due to a dense shell. But the aggregates made through pelletizing process with dense surface layer showed no significant change in bulk density with sintering temperatures. The water absorption of aggregates decreased with sintering temperature, and that of pelletized specimen was standing $1.8{\sim}2.2$ times higher than that of made by other forming methods. It is concluded that the aggregates having various properties could be fabricated from one batch by using different forming methods.

• Journal of Korea Foundry Society
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• v.18 no.5
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• pp.481-487
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• 1998

Shell sand is widely used to make a complex shape castings due to its good collapsibility. When molten metal is poured into the mold, various gases are generated by the thermal decomposition of binder in the shell core. Casting defects such as blow hole and blister come from these gases. If it is possible to predict the evolution of gas quantitatively, it may provide effective solutions for minimizing the casting defects. To examine the gas evolution by shell core quantitatively, casting experiment and calculation were carried out. Gas pressure and gas volume evolved by shell core were measured in the experiment, and temperature distribution in the shell core was obtained by heat transfer analysis. From the result above, prediction on the gas volume evolved during pouring was tried. As forming pressure of the shell core increased and forming temperature decreased, the gas evolution increased. There was a close relationship between the calculated gas volume evolved and the measured one.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.8
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• pp.635-640
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• 2016

The shell body is the main exterior part of a compressor, and production of shell bodies has increased along with a growing demand for air conditioners, refrigerators, air compressors, and so on. Cracks frequently occur in the process of welding a shell body. In this study, a deep drawing process for creating a shell body from a blank is developed. The technique consists of a four-step deep drawing and a two-step trimming process. Analysis is performed by DEFORM software to examine the safety of the deep drawing and trimming processes. The deep drawing process for the shell body developed in this study would have wide application in many industrial fields.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.7
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• pp.2118-2133
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• 1996

A preform is designed by the backward tracing scheme of the rigid-plastic finite element method(FEM) for net-shape shell nosing components without machining after forming. The current process of the shell nosing requires cost-consuming machining to produce final products. Here, the backward tracing scheme of the rigid-plastic FEM, a novel method for preform design of metal forming processes, derives a sound preform for net-shape shell nosing product. The current process is simulated by the rigid-plastic finite element analysis to check the metal flow involved in the forming with a trial preform and its modified preform. The two preforms are found to be inadequate for net-shape shell nosing product. The first application of the back ward tracing scheme derives a preform producing a not-shape shell nosing product. The first application of the backward tracing scheme derives a preform producing a net-shape product numerically, but it is difficult to be formed economically as a preform. Thus an improved preform is designed by the badkward tracing scheme, which is suitable for net-shape manufacturing of the shell nosing components in view of economy of production and forming characteristics of the product. The preform in the current process and a modified preform are confirmed by a series of experiments and the results give the same deformation with the numerical ones. Finally the newly designed preform by the FEM was experimentally proved to be adequate in obtaining net-shape products.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1995.03a
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• pp.224-232
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• 1995

A process is designed by the backward tracing scheme of the rigid-plastic FEm for net-shape shell nosing component without machining after forming. The current process of the shell nosing industry requires cost-consuming machining to produce final product . The backward tracing scheme of the rigid-plastic FEM, a novel method in preform design of metal forming processes , derives a sound preform for net-shape shell nosing product . The current process is simulated to check the metal flow involved informing with a trial preform and its modified preform. It is found that the two preforms are not suitable for net-shape shell nosing product. Finally, a preform is desinged by the backward tracing scheme, which is suitable for net-shape manufacturing of the shell nosing component.

• Special Issue of the Society of Naval Architects of Korea
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• 2011.09a
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• pp.32-35
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• 2011

Template has been widely used for hull forming process in most of shipyards. It is used to estimate the curvature of deformed shape in comparison with design shape. SHI (Samsung Heavy Industry) had used AutoKon system for ship manufacturing design in the past. The AutoKon used the global coordinate system of ship (frame, water line and so on) to create template data. It brought the mismatched angles between templates and a curved shell plate. The mismatched angle is measured by forming worker to place template on shell forming stage. However, the mismatched angle is difficult to place template with exactly required angle because the shell plates have various curvature and size. It causes incorrect shape of formed shell plates. The attached angle of template should be 90 degree to place template easily on forming shell plates. Currently, SHI has been applied GSCAD for ship manufacturing design process which is 3D solid modeling system. The GSCAD is the rule-based system which can automate 3D modeling and control the manufacturing data by rule. The rule can easily provide methods to create and automate template object with regular attached angle in comparison with AutoKon system. Therefore, SHI developed new template rule which it can automatically create template object with regular attached angle in GSCAD.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.3
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• pp.329-334
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• 2011

The characteristic of sheet metal process is the few loss of material during process, the short processing time and the excellent price and strength. The static implicit finite element method is applied effectively to analyze stamping processes from using AutoForm software. The simulation analysis can be applied to the membrane elements and shell elements. Membrane elements can be applied to good efficiency, but lower than the accuracy of shell elements. Therefore, simple drawing process applies membrane element, and spring-back and analysis of stamping process are judged that it is most efficient that apply shell clement. This study, the simulated results for stamping processes are shown and discussed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.402-405
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• 2005

Such press-forming process are the used machine ability and the characteristic, used material, tile accuracy of the part, condition of a process are considered the designed. In order to estimate in automotive sheet forming processes used AutoForm software. A through in simulation result comparison with experimentation result, it was possible to know that much the same estimated spring-back through a forming analysis. By making apply this to an industrial site the productivity improvement and cost reduction etc. effect able was predicted.