• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1772-1775
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• 2003

The stiffness of multi-articulated industrial robots is very weak, because their structure is an articulated type with some links and joints. Thus it is known that cutting processes for metals are not accepted in machine shop well, but they have a lot of merits for cutting processes, for example. drilling, tapping. and engraving etc., because of the characteristics of their high degree of freedom. The temptation of cutting aluminium was carried out to investigate the feasibility and the limitations or constrains for cutting metals on them. First the mode shapes of 6-axes FANUC welding robot were taken and analysed, and next the cutting processes were practically carried out on it. The results of study were found out to show the feasibility of cutting processes at end-milling under 6mm of tool diameter. as well as to have some limitations and constrains, for examples, surface roughness and feed rate, depth of cut, cutting force etc..

• Bulletin of the Society of Naval Architects of Korea
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• v.13 no.2
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• pp.13-43
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• 1976

A potential flow approach is used to develop a method and an associated computer program for floating marine structures of general configuration in wave of all water depths with arbitrary heading. It computes the total force distributions and six degrees-of-freedom motion. The hydrodynamic-force equations and derived become identical under certain assumptions to the equations commonly used by the offshore industry, and the two methods are compared in detail. The computed motions of all six degree agree quite well with model-scale and full-scale experimental data for two typical semisubmersible drilling rigs in finite-depth water. Also the presented motion computations are more accurate than a previous work by the second approach. The present computations use experimentally validated or determined values of frequency-dependent hydrodynamic coefficients with the effects of the free surface and both finite and infinite water depths. The present method generates sufficient computation accuracy to use for practical design applications.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.11
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• pp.1765-1772
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• 1997

The layered composites have a character to change of structure stiffness with respect to the layup angles. The deformations in the fan-blades to be initially designed by considering efficiency and noise, etc., which arise due to the pressure during the fan operation, can make the fan inefficient. Thus, so as to minimize the deformations of the blades, it is needed to increase the stiffness of the blades. An investigation has been performed to develop the three dimensional layered composite shell element with the drilling degree of freedom and the optimization module for finding optimal layup angles with sensitivity analysis. And then they have been verified. In this study, the analysis model is engine cooling fan of automobile. In order to analyzes the stiffness of the composite fan blades, finite element analysis is performed. In addition, it is linked with optimal design process, and then the optimal angles that can maximize the stiffness of the blades are found. In the optimal design process, the deformations of the blades are considered as multiobjective functions, and this results minimum bending and twisting simultaneously.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.2
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• pp.36-43
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• 2010

In this study, the buckling loads and mode shapes characteristic of circular and non-circular(elliptical) closed composite shells were analyzed. To analyses the buckling behaviors, we develop and report an improved generalized shell element called 4EAS-FS through a combination of enhanced assumed strain and the substitute shear strain fields. A flat shell element has been developed by combining membrane element with drilling degree-of-freedom and a plate bending element. The combined influences of length, thicknesses, cross-sectional parameters, and fiber-angle on the critical buckling loads and mode shapes of circular and non-circular(elliptical) closed shells are examined.

• Interaction and multiscale mechanics
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• v.4 no.1
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• pp.17-34
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• 2011

This paper deals with the modeling of the plane frame structure-foundation-soil system. The superstructure along with the foundation beam is idealized as beam bending elements. The soil medium near the foundation beam with stress concentrated is idealized by isoparametric finite elements, and infinite elements are used to represent the far field of the soil media. This paper presents the modeling of shear wall structure-foundation and soil system using the optimal membrane triangular, super and conventional finite elements. Particularly, an alternative formulation is presented for the optimal triangular elements aimed at reducing the programming effort and computational cost. The proposed model is applied to a plane frame-combined footing-soil system. It is shown that the total settlement obtained from the non-linear interactive analysis is about 1.3 to 1.4 times that of the non-interactive analysis. Furthermore, the proposed model was found to be efficient in simulating the shear wall-foundation-soil system, being able to yield results that are similar to those obtained by the conventional finite element method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3A
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• pp.457-464
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• 2006

Fiber-reinforced composite materials due to their high specific strength, high stiffness and light weight are becoming increasingly used in many engineering industry, especially in the aerospace, marin and civil, etc. In this paper, the buckling load and mode shapes of composite laminates with elliptical cross-section including transverse shear deformations are analyzed. For solving this problems, a versatile flat shell element has been developed by combining a membrane element with drilling degree-of-freedom and a plate bending element. Also, an improved shell element has been established by the combined use of the addition of enhanced assumed strain and the substitute shear strain fields. The combined influence of shell geometry and elliptical cross-sectional parameter, fiber angle, and lay-up on the buckling loads of elliptical cylinder is examined. The critical buckling loads and mode shapes analyzed here may serve as a benchmark for future investigations.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.1
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• pp.21-30
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• 2004

This study deals with free vibrations of laminated composite structures with a channel section using finite element method. In this paper, the mixed finite element method using Lagrangian and Hermite interpolation functions is adopted and a high-order plate theory is used to analyze laminated composite non-prismatic folded plates with a channel section more accurately for free vibration. The theory accounts for parabolic distribution of the transverse shear stress and requires no shear correction factors supposed in the first-order plate theory. An 32×32 matrix is assembled to transform the system element matrices from the local to global coordinates using a coordinate transformation matrix, in which an eighth drilling degree of freedom (DOF) per node is appended to the existing 7-DOF system. The results in this study are compared with those of available literatures for the conventional and first-order plate theory. Sample studies are carried out for various layup configurations and length-thickness ratio, and geometric shapes of plates. The significance of the high-order plate theory in analyzing complex composite structures with a channel section is enunciated in this paper.