• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.4
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• pp.59-66
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• 2008

This paper has proposed a new parameter to interpret the effects of plastic deformation in bending of strips in cylindrical die and punch. With reference to the parameter, we have provided an insight on the separation between strips and punches, the occurrence of the multi-point bending during the process of deformation, the final shapes of strips, and the springback ratios. Also using the parameter, we have considered the different effects between the bending deformation in the cylindrical die and the bending deformation due to pure bending.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.11
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• pp.2696-2704
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• 2000

This paper presents a new laminated plate theory for the cylindrical bending of laminated plated. The theory assumes that in plane displacements vary exponentially through plate thickness. Analytical solutions are derived for simply supported plates subjected to transverse loading. The accuracy of the present theory is examined for unsymmetric laminates, and the numerical results are compared with three-dimensional elasticity solutions of Pagano. The present theory predicts displacements and stresses for very thick plates very accurately. In particular, transverse shear stresses obtained form constitutive equations are predicted very accurately.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.1
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• pp.112-119
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• 1993

A strength and durability estimation system of involute cylindrical gears which are commonly used as power transmission devices is developed on the personal computer, which analyzed and/or evaluates the gear design and the service performance at the point of view of strength and durability. The typical considerations are the bending strength and the sunface durability, and the strength and durability estimations are carried out using the reliable standards of AGMA&ISO. In addition, the finite element analysis (FEM) of tooth bending stress is conducted in order to compare the real maximum stress with the estimaed bending stress by the standard. Therefore, the system is built so that the variables or factors considered differently in those standards and the strength & durability are appraised seperately by each method, and a series of the estimation processes is integrated into the system can be used in the initial design at the view point of strength and durability. And it is useful to the purpose of the trouble-shooting of gear system and the purpose of introducing the methods for maintaining design strength in service, with appraising the strength and durability after design or with appraising the influencing factors, as a whole. Therefore, this strength and durability estimation system can help the aim of automatic design of cylindrical gears.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.594-602
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• 1990

A computer-aided design system of involute cylindrical gears(spur and helical gears) for power transmission is developed, in which the volume of a gear unit is minimized with satisfying various design constraints. As the design constraints, bending strength and pitting resistance of AGMA 218.01, scoring of Dudley's flash temperature, contact ratio, and involute interference of pinion are considered and effective factors for strength calculation(life, reliability, hardness ratio, load distribution, velocity, etc.) are also included. This complicated nonlinear optimization problem is solved by using ALM(Augmented-Lagrange-Multiplier) method with self scaling BFGS(Broydon-Fletcher-Goldfarb-Shanno) method employed for unconstrained optimization programming. This design method can be easily applied to designing power transmission gear unit in the machines of various kinds. It is expected for the proposed method to be a contribution for an automated design of gear unit towards weight minimization, miniaturization and high strength of gear unit.

• Journal of KSNVE
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• v.6 no.1
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• pp.107-114
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• 1996

The damping characteristics of a cylindrical structure containing oil and bearing balls is investigated for external bending forces. The experimental data obtained through the use of bearing balls with viscous oil in a column is given and analyzed. The viscous action of the oil and inertia effects of the balls on the inside of column create a drag force. The drag force dampens the vibration of the column. This study aims to search for an optimum combination of oil and balls which would produce maximum damping. Machining oils of various viscosities along with ball bearings of various sizes place inside cantilevered aluminium tubes of various diameters to create a rig on which the damping properties of the oil and balls can be studied. The contileved tubes are studied in both horizontal and vertical positions in order to gauge the effect of gravity on the system. The actions of the ball in the column and damping characteristics are investigated according to the dimensionless terms. The Buckingham theorem is used to reduce the variables and to predict the damping of an oil ball column. Though the damping ratio remains fairly constant in the horizontal position of column, the damping ratio begins to increase as the ratio of the number of balls and column length rise above 0.28 in the vertical position of oil ball column. The ratio of the ball diameter to column diameter influences the damping ratio with an optimum diameter ratio. Slenderness ratio and gravity effects on the damping ratio ane investigated.

• Journal of the Korean Institute of Gas
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• v.18 no.2
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• pp.10-15
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• 2014

In this paper, the displacement and stress strength safeties have been presented for cylindrical hollow rollers of a wire saw machine. Using the finite element method, the hollow roller with Y-shaped shift and vertical columns between three tubes has been developed to analyze the displacement behavior and stress strength safeties. For the same diameter and length of hollow roller models with a different weight, the displacement behavior safety of Y-shaped shift column and vertical column models is heavily depending on the total length of a hollow roller, which is closely related to the bending moment of a hollow roller structure. But, the stress strength of a hollow roller is more influenced by the cross sectional area of a hollow roller for the similar weight. Thus, this paper recommends Y-shaped hollow roller for increasing the roller strength safety and decreasing a total roller weight.

• Composites Research
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• v.14 no.3
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• pp.42-50
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• 2001

Modeling of damage initiation in singly oriented ply (SOP) Fiber Metal Laminate (FML) under concentrated loading conditions was studied. The finite element method (FEM) base on the first order shear deformation theory is used for th\ulcorner modeling of damage initiation in SOP FML. The failure indices (FI) of the fiber prepreg and the metal laminate were calculated by using the Tasi-Hill failure criterion and the Miser yield criterion, respectively. To verify the present method, the failure analysis was conducted under uniaxial loading and cylindrical bending, then the analysis under concentrated load was conducted. The results show that the analysis is reasonable. An indentation test was conducted to compare a damage initiation load with a calculated FI. The test was conducted under two side clamped conditions to study the fiber orientation effect. Indentation curve was fitted using the Hertz equation and a damage initiation load is defined that the point which deviate the fitted curve from the real indentation curve. The damage initiation loads were obtained under various fiber orientations and compared with calculated FIs. The experiment was well matched with calculated FI. This results shows that the present method is suitable for the damage initiation modeling of SOP FML.