• Journal of Power System Engineering
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• v.20 no.2
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• pp.5-16
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• 2016

Generally, methods using transfer techniques, like the transfer matrix method and the transfer stiffness coefficient method, find natural frequencies using the sign change of frequency determinants in searching frequency region. However, these methods may omit some natural frequencies when the initial frequency interval is large. The Sylvester-transfer stiffness coefficient method ("S-TSCM") can always obtain all natural frequencies in the searching frequency region even though the initial frequency interval is large. Because the S-TSCM obtain natural frequencies using the number of natural frequencies existing under a searching frequency. In this paper, the algorithm for the free vibration analysis of axisymmetric conical shells was formulated with S-TSCM. The effectiveness of S-TSCM was verified by comparing numerical results of S-TSCM with those of other methods when analyzing free vibration in two computational models: a truncated conical shell and a complete (not truncated) conical shell.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04a
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• pp.79-82
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• 2002

Induction heating is widely used in today's industry, in operations such as metal hardening, preheating for forging operations, melting or cooking. In this paper, it was presented the magneto-thermal analysis of an induction heating jar(IH-JAR) with the material value of the stainless and the aluminum for efficient design. The magnetic field intensity inside the axisymmetric shaped cooker was analyzed using three-dimensional axisymmetric finite element method(FEM) and the effectual heat source was obtained by ohmic losses from eddy currents induced in the jar. The heat was calculated using the heat source and heating equation. Also, it was represented the temperature characteristics of the IH-JAR according to time and relative permeability in stainless parts and in aluminum parts.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.330-336
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• 1989

In analyzing the axisymmetric backward extrusion process a new method of analysis using upper-bound theorem is proposed in which the plastic zone and dead metal zone cam be predicted. Experiments are carried out with commercial aluminum. The metal flow on the meridional plane has been visualized experimentally by using the gridded specimens. It is shown that the theoretical results both in extrusion load and deformation pattern are in good agreement with the experimental results and they can be used for effective punch and die design to consider various process parameters in axisymmetric backward extrusion.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.137-142
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• 2003

In automotive brake systems, the frictional heat generated can cause high temperature at the interface of rotor and pad which may deteriorate the material properties of the sliding parts and can result in brake fade. Conventionally, a pie-shaped 3-dimentional model is adopted to calculate temperature of ventilated disk using finite element method. To overcome the difficulties in preparing 3D finite element model and reduce the computational time required, the ventilated rotor is to be analyzed, in this study, as an axisymmetric finite element model in which, taking into considerations the effects of cooling passages, a homogenization technique is used to obtain the equivalent thermal properties and boundary conditions for the elements placed at the vent holes. Numerical tests show the proposed procedure can be successfully applied in practice, replacing 3-dimensional thermal analysis of ventilated disk.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.2
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• pp.28-38
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• 1990

The study is concerned with the theoretical and experimental investigation of axisymmetric fluid pressure-driven hydroforming of sheet metal by forming over the die cavity. The rigid-plastic finite element method is employed to calculate the stress and strain distribution. The effect of blank size and die radius is also studied in the finite element analysis. Experiments are carried out for hydroforming of cold-rolled steel sheets under various process conditions. The computational results are compared with the experimental results for the forming pressure vs. pole displacement relations and strain distributions. Comparison has shown that theoretical predictions by the finite element method are in good agreement with the experiment with the experimental observations. Thus, it is shown that the rigid-plastic finite element method is effectively used in the analysis of axisymmetric fluid pressure-driven hydroforming process.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.3
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• pp.485-497
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• 2017

The pogo phenomenon refers to a type of multidiscipline-related instability found in space launch vehicles. It is caused by coupling between the fuselage structure and other structural propulsion components. To predict the pogo phenomenon, it is essential to undertake adequate structural modeling and to understand the characteristics of the feedlines and the propulsion system. To do this, a modal analysis is conducted using axisymmetric two-dimensional shell elements. The analysis is validated using examples of existing launch vehicles. Other applications and further plans for pogo analyses are suggested. In addition, research on the pogo phenomenon of Saturn V and the space shuttle is conducted in order to constitute a pogo stability analysis using the results of the present modal analysis.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.854-859
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• 2000

When the round bar with step is twisted and bent, stress concentration is occurred in the irregular geometric parts. Two dimensional axisymmetric stress analysis is carried out according to the geometric change of the stress-concentrated part of round bar with step. Three dimensional cases are also investigated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.4
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• pp.731-742
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• 1998

Bolted opening structures is widely applied for class 1 machinery of nuclear plant with strict design requirement. As the shape of the bolted opening structure is non-axisymmetric due to the existence of stud bolts although it is almost axi-symmetric, 3D analysis is required to satisfy such kind of design requirements. Because as much as possible trial computations are need to get an optimal design condition in the limited period of basic design, an easy and fast analysis tool is useful in the design stage. In the paper, a transformation technique of non-axisymmetric problem into quasi-axisymmetric has been proposed based on the general purpose commercial code ANSYS. Both the pre-processor which incorporates the technique and prepares data and post-processor which prepares arranged results from the huge output of commercial code have been developed to help the design engineers.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.2
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• pp.53-61
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• 2006

Axisymmetric numerical thermal analysis for a 3-dimensional regenerative cooling system in a rocket engine is carried out. To predict the accurate heat transfer with the stiff temperature distribution, several tests have been conducted for the grid size, the properties variation of the coolant and the combustion gas depending on temperature. The axisymmetric heat flux model is defined using fin efficiencies and is designed to be equivalent to the heat flux of the 3-dimensional coolant channel. For comparison purpose, the 1-dimensional analysis using Bartz equation is also conducted. The performance of the present model in predicting the cooling characteristics of a 3-dimensional regenerative cooling system is compared with the 3-dimensional results of RTE(Rocket Thermal Evaluation). It is found that the present method predicts much closer results to those of RTE code than 1-dimensional analysis.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.1
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• pp.141-152
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• 1993

A generalized method is presented for shape design sensitivity analysis of axisymmetric thermal conducting solids. The shape sensitivity formula of a general performance functional arising in shape optimal design problem is derived using the material derivative concept and the adjoint variable method. The method for deriving the formula is based on standard axisymmetric boundary integral equation formulation. It is then applied to obtain the sensitivity formulas for temperature and heat flux constraints imposed over a small segment of the boundary. To show the accuracy of the sensitivity analysis, numerical implementations are done for three examples. Sensitivities calculated by the presented method are compared with analytic sensitivities for two examples with analytic solutions, and compared with sensitivies by finite difference for a cooling fin example.