• 조명전기설비학회논문지
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• 제28권1호
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• pp.45-49
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• 2014

Torque of an induction motor is generally calculated by simplified equivalent circuit. However, the torque has an error since it is calculated by simplified equivalent circuit. In this paper, stator and rotor currents, torque, efficiency, and power factor are derived from the equivalent circuit of an induction motor using mesh analysis method. Then, they are compared with those calculated from simplified equivalent circuit.

• International Journal of Naval Architecture and Ocean Engineering
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• 제4권3호
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• pp.313-321
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• 2012

Vibration analysis of a thin-walled structure can be performed with a consistent mass matrix determined by the shape functions of all degrees of freedom (d.o.f.) used for construction of conventional stiffness matrix, or with a lumped mass matrix. In similar way stability of a structure can be analysed with consistent geometric stiffness matrix or geometric stiffness matrix with lumped buckling load, related only to the rotational d.o.f. Recently, the simplified mass matrix is constructed employing shape functions of in-plane displacements for plate deflection. In this paper the same approach is used for construction of simplified geometric stiffness matrix. Beam element, and triangular and rectangular plate element are considered. Application of the new geometric stiffness is illustrated in the case of simply supported beam and square plate. The same problems are solved with consistent and lumped geometric stiffness matrix, and the obtained results are compared with the analytical solution. Also, a combination of simplified and lumped geometric stiffness matrix is analysed in order to increase accuracy of stability analysis.

• 한국강구조학회 논문집
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• 제25권4호
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• pp.359-368
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• 2013

본 논문은 중공튜브 및 샌드위구조 형식을 주로 갖는 GFRP 복합소재 바닥판의 기본설계에서 전체 유한요소 모델링을 이용하지 않고 탄성등가 모델링을 이용한 간편 해석 방법을 제시하였다. 제시된 간편 해석 방법의 타당성 검증을 위해서 ANSYS 프로그램이 사용되었으며, 전체 유한요소 모델링과 탄성등가모델링을 이용한 해석값을 각각 비교하였다. 또한 본 논문에서 제안된 GFRP 복합소재 바닥판 간편 해석법에 의한 해석 결과를 비교하기 위해 각형 튜브를 갖는 샌드위치 구조형식 GFRP 복합소재 바닥판의 4점 휨시험인 실내실험결과를 수행하였다. 해석 결과와 실험 결과 내용을 비교분석하였다. 제시된 간편해석 방법은 GFRP 복합소재 바닥판의 기본설계시 사용하기에 적용성이 있음을 확인되었다.

• 소음진동
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• 제9권5호
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• pp.975-983
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• 1999

This paper describes the dynamic characteristics of the joint structures in case of using the simplified beam model in the F. E. analysis. The modeling errors, when replace the shell with the beam, are investigated through F. E. normal modes analysis. Normal mode analysis were performed to obtain the natural frequencies of the L and T shaped joints with various type of channels. The results were analyzed to access the effects of the models on the accuracy of F.E. analysis by identifying the geometric factors which cause the error. The geometric factors considered are joint angle, channel length, thickness and area ratio of the hollow section to the filled one. The joint stiffness evaluation technique is developed in this study using normal modes analysis with Lumped Mass. With this method, the progressively improved results of F. E. analysis are obtained using the simplified beam model. The static and normal modes analysis are performed with the joint stiffness values obtained by the Kazunori Shimonkakis' virtual stiffness method and the proposed method and these simplified modeling errors are compared.

• Journal of Advanced Marine Engineering and Technology
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• 제26권1호
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• pp.48-58
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• 2002

There is a purpose of this study for the proposal of the optimum technique utilized for the vibration design initial step. The stiffened plate structure for the ship hull is made for analysis model. To begin with, dynamic characteristics of stiffened plate structure is analysed using FEM. Main vibrational mode of the structure is decided in the analytical result of FEM. The simplified equation on the natural frequency of the main vibrational mode is induced. Next, sensitivity analysis is carried out using the simplified equation, and rate of change of dynamic characteristics is calculated. Then, amount of design variable is calculated using this sensitivity value and optimum structural modification method. The change of natural frequency is made to be an objective function. Thickness of panel, cross section moment of stiffener and girder become a design variable. The validity of the optimization method using simplified equation is examined. It is shown that the result effective in the optimum modification for natural frequency of the stiffened plate structure.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.259-262
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• 2008

This paper introduces a simplified method to consider forming effects in a car crash analysis. Representative value was used to consider forming effects simply. Four representative values, which are the mean value of thicknesses and effective plastic strains at nodes, the median of thicknesses and effective plastic strains at nodes, were evaluated. A crash analysis of a front side member shows that analysis results from the suggested methods are similar to those from the conventional method to consider forming effects. Use of the mean effective plastic strain shows the best results. A car crash analysis for a ULSAB/AVC model under the condition of US SINCAP were carried out to demonstrate the validity of the suggested method. Analysis results show that the error of suggested method is less than 1.5%.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1994년도 가을 학술발표회 논문집
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• pp.103-112
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• 1994

Various kinds of fatigue failures of ocean structures were reported and the importance of fatigue life estimation at the design state is significantly recognized and various kinds of analysis approaches have been discussed. In this paper characteristics of the simplified method proposed here and the spectral method are studied and the elements of the approach are discussed. The merits and demerits of the forementioned analysis schemes are studied and the relating parameters such as SCF and S-N curves are also investigated. The simplified fatigue analysis approach and tile spectral fatigue analysis technique is applied for the analysis of bracing members of typical semi-submersible drilling rig structure for the verification of the usage of two methods and the sensitivity study has been performed using the simplified method. The result from the spectral analysis give a more realistic picture of the fatigue life of the offshore structure considered here.

• Journal of Ship and Ocean Technology
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• 제3권3호
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• pp.13-24
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• 1999

In this paper, a 2-dimensional novel beam element is developed and a method to replace the 3-dimensional analysis with 2-dimensional analysis is proposed. The developed novel beam element named rigid-ended beam element can consider the effect of three kinds of span points within one element, which was impossible in modeling with the ordinary beam element. Calculated results for the portal frame using the rigid-ended beam element agree with the results using membrane element. And also, the proposed simplified 3- dimensional analysis method which includes two step analysis using influence coefficients shows good accuracy. Structural analysis using the rigid-ended beam element and the simplified 3-dimensional method is revealed to have good computing efficiency due to unnecessity of the elements corresponding to the brackets and simplification of 3-dimensional analysis.

• Structural Engineering and Mechanics
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• 제12권1호
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• pp.71-84
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• 2001

The objective of this paper is to develop a simplified method that could predict the strength of concrete filled steel tube (CFT) columns applicable to high strength material under combined axial compression and flexure. The simplified method for determining the strength of CFT columns is based on the interaction curve of the section approached by a polygonal connection of the points. These points are determined by using symmetrical properties of the CFT section. For each point, a simple equation is proposed to determine the strength of the slender columns under compression and flexure. The simple equation was adjusted with results of elasto-plastic analysis results. Validation of the simplified method is undertaken by comparison with data from the test conducted at Kyushu University. These results confirm the fact that the simplified method could accurately and reliably predict the strength of CFT columns under combined axial compression and flexure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.596-601
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• 2007

A simplified finite element analysis method is proposed to calculate elasto-plastic responses of general hardening materials. The method provides an effective tool to calculate structural elasto-plastic responses. Numerical examples have demonstrated that its computational efficiency is very much higher than that of the incremental elasto-plastic finite element analysis, and computational results are accurate enough to meet the need of engineering practice. Compared with the general elasto-plastic incremental finite element analysis, the proposed method can avoid the incremental iteration of nodal displacements and the constitutive equation integration at each Gauss integral point, and computational results are accurate enough to meet the need of engineering practice.