• Composites Research
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• v.13 no.1
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• pp.69-77
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• 2000

This paper presents a modified arc-length method for the nonlinear finite element analysis of a structure which is loaded in incremental and fixed forces, simultaneously. The main idea of the method is to separate the displacement term by the constant force from that by the incremental force. Presented method is applied to the nonlinear analysis of isotropic shell structures separately loaded by lateral pressure or compression, and shows the excellent agreement with previous results. As an illustrative example of the applicability of the present algorithm, a parametric study is performed on the nonlinear buckling analysis of composite cylindrical panels under the combined load of the incremented compression and the constant lateral pressure.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.8-13
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• 2010

An effective control of the axial thrust of a turbopump is one of the critical issues for obtaining its operational stability. Axial thrusts of the fuel pump for the 75-ton class rocket engine under development were measured with water as a test propellant at a room temperature. According to the test results, the axial thrust of the fuel pump seemed to satisfy the axial force condition of its bearing. Also, the thrust was increased as a whole when the flowrate of the pump was decreased. Furthermore it was found that the thrust and the leakage flowate were modified when the gaps between the floating ring seals and the impeller were changed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.5
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• pp.562-569
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• 2007

This paper presents plastic limit loads and approximate J estimates for axial through-wall cracked pipe bends under internal pressure and in-plane bending. Geometric variables associated with a crack and pipe bend are systematically varied, and three possible crack locations (intrados, extrados and crown) in pipe bends are considered. Based on small strain finite element limit analyses using elastic-perfectly plastic materials, effect of bend and crack geometries on plastic limit loads for axial through-wall cracked pipe bends under internal pressure and in-plane bending are quantified, and closed-form limit solutions are given. Based on proposed limit load solutions, a J estimation scheme for axial through-wall cracked pipe bends under internal pressure and in-plane bending is proposed based on reference stress approach.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1521-1528
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• 2012

The present paper provides the elastic stress intensity factors (SIFs) and the crack opening displacements (CODs) of a thick-walled pipe with a slanted axial through-wall crack. For estimating these elastic fracture mechanics parameters, systematic three-dimensional elastic finite element (FE) analyses were performed by considering geometric variables, i.e., thickness of pipe, reference crack length, and crack length ratio, affecting the SIFs and CODs. As for loading condition, the internal pressure was considered. Based on the FE results, the SIFs and CODs of slanted axial through-wall cracks in a thickwalled pipe along the crack front and the wall thickness were calculated. In particular, to calculate the SIFs of a thick-walled pipe with a slanted axial through-wall crack from those of a thick-walled pipe with an idealized axial through-wall crack, a slant correction factor representing the effect of the slant crack on the SIFs was proposed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.1-7
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• 2020

Although the temperature load is an important load among the various loads affecting the behaviors of general rahmen-type temporary bridges (GRTB), no study of the thermal load has been carried out. In the case of GRTB, horizontal displacement should be free, and the generated internal force should be minimized to reduce stress due to a temperature load. Sliding girder type bridge (SGTB) allows the axial deformation due to thermal load, and decreases the axial stress and delivers bending stress. This study examined the temperature behavior of an SGTB. Structural analysis was carried out for four types of spans (eq, 10, 20, 30, and 40m) and three types of pier heights (eq, 2, 4, and 6m) along with the GRTB. The applied loads were a fixed vertical load and an axial temperature load. The friction coefficient was 0.4, which is a representative value of a steel girder. Consequently, the stress of the SGTB increased with increasing span length, regardless of the temperature load. The stress of the GRTB increased with increasing temperature and span length. Compared to the GRTB, the stress of the SGTB decreased by 20% to 50% at the center of the girder and by 50% to 90% at the bottom of the pier. This could secure the structural efficiency compared to the GRTB with the same specifications.

• Journal of the Korea Concrete Institute
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• v.22 no.2
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• pp.273-282
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• 2010

The purposes of this study are to verify the existing model and to propose a rational model for the fracture characteristic of reinforcing steel which is manufactured in Korea being subjected to cyclic loading. This investigation deals with modeling of the low-cycle fatigue behavior for longitudinal reinforcement steel of reinforced concrete bridge substructure (piles and columns of piers). The proposed low-cycle model of longitudinal steel is modeled based on 81 experimental data. The non-linear analysis program was developed using the proposed low-cycle model. The non-linear analysis are applied to the 6 circular bridge column test results and the accuracy of proposed model is discussed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1A
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• pp.1-7
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• 2011

This paper deals with buckling loads of the column with the constant surface area. The shape function of variable column depth is chosen as the linear taper. The ordinary differential equation governing buckled shapes of the column is derived based on the dynamic equilibrium equation of such column subjected to an axial load. Three kinds of end constraint of hinged-hinged, hinged-clamped and clamped-clamped are considered in numerical examples. Effects of the column parameters on buckling loads are extensively discussed. Especially, section ratios of the strongest column are calculated, under which the maximum, i.e. strongest, buckling loads are achieved. Also the buckled shapes are obtained for searching the nodal points where the inner transverse supports are simply installed to increase the buckling loads.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.297-302
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• 1998

유한요소법을 이용하여 스프링으로 연속 지지되고 축방향 하중이 작용하는 핵연료봉의 자유진동 해석올 수행하였다. 본 해석에는 지지격자 지지점에서 핵연료봉의 변위가 구속되지 않는 실제 경계조건을 반영하였다. 이러한 경계조건은 지지점 스프링 상수에 의하여 핵연료봉 해석모델의 탄성항이 약화되는 현상을 반영할 수 있어서 지지점이 구속된 기존의 모델보다 고유진동수를 작게 예측한다. 스프링 상수가 어떤 임계값 이하를 갖는 경우 고유진동수 뿐만 아니라 모드형상도 크게 변하기 때문에 지지점을 구속한 모델에 의한 해석은 실제 진동현상을 상당히 왜곡 할 수 있다. 핵연료봉에 작용하는 축방향력이 인장력에서 압축력으로 감소함에 따라 고유진동수도 감소하지만 핵연료봉의 고유형상은 변하지 않았다. 지지격자 스프링 상수의 점진적인 감소와 핵연료봉 축방향 압축력의 감소를 동시에 적용하는 경우 고유 진동수는 두 변수를 별도로 적용했을 때 얻은 최소값의 변화에 따르는 경향을 나타내었다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1203-1214
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• 2000

In this paper, a failure model for co-cured steel-composite tubular single lap joints has been proposed incorporating the nonlinear mechanical behavior of steel adherends and different failure mode s such as steel adherend failure and composite adherend failure. The characteristics of the co-cured steel-composite tubular single lap joint were investigated with respect to the test temperature, the stacking sequence of composite adherend, the thickness ratio of steel adherend to composite adherend, and the scarf ratio of steel adherend. Thus, the optimum design method for the co-cured steel-composite tubular single lap joint was suggested.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.265-270
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• 2010

This paper presents the rocket motor support structure to position solid rocket engine within a missile fuselage. When the rocket motor is mounted inside a missile fuselage, fuselage structure must be designed to withstand various structural problems resulting from inserted rocket motor such as axial thrust force, shock/vibration, axial deformation of the rocket motor tank in addition to the flight loads. The motor support structure system proposed in this paper proved to be very simple and efficient while satisfying all the design requirements.