• Title, Summary, Keyword: Bending Moment

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Mean moment effect on circular thin-walled tubes under cyclic bending

  • Chang, Kao-Hua;Pan, Wen-Fung;Lee, Kuo-Long
    • Structural Engineering and Mechanics
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    • v.28 no.5
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    • pp.495-514
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    • 2008
  • In this paper, experimental and theoretical investigations of the effect of the mean moment on the response and collapse of circular thin-walled tubes subjected to cyclic bending are discussed. To highlight the influence of the mean moment effect, three different moment ratios r (minimum moment/ maximum moment) of -1, -0.5 and 0, respectively, were experimentally investigated. It has been found that the moment-curvature loop gradually shrinks with the number of cycles, and becomes stable after a few cycles for symmetric cyclic bending (r = -1). However, the moment-curvature loop exhibits ratcheting and increases with the number of cycles for unsymmetric cyclic bending (r = -0.5 or 0). In addition, although the three groups of tested specimens had three different moment ratios, when plotted in a log-log scale, three parallel straight lines describe the relationship between the controlled moment range and the number of cycles necessary to produce buckling. Finally, the endochronic theory combined with the principle of virtual work was used to simulate the relationship among the moment, curvature and ovalization of thin-walled tubes under cyclic bending. An empirical formulation was proposed for simulating the relationship between the moment range and the number of cycles necessary to produce buckling for thin-walled tubes subjected to cyclic bending with different moment ratios. The results of the experimental investigation and the simulation are in good agreement with each other.

A Discussion on Measurement of Springback Ratio Using Winding Bend Rig (감아굽힘 장치를 이용한 스프링백 비의 측정에 대한 역학적 검토)

  • 김용우
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.10 no.2
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    • pp.1-9
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    • 2001
  • To measure springback ratio of thin sheet or plate, winding bend rig is made. It bends a specimen with keeping its curva-ture constant and measure the bending angles before and after release of bending load. To check the performance of the bend rig, we calculated the bending moment by two ways which are based on simple beam theory. One is that the bending moment is calculated by using the results of bending test, and the other is that the moment is calculated by using the results of tensile tests. The former may entails the effect of the other is that the moment is calculated by using the results of tensile tests. The former may entails the effect of the friction between bending pin of the rig and surface of specimen, but the latter does not contain any effects of the friction since the bending moment is obtained by using tensile tests. Never-theless, the values of the two bending moments shows the same level of bending moment, which implies that the friction does not influence on the presence of friction within the scope of the test performed in this experiment. This phenomenon is explained theoretically by using moment equilibrium.

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A Discussion on Measurement of Springback Ratio Using Winding Bend (감아굽힘 시험장치의 제작과 스프링백 비의 시험법에 대한 역학적 검토)

  • 김용우
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.95-101
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    • 2000
  • To measure springback ratio of thin sheet or plate, winding bend rig is made. It bends a specimen with keeping its curvature constant and measures the bending angles before and after release of bending load. To check the performance of the bend rig, we calculated the bending moment by two ways which are based on simple beam theory. One is that the bending moment is calculated by using the results of bending test, and the other is that the moment is calculated by using the results of tensile tests. The former may entails the effect of the friction between bending pin of the rig and the surface of specimen, but the latter does not contain any effects of the friction since the bending moment is obtained by using tensile tests. Nevertheless, the values of the two bending moment shows the same level of bending moment, which implies that the friction does not influence on the value of springback ratio in spite of the presence of friction within the cope of the test performed in this experiment.

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A Study on the Bending and Seismic Performance of High Performance Cold Forming Composite Beam

  • Choi, Young Han;Kim, Sung Bae;Hong, Hyung Ju;Kim, Sang Seup
    • International journal of steel structures
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    • v.18 no.5
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    • pp.1772-1783
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    • 2018
  • Nowadays, the researches about composite structure system are being implemented in various fields, and many steel structures are designed based on that. In this study, the bending and seismic performance of the newly developed high-performance cold forming composite beam are evaluated by several experiments. As a result of the bending performance test, the bending moment of beam was increased stably depending on the depth and plate thickness of beam, and it is considered that the bending moment can be evaluated by the equation of a composite beam design. As a result of the seismic performance test, it was verified that sufficient seismic performance was obtained despite the increase of a negative moment rebar and depth of beam. In addition, the nominal bending moment has obtained the strength above the plastic bending moment, and also the plastic rotation angle has satisfied the requirement of composite intermediate moment frame.

Estimation of Plastic Bending Moment of Offshore Pipelines (해저관로의 대변형 굽힘에 의한 소성 모멘트 추정)

  • 이종현;최한석;이승건
    • Journal of Ocean Engineering and Technology
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    • v.17 no.2
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    • pp.21-26
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    • 2003
  • The reel-lay method of submarine pipelines a continuous string of pipe coiled onto a reel. Assembly of this pipe that is string is accomplished onshore by welding, and nondestructive testing is carried out prior to coiling the pipe. The total length of pipes on the reel depends on the reel and pipe diameters. Pipeline installation is accomplished by uncoiling, straightening the pipe, and laying out the pipe string onto the seabed as the barge moves forward. Installation associated with coiling and uncoiling is related to the bending moment and strain relationship of the pipeline, A highgrade pipe material is required when the reel-lay method is used. This paper is concerned with the highly plastic bending moment of the pipeline, including the effect of ovality. Moment calculation in the pipe is accomplished by the numerical method, including the variable ovalities during the plastic bending of the pipe string. The new calculation method of the high plastic bending moment was applied to the reel-lay method.

The Fatigue Behavior and Delamination Properties in Fiber Reinforced Aramid Laminates -Case (I) : AFRP/Al Laminates-

  • Song, Sam-Hong;Kim, Cheol-Woong
    • Journal of Mechanical Science and Technology
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    • v.17 no.3
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    • pp.343-349
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    • 2003
  • The fuselage-wing intersection suffers from the cyclic bending moment of variable amplitude. Therefore, the influence of cyclic bending moment on the delamination and the fatigue crack propagation behavior in AFRP/Al laminate of fuselage-wing was investigated in this study. The cyclic bending moment fatigue test in AFRP/Al laminate was performed with five levels of bending moment. The shape and size of the delamination Lone formed along the fatigue crack between aluminum sheet and aramid fiber-adhesive layer were measured by an ultrasonic C-scan. The relationships between da/dN and ΔK, between the cyclic bending moment and the delamination zone size, and between the fiber bridging behavior and the delamination zone were studied. As results, fiber failures were not observed in the delamination zone in this study, the fiber bridging modification factor increases and the fatigue crack growth rate decrease and the shape of delamination zone is semi-elliptic with the contour decreasing non-linearly toward the crack tip.

An Analytical Study on the Deformation Behavior of the Reinforced Concrete Circular Section Column under Bi-Axial Bending Moment and Axial Force (2축휨가 축력을 받는 철근콘크리트 원형단면주의 변형성상에 관한 해석적연구)

  • 정호길
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.163-172
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    • 1997
  • This paper is a study on the deformation behavior of the reinforced concrete circular section column carrying bi-axial bending moment and axial force. That is, this is to clarify the deformation behavior of the reinforced concrete circular section column carrying bi-axial bending moment and axial force by analytic methods. The deformation behavior of circular section column under bi-axial uni-axial bending moment and axial force are compare with those of a square section column under the same conditions. Those of circular section column under bi-axial bending moment are decreased as compared with those of circular section column under uni-axial bending moment. The results mentioned above are the same under the axial force of 7tons and 11tons.

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Analysis and Process Design of Hot Pipe Bending Process With Small Bending Radius (작은 곡률반경 파이프 벤딩을 위한 열간 파이프 벤딩공정 해석 및 설계)

  • 류경희;김동진;김병민;이동주
    • Transactions of Materials Processing
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    • v.10 no.4
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    • pp.329-337
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    • 2001
  • The finite element simulation model and the program to calculate the reverse moment have been developed to analyse the stress state and deformation of pipe bending using local induction heating with small bending radius in this study. The reverse moment that is to be applied on the bending arm to control the wall thinning ratio of the bending outside to within a particular value. Even though the demand of pipes with small bending radius is increasing in power plants and ship buildings, the welded elbows are still widely used. The bending process with or without a reverse moment acting on the bending arm has been simulated. The reverse moments calculated from the developed program are in good agreement with the finite element simulations and the experiments.

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Prediction of the wave induced second order vertical bending moment due to the variation of the ship side angle by using the quadratic strip theory

  • Kim, Seunglyong;Ryue, Jungsoo;Park, In-Kyu
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.10 no.3
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    • pp.259-269
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    • 2018
  • In this study, the second order bending moment induced by sea waves is calculated using the quadratic strip theory. The theory has the fluid forcing terms including the quadratic terms of the hydrodynamic forces and the Froude-Krylov forces. They are applied to a ship as the external forces in order to estimate the second order ship responses by fluid forces. The sensitivity of the second order bending moment is investigated by implementing the quadratic terms by varying the ship side angle for two example ships. As a result, it was found that the second order bending moment changes significantly by the variation of the ship side angle. It implies that increased flare angles at the bow and the stern of ships being enlarged would amplify their vertical bending moments considerably due to the quadratic terms and may make them vulnerable to the fatigue.

A Study on the Longitudinal Strength of the Ship Hull(I) (선체 종강도에 관한 연구(I))

  • 고윤섭
    • Journal of the Korean Institute of Navigation
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    • v.8 no.2
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    • pp.43-50
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    • 1984
  • When the static load is applied to the ship's hull the deflection due to the bending moment from longitudinal direction has not been considered in the usual calculation of maximum bending moment. In fact, however, the deflection of ship's hull must be affected by the above-stated bending moment, and in this case the value of the maximum bending moment would be lessened in comparision with the result of usual calculation. In this paper, the author at first calculated the difference between the two values in case of rectangular barge, and suggested a practical criterion of longitudinal strength.

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