• Title, Summary, Keyword: 임계하중

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Critical Elastic Buckling Load Investigation of Aluminium Alloy A6082-T6 Square plate Subjected to Patch Loading (패치 로딩을 받는 알루미늄 합금 A6082-T6 사각형 판의 임계 탄성좌굴하중 검토)

  • Oh, Young-Cheol;Ko, Jae-Yong
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.20 no.4
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    • pp.451-460
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    • 2014
  • In this paper, we examined the problem of the structural stability according to the patch load of a rectangular plate that reflects the material properties of A6082-T6 is used primarily for marine plant structure. it applied to the four patch loading shapes, the effect of aspect ratio, a boundary condition and calculated the critical elastic buckling load. Calculating the critical elastic buckling load, During the eigenvalue buckling analysis it is applied to the shell181 as 4 node shell element. when the plate subjected to patch loading compare to the plate under a uniform axial compression load, it is possible observed to occur the different elastic buckling behaviour and it could be confirmed that it is affected significantly on a variable position and type of loadings, such as the effect of the aspect ratio. Also, Critical elastic buckling load according to th patch loading type in simply supported rectangular plate a/b=1.0, ${\gamma}b$=200mm are calculated 67%(Loading type I), 119 %(Loading type II), 76 %(Loading type III), 160 %(Loading type IV), respectively. Loading type I and III could be determined with the strong elastic buckling behavior much more than Loading type II and IV.

Critical Loads of Eccentrically Loaded Struts with Thin-Walled Open Sections (편심하중을 받는 박벽개단면 압축재의 임계하중)

  • 나영진;이수곤
    • Computational Structural Engineering
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    • v.9 no.4
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    • pp.135-140
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    • 1996
  • Single angle or channel with thin-walled open section can be used as compression member for example as web member in truss. In this case the inevitable eccentricity due to fabrication is commonly neglected in structural design. However eccentricity effect should be considered in the member design, especially in case of compression member. The critical loads of compression members that buckle by twisting or by a combination of bending and twisting are to be determined by solving governing differential equations. In this paper, the investigations are limited to the rolled channels([), equal-leg angles(L), lipped channels(C) and the applied loads are assumed to have some eccentricities.

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A Study on the Coating Fracture in Silicon Nitride Bilayer : II. Effect of Coating Thickness (질화규소 이층 층상재료에서 코팅층의 파괴에 관한 연구 : II Coating Thickness의 영향)

  • 이기성;이승건;김도경
    • Journal of the Korean Ceramic Society
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    • v.35 no.1
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    • pp.48-54
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    • 1998
  • The effect of coating thickness on the contact fracture was studied, in Si3N4 coated Si3N4-BN system When the elastic/plastic mismatch is relatively large betwen two layers in bilayer certain critical coating thickness was required to prevent cone crack initiation and this critical thickness was decreased by de-creasing the elastic/plastic mismatch,. In addition the required critical thickness should be increased when higher loads apply. In conclusion an appropriate coating thickness should be designed by elastic/plastic mismatch between two layers and environment (applied load) to prevent the coating fracture

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Experimental Study on the Stability of the Cantilever Beam with Tip Mass Subjected to a Follower Force (종동력을 받는 첨단질량을 갖는 외말보의 안전성에 관한 실험적 연구)

  • 노광춘;박영필
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.10 no.2
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    • pp.183-187
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    • 1986
  • An experimental method to give a tangential follower force to a cantilever beam having a concentrated tip mass by the magnetic force of the electromagnet has been described. The dynamic behaviour of the beam under this nonconservative load has been analysed by experimentally as well as by theoretically. The theoretical and experimental results on the natural frequencies and the critical force of the systems are in good agreement with each other.

A Study on Dynamic Stability Regions for Parabolic Shallow Arches (낮은 포물선(抛物線) 아치의 동적(動的) 안정영역(安定領域)에 관한 연구(硏究))

  • Park, Kwang Kyou;Kim, Moon Kyum;Hwang, Hak Joo
    • Journal of The Korean Society of Civil Engineers
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    • v.6 no.3
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    • pp.1-9
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    • 1986
  • Dynamic stability of parabolic shallow arches, which are supported by hinges at both ends, is investigated. The Runge-Kutta method is used to perform time integrations of the differential equations of motion with proper boundary conditions. Based on Budiansky-Roth criterion, dynamic critical load combinations are evaluated numerically for cases of step loads of infinite duration and impulse loads, individually. The results are plotted to get interaction curves. The loci of the dynamic critical loads, which are obtained in this study, are proposed as boundaries between the dynamic stability and instability regions for the parabolic shallow arches. The results for the parabolic shallow arches are also compared with those for sinusoidal arches of the same arch rises. According to the investigation, the dynamic stability regions for the parabolic arches are larger than those for the sinusoidal arches. However, it is shown that the arch rise is the more governing factor than the shape.

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A Numerical Study on Inplane Nonlinear Buckling Strengths of New Arches Subjected to Uniformly Distributed Loading (수직등분포하중을 받는 신형식단면 원형아치리브의 비선형 면내좌굴강도에 대한 해석연구)

  • Park, Jong-Sup;Kang, Sung-Young
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.1
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    • pp.399-405
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    • 2012
  • This paper investigates the characteristics of buckling loads for steel arches with new type cross section which is consisted of T-section and pipe-section. A general purpose finite-element program ABAQUS was used to evaluate the inelastic buckling strengths of the arches which included the influence of the geometric and material nonlinearity. According to the comparisons between earlier studies and results from finite-element analyses, new design equations should be developed for the new arches. New buckling factors were developed to consider influence of rise-to-span ratio and boundary conditions. It is found that the presented factors are sufficiently accurate to predict the inplane buckling loads of new type section steel arches subjected to uniformly distributed loading. The proposed equations can be used to investigate new type steel arches subjected to unsymmetrical loading and composited arches.

Characteristics of Buckling Load and Bifurcation in Accordance with Rise-span Ratio of Space Truss Considering Initial Imperfection (초기 불완전성을 고려한 공간 트러스의 분기좌굴과 라이즈-스팬 비에 따른 임계하중 특성)

  • Lee, Seung-Jae;Shon, Su-Deok
    • Journal of Korean Society of Steel Construction
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    • v.24 no.3
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    • pp.337-348
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    • 2012
  • This study investigated the characteristics of bifurcation and the instability due to the initial imperfection of the space truss, which is sensitive to the initial conditions, and the calculated buckling load by the analysis of Eigen-values and the determinant of tangential stiffness. A two-free nodes model, a star dome, and a three-ring dome model were selected as case studies in order to examine the unstable phenomenon due to the sensitivity to Eigen mode, and the influence of the rise-span ratio and the load parameter on the buckling load were analyzed. The sensitivity to the imperfection of the two-free nodes model changed the critical path after reaching the limit point through the bifurcation mode, and the buckling load level was reduced by the increase in the amount of imperfection. The two sensitive buckling patterns for the model can be explained by investigating the displaced position of the free node, and the asymmetric Eigen mode was a major influence on the unstable behavior due to the initial imperfection. The sensitive mode was similar to the in-extensional mechanism basis of the simplified model. Since the rise-span ratio was higher, the effect of local buckling is more prominent than the global buckling in the star dome, and bifurcation on the equilibrium path occurring as the value of the load parameter was higher. Additionally, the buckling load levels of the star dome and the three-ring model were about 50-70% and 80-90% of the limit point, respectively.

A Theoretical Study on Arching Effect of Embankment Pile Grid (격자배치 성토지지말뚝의 아칭효과에 대한 이론적 연구)

  • Lee, Seung-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.1
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    • pp.302-309
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    • 2017
  • The influence of the pile diameter, center to center pile spacing, internal friction angle of embankment soil, and height of embankment on the arching efficacy of the embankment pile was investigated. The arching efficacy, which was derived by the arch model developed in the embankment soil was calculated using two methods, one that considers crown failure of the arch and the other that considers load on the pile cap and critical relative spacing ratio for which the arching efficacy calculated by the two methods are the same. According to the computed results in this study, the arching efficacy calculated from a consideration of the load on pile cap governs when the relative spacing ratio becomes smaller and that calculated from the theory of crown failure governs when the relative spacing ratio becomes larger. The critical relative spacing ratio below which the arching efficacy calculated from a consideration of the load on pile cap governs the design decreases with increasing value, which is defined by the ratio of the pile diameter to the pile center to center spacing. Critical relative spacing ratios, which correspond to the values of 0.5 and 0.2 were 0.35 and 0.85, respectively. Considering the computed results, the critical relative spacing ratio decreases with increasing Rankine passive earth pressure coefficient and critical relative spacing ratios, which correspond to values of 5 and 2, were 0.23 and 0.85, respectively. The arching efficacy, which corresponds to the area ratio of 9%, was 54% and the one that corresponds to the value of 3 was 61%; the critical relative spacing ratios, which correspond to those arching efficacies, were greater than 0.5.

Classification system for figid and semi-rigid connection (강·반강 철골 접합부의 분류체계에 관한 연구)

  • Jang, Mee;Lee, Sang Sup;Mun, Tae Sup
    • Journal of Korean Society of Steel Construction
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    • v.13 no.4
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    • pp.351-361
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    • 2001
  • The connections are classified as rigid, semi+rigid, or pinned. There are two classification systems, EC3 adn Bjorhovede et al., representatively. The EC3 boundary between rigid and semi-rigid connections is in on the whole restrictive in term of the stiffness as well as the moment capacity of connections. The boundary specified by Bjorhovede et al. may not be sufficient to assure the behavior of rigid frames in some cases. In this study, it is proposed the new classification system for steel connection that depends on the reduction factor(R) of critical buckling load for unbraced semi-rigid frame expressed by the stiffness ratio($\rho$) of beam to column and the stiffness ratio(k) of connection to beam. Finally, it is examined by experimental data that new classification criteria provides a practical boundary compared wit hteh existing classifications.

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Elastic stability analysis of curved steel rib using differential quadrature method (DQM) (미분 구적법 (DQM)을 이용한 곡선 강지보의 안정성 해석)

  • Kang, Ki-Jun;Kim, Byeong-Sam;Kim, Sang-Hwan
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.6 no.4
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    • pp.279-290
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    • 2004
  • The differential quadrature method (DQM) for a system of coupled differential equations governing the elastic stability of thin-walled curved members is presented, and is applied to computation of the eigenvalues of out-of-plane buckling of curved beams subjected to uniformly distributed radial loads including a warping contribution. Critical loads with warping, which were found to be significant, are calculated for a single-span wide-flange beam with various end conditions, opening angles, and stiffness parameters. The results are compared with the exact methods available. New results are given for the case of both ends clamped and clamped-simply supported ends without comparison since no data are available The differential quadrature method gives good accuracy and stability compared with previous theoretical results.

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