• 제목/요약/키워드: plastic bending moment

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인공발(Prosthetic Foot) 스프링용 유리섬유강화 적층재의 적층배향에 따른 층간분리거동 해석 (Analysis of Delamination Behavior on the Stacking Sequence of Prosthetic Foot Keel in Glass fiber Reinforced Laminates)

  • 송삼홍;김철웅
    • 대한기계학회논문집A
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    • 제27권4호
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    • pp.623-631
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    • 2003
  • It is considered that the application of advanced composite materials to the prostheses for the disables is important to improve their bio-mechanical performance. Particularly, energy storing foot prosthesis is mostly important to restore gait ability of the disables with low-extremity amputation since it could provide propulsion at terminal stance enhancing the disables ability to walk long distance even run and jump. Therefore, the energy storing spring of Prosthetic foot keel under cyclic bending moment use mainly of high strength glass fiber reinforced plastic. The main objective of this study was to evaluate the stacking sequence effect using the delamination growth rate(dA$_{D}$/dN) of energy storing spring in glass fiber reinforced plastic under cyclic bending moment. The test results indicated that the shape of delamination zone depends on stacking sequence in GFRP laminates. Delamination area(A$_{D}$) turns out that variable types with the contour increased non-linearly toward the damage zones.nes.

무아레 간섭계를 이용한 WB-PBGA 패키지의 온도변화 및 굽힘하중에 대한 거동해석 (Thermo-mechanical and Flexural Analysis of WB-PBGA Package Using Moire Interferometry)

  • ;주진원
    • 대한기계학회논문집A
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    • 제26권7호
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    • pp.1302-1308
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    • 2002
  • Thermo-mechanical and flexural behavior of a wire-bond plastic ball grid array (WB-PBGA) package are characterized by high sensitive moire interferometry. Moire fringe patterns are recorded and analyzed for several bending loads and temperatures. At the temperature higher than $100^{\circ}C$, the inelastic deformation in solder balls become more dominant, so that the bending of the molding compound decreases while temperature increases. The deformation caused by thermally induced bending is compared with that caused by mechanical bending. The strain results show that the solder ball located at the edge of the chip has largest shear strain by the thermal load while the maximum average shear strain by the bending moment occurs in the end solder.

Comments on a Case Study on Engineering Failure Analysis of Link Chain

  • Yu, George Y.H.
    • Safety and Health at Work
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    • 제12권4호
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    • pp.544-545
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    • 2021
  • The article by Tae-Gu Kim et al. conducted elastic FE modeling, which was inappropriate for fracture of elastic-plastic chain material (11.3% of elongation). FE analysis results and the findings in the fracto-graphic analysis did not tally but contradicted each other. The article identified "incorrect installation"/bending forces as the root cause while FE results of the chain under bending forces showed very low stresses at fracture locations but the highest stress in the middle of shank of the chain. The article's "step-like topographies indicating the fracture due to bending moment rather than uniaxial tension" lacked scientific support. The load value carried by each chain section under bending/incorrect installation was only half of that under tension, thus the article using same load value in FE simulation comparison for bending and tension was incorrect. The real cause of the chain fracture was likely improper checking the lifted load or/and using the wrong chain with much lower safety working load.

Analysis on Short Crack Growth Rate after Single Overload under Cyclic Bending Moment

  • Song, Sam-Hong;Lee, Kyeong-Ro;Kim, Amkee
    • International Journal of Precision Engineering and Manufacturing
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    • 제2권3호
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    • pp.19-26
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    • 2001
  • In order to investigate the effect of single tensile overload on the short crack growth behavior under the out-of-plane cyclic bending moment, crack opening stresses were continuously measured by an elastic compliance method using strain gages. The characteristics of short crack growth after the single tensile overload are analyzed by the effective stress range ratio. Futhermore, the investigation was carried out with respect to various fatigue crack growth behaviors such as the plastic zone size effect on crack retardation, the retarded crack length and the number of cycles.

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노치형태 변화에 따른 Al/AFRP 적층재의 층간분리거동 (Variation of Notch Shape on the Delamination Zone Behavior in Al/AFRP Laminates)

  • 송삼홍;김철웅
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 추계학술대회논문집A
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    • pp.278-285
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    • 2001
  • Aluminum/Aramid Fiber Reinforced Plastic(Al/AFRP) laminates are applied to the fuselage-wing intersection. The main objective of this study was to evaluate the delamination zone behavior of Al/AFRP with a saw-cut and circular hole using average stress criterion and the effect of notch geometry. Mechanical tests were carried out to determine the cyclic-bending moment and delamination zone observed ultrasonic C-scan pictures. In case of Al/AFRP containing saw-cut specimen, the shape and size of the delamination zone formed along the fatigue crack. However, in case of Al/AFRP containing circular hole specimen, the shape and size of delamination zone formed two types. first type, delamination zone formed along the fatigue crack. Second type, not observed fatigue crack. Therefore, delamination zone was formed dependently of the circular hole shape.

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Experimental and numerical studies on cyclic behavior of continuous-tenon joints in column-and-tie timber construction

  • Qi, Liangjie;Xue, Jianyang;Xu, Dan
    • Structural Engineering and Mechanics
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    • 제75권5호
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    • pp.529-540
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    • 2020
  • The mechanical properties of timber construction have drawn more attention after the 2013 Lushan earthquake. A strong desire to preserve this ancient architectural styles has sprung up in recent years, especially for residential buildings of the mountainous areas. In the column-and-tie timber construction, continuous-tenon joints are the most common structural form to connect the chuanfang (similar to the beam in conventional structures) and the column. To study the cyclic performance of the continuous-tenon joints in column-and-tie timber construction, the reversed lateral cyclic loading tests were carried out on three 3/4 scale specimens with different section heights of the chuanfang. The mechanical behavior was assessed by studying the ultimate bending capacity, deformation ductility and energy dissipation capacity. Test results showed that the slippage of chuanfang occurred when the specimens entered the plastic stage, and the slippage degree increased with the increase of the section height of chuanfang. An obvious plastic deformation of the chuanfang occurred due to the mutual squeezing between the column and chuanfang. A significant pinching was observed on the bending moment-rotation curves, and it was more pronounced as the section height of chuanfang increased. The further numerical investigations showed that the flexural capacity and initial stiffness of the continuous-tenon joints increased with the increase of friction coefficient between the chuanfang and the column, and a more obvious increasing of bending moment occurred after the material yielding. The compressive strength perpendicular to grain of the material played a more significant role in the ultimate bending capacity of continuous-tenon joints than the compressive strength parallel to grain.

플라스틱 온실의 강관 이음부 휨성능 분석 (Evaluation of Steel-Pipe Connections in Plastic Greenhouse Using Bending Test)

  • 최만권;류희룡;조명환;유인호
    • 생물환경조절학회지
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    • 제27권4호
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    • pp.391-399
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    • 2018
  • 본 연구에서는 현장에서 사용되는 온실 강관의 이음 방법에 대해 휨성능을 평가하고 그 결과를 바탕으로 가장 휨성능이 우수한 이음 방법을 알아보았다. 실험 결과, 모든 실험체는 이음이 없는 실험체 보다 휨성능이 작았다. 그러나 모든 실험체의 최대 휨모멘트는 이음이 없는 실험체 소성모멘트의 1.07~1.3정도로 나타났다. 또한 연결방법에 따른 결과는 연결핀 보다 인발 실험체가 상대적으로 큰 휨성능을 보였다. 현장 이음 방법의 파괴 모드는 연결핀과 강관 끝부분의 응력집중에 의한 국부좌굴이 지배적이었다. 현장시공 시 강관을 절단 후 연결할 경우, 이음 없이 사용하는 것이 가장 우수한 휨성능을 발휘하지만 부득이 강관을 절단할 경우는 연결핀보다는 인발 강관에 직결나사로 고정한 이음 방법(SPJ-F)으로 시공하는 것이 유리할 것으로 판단된다.

Progressive collapse analysis of steel frame structure based on the energy principle

  • Chen, Chang Hong;Zhu, Yan Fei;Yao, Yao;Huang, Ying
    • Steel and Composite Structures
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    • 제21권3호
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    • pp.553-571
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    • 2016
  • The progressive collapse potential of steel moment framed structures due to abrupt removal of a column is investigated based on the energy principle. Based on the changes of component's internal energy, this paper analyzes structural member's sensitivity to abrupt removal of a column to determine a sub-structure resisting progressive collapse. An energy-based structural damage index is defined to judge whether progressive collapse occurs in a structure. Then, a simplified beam damage model is proposed to analyze the energies absorbed and dissipated by structural beams at large deflections, and a simplified modified plastic hinges model is developed to consider catenary action in beams. In addition, the correlation between bending moment and axial force in a beam during the whole deformation development process is analyzed and modified, which shows good agreement with the experimental results.

Behaviour of flush end-plate beam-to-column joints under bending and axial force

  • da Silva, Luis Simoes;de Lima, Luciano R.O.;da S. Vellasco, Pedro C.G.;de Andrade, Sebastiao A.L.
    • Steel and Composite Structures
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    • 제4권2호
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    • pp.77-94
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    • 2004
  • Steel beam-to-column joints are often subjected to a combination of bending and axial forces. The level of axial forces in the joint may be significant, typical of pitched-roof portal frames, sway frames or frames with incomplete floors. Current specifications for steel joints do not take into account the presence of axial forces (tension and/or compression) in the joints. A single empirical limitation of 10% of the beam's plastic axial capacity is the only enforced provision in Annex J of Eurocode 3. The objective of the present paper is to describe some experimental and numerical work carried out at the University of Coimbra to try to extend the philosophy of the component method to deal with the combined action bending moment and axial force.

굽힘 하중이 작용하는 비대칭노치시편의 완전소성해석 (Fully Plastic Analyses of Unequally Notched Specimens in Bending Moment)

  • 오창균;박진무;김윤재
    • 대한기계학회논문집A
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    • 제30권3호
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    • pp.269-278
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    • 2006
  • This paper proposes slip line fields for bending of unequally notched specimens in plane strain that have a sharp crack in one side and a sharp V-notch in the other side. Depending on the back angle, two slip line fields are proposed, from which the limit moment and crack tip stress fields are obtained as a function of the back angle. Excellent agreement between slip line field solutions with those from detailed finite element limit analysis based on non-hardening plasticity provides confidence in the proposed slip line fields. One interesting point is that, for the unequally notched specimen, the difference between the crack tip triaxial stress for tension and that for bending increases significantly with increasing the back angle. This suggests that such a specimen could be potentially useful to investigate the crack tip constraint effect on fracture toughness of materials. In this respect, the possibility of designing a new toughness testing specimen with varying crack tip constraint is discussed.