• Title/Summary/Keyword: 미끄러짐 마찰

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Mechanical Characteristics of High Tension Bolted Joint Connections using Shear Ring (전단링을 사용한 고장력볼트 이음부의 역학적 특성에 관한 연구)

  • Lee, Seung Yong;Park, Young Hoon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.2A
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    • pp.327-338
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    • 2006
  • Friction type high tension bolted joints is one of the most common steel structure connections and requires significant concerns on axial force of the bolts. However, its high shear capacity is not appropriately considered in design and hence the number of bolts is over-designed than actually required. It is primarily due to a slip-load-based design method. This study, therefore, suggests a new technology of connection using a shear ring, which may reduce the shortcomings from the friction-typed high tension bolted joints and maximize the advantages from the bearing-typed joints. Experimental and numerical studies were performed to compare the capacity of the suggested method with traditional high tension bolted joints. From the results, it is known that the suggested connections has higher bearing capacity than friction-typed high tension bolted joints due to the higher shear resistance from the ring. For further study, it may be necessary to investigate on design parameters including the depth of shear ring, for increased connection capacity.

Experimental and Numerical Investigation of Sliding Response of Unconstrained Objects to Base Excitations (바닥진동에 의한 비구속 물체의 거동파악 실험과 수치해석 전산프로그램의 개발)

  • Lee, Sang Ho
    • The Journal of the Korea Contents Association
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    • v.14 no.3
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    • pp.463-469
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    • 2014
  • Safety related devices unconstrained temporally in the process of operation of nuclear power plants could be damaged by the sliding during seismic activity. In this study sliding response of unconstrained objects to the base excitations is studied experimentally and analytically. In experiments static and dynamic tests to determine the coefficient of friction and the shaking table experiments to verify the sliding response of the analytic results were conducted. Numerical solutions by solving the nonlinear differential equations of motion governing sliding were found by the computer program using the step by step acceleration method. The exact solutions of the sliding response to the simple forms of base excitations were found to verify the computer program developed in this study. Relative displacement envelopes were suggested as a colliding criteria of the unconstrained objects.

Geomechanical Stability Analysis of Potential Site for Domestic Pilot CCS Project (국내 이산화탄소 지중격리저장 실증실험 후보부지의 역학적 안정성 평가 기초해석)

  • Kim, A-Ram;Kim, Hyung-Mok;Kim, Hyun-Woo;Shinn, Young-Jae
    • Tunnel and Underground Space
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    • v.27 no.2
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    • pp.89-99
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    • 2017
  • For a successful performance of Carbon Capture Sequestration (CCS) projects, appropriate injection conditions should be designed to be optimized for site specific geological conditions. In this study, we built a simple 2-dimensional analysis model, based on the geology of Jang-gi basin which is one of the potential sites of domestic CCS projects. We evaluated the impact of initial stress conditions and injection rate through coupled TOUGH-FLAC simulator. From the preliminary analysis, we constructed risk scenarios with the higher potential of shear slip and performed scenario analysis. Our analysis showed that normal stress regime produced the highest potential of shear slip and stepwise increasing injection rate scenario resulted in much larger pore pressure build up and consequent higher potential of the shear slip, which was evaluated using a mobilized friction coefficient.

Effect of Transverse Reinforcement on the Shear Friction Capacity of Concrete Interfaces with Construction Joint (시공줄눈이 있는 콘크리트 경계면의 전단마찰 내력에 대한 보강철근의 영향)

  • Hwnag, Yong-Ha;Yang, Keun-Hyeok
    • Journal of the Korea Concrete Institute
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    • v.28 no.5
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    • pp.555-562
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    • 2016
  • The objective of the present study is to evaluate the shear transfer capacity of transverse reinforcement at the concrete interfaces with smooth construction joint. The transverse reinforcing bars were classified into two groups: V-type for the arrangement perpendicular to the interface and X-type for inclined-crossing arrangement. The transverse reinforcement ratio at the interface varied from 0.0045 to 0.0135 for V-type and 0.0064 to 0.0045 for X-type. The mechanism analysis proposed for monolithic concrete interface, derived based on the upper-bound theorem of concrete plasticity, was modified to evaluate the shear friction capacity of concrete interfaces with smooth construction joint. Test results showed that the specimens with X-type reinforcement had lower amount of relative slippage at the interface and higher shear friction capacity than the companion specimens with V-type reinforcement. This observation was independent of the unit weight of concrete. The mean and standard deviation of the ratios between the experimental shear friction strength of smooth construction joints and predictions obtained from the proposed model are 1.07 and 0.14, respectively.

Ultimate Behavior of High-Tension Bolted Joints Considering Plate Thickness and Bolt Size (판 두께와 볼트 크기를 고려한 고장력 볼트 이음부의 극한 거동)

  • Kim, Sung-Bo;Choi, Jong-Kyoung;Heo, In-Sung
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.21 no.5
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    • pp.515-524
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    • 2008
  • The ultimate behavior of high-tension bolted joints with various plate thickness and bolt size is investigated using nonlinear F.E. analysis and experimental study. The relation with sliding load, bolt deformation, and failure modes are presented based on plate thickness and bolt size. Three kinds of the bolt diameter(M20, M22, M24) and five types of the steel plates (l2mm, 16mm, 20mm, 30mm, 40mm) are considered for the ultimate behavior of the bolted joints. The numerical model, constructed by commercial F.E. program, ABAQUS, of ultimate behavior of bolted joints is introduced and verified by experimental results. The force-displacement and force-axial strain relations are measured and compared with the results by 3D finite element analysis.

A Study on Transient Chip Formation in Cutting with Self-Propelled Rotary Tools-Experimental Verification (자기추진 로타리 공구를 사용한 절삭에서 천이칩 형성에 관한 연구 - 실험에 의한 증명)

  • 최기흥;최기상;김정수
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.8
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    • pp.1910-1920
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    • 1993
  • An experimental study to investigate the unconventional chip formation called triangulation of chip in cutting with a SPRT (self-propelled rotary tool) is performed using acoustic emission (AE) signal analysis. In doing that, a quantitative model of the AE RMS signal in triangulation with a SPRT is first developed. The predicted results from this model show good correlation between the AE RMS signal and the general characteristics of triangular chip formation. Then, effects of various process parameters such as cutting conditions (cutting speed, depth of cut, oblique angle and normal rake angle) and the work material properties on the chip formation in cutting with a SPRT are explored. Special attention is paid to the work material properties which are found to have significant effects on triangulation.

Analysis of the Frictional Behavior of Rubber Block (고무 블록의 마찰 거동 해석)

  • Kim, Doo-Man;Yoo, Hyun-Seung
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.14 no.3
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    • pp.16-22
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    • 2006
  • The friction and wear of tire determined by frictional behavior of tire tread that translate driving force, cornering force and braking force between automobile and road as a result of frictional behavior of each tread block. The tire tread block is representative case of rubber block doing frictional behavior. In this paper, frictional behavior of rubber block under compressive force and shear force was analytically obtained by using slip starting position parameter instead of friction coefficient which is uncertain to express exact value between rubber and other surfaces yet. And local coefficients of friction were calculated as a function of compressive force, shear force, shear modulus of rubber, shape factor and slip starting position.

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Scenario Analysis of Injection Temperature and Injection Rate for Assessing the Geomechanical Stability of CCS (Carbon Capture and Sequestration) System (이산화탄소 격리저장시스템의 역학적 안정성 평가를 위한 주입온도 및 주입량 시나리오 해석)

  • Kim, A-Ram;Kim, Hyung-Mok
    • Tunnel and Underground Space
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    • v.26 no.1
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    • pp.12-23
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    • 2016
  • For a successful accomplishment of Carbon Capture Sequestration (CCS) projects, appropriate injection conditions should be designed and optimized for site specific geological conditions. In this study, we evaluated the effect of injection conditions such as injection temperature and injection rate on the geomechanical stability of CCS system in terms of TOUGH-FLAC simulator, which is one of the well-known T-H-M coupled analysis methods. The stability of the storage system was assessed by a shear slip potential of the pre-existing fractures both in a reservoir and caprock, expressed by mobilized friction angle and Mohr stress circle. We demonstrated that no tensile fracturing was induced even in the cold CO2 injection, where the injected CO2 temperature is much lower than that of the reservoir and tensile thermal stress is generated, but shear slip of the fractures in the reservoir may occur. We also conducted a scenario analysis by varying injected CO2 volume per unit time, and found out that it was when the injection rate was decreasing in a step-wise that showed the least potential of a shear slip.

Estimation of Safety and Economical Efficiency of Large High Tension Bolted Joints (대직경 고장력볼트 이음부의 안전성 및 경제성 평가)

  • Sung, Ki-Tae;Kyung, Kab-Soo;Lee, Seung-Yong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.13 no.6 s.58
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    • pp.97-105
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    • 2009
  • This study was conducted for the purpose of examinating the safety and economical efficiency of large high tension bolted joints. The specimen using F10T-M30 large high strength bolts has been selected and static tensile test has been conducted to evaluate the slip characteristics. In addition, finite element analysis has been carried out to estimate the number of required bolts. As a result, the average slip coefficient of M30 high strength bolts exceeded 0.4 - the standard in highway bridge design specification - and has satisfied the slip strength, which is the same as that of M22 high strength bolts. In addition, if F13T-M22 high strength bolts were applied, the number of required bolts decreased by 21%, and if F10T-M30 high strength bolts were applied, the number of required bolts decreased by 46%, that leads to the conclusion that the economical efficiency in accordance with diametering of high strength bolts was now verified.

A Study on the Mechanical Characteristics of High Tension Bolted Joints with Butt-Welded Joints (횡방향 맞대기 용접부를 가진 고장력볼트 마찰이음부의 역학적 특성에 관한 연구)

  • Chang, Dong Il;Kim, Hak Jae
    • Journal of Korean Society of Steel Construction
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    • v.10 no.1 s.34
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    • pp.101-113
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    • 1998
  • In this study, we research the influence of butt-welded joints in high tension bolted joints on the static and fatigue strength. As a results, if it's located inside or outside of the friction surface, the fatigue strength decrease, and the decrease of fatigue strength is greater in cases that the butt-welded joints exist outside of the friction surface. But the influence of butt-welded joint on the fatigue strength satisfies category B of the Specifications.

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