• Title/Summary/Keyword: 체결력

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Strength Analysis of Composite Double-lap Bolted Joints by Progressive Failure Theory Based on Damage Variables (손상변수기반 점진적 파손이론을 이용한 복합재 이중 겹침 볼트 체결부의 강도 해석)

  • Kim, Sang-Kuk;Kweon, Jin-Hwe
    • Composites Research
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    • v.26 no.2
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    • pp.91-98
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    • 2013
  • A three-dimensional finite analysis method was proposed to predict the failure of composite double-lap bolted joints, which is based on the stiffness degradation method using damage variables and Hashin's three-dimensional failure criteria. Ladeveze's theory using damage variables to consider the matrix/shear damage was combined with stiffness degradation in fiber direction. Four different failure modes were considered including matrix compression/shear, matrix tension/shear, fiber compression, and tension failures. The friction between bolt and composite and the clamping force were considered using a commercial finite element software ABAQUS. The damage model was incorporated using the user-defined subroutine of the software. The predicted result was verified with the existing test result for bearing tension double shear and showed the deviation ranging 7~16% from test results.

A Study on Shoe Bonding Mechanism Considering Recycling (재활용을 고려한 신발 접착 메커니즘에 관한 연구)

  • Song, Hyun-Su;Moon, Kwang-Sup;Mok, Hak-Soo
    • Resources Recycling
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    • v.27 no.2
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    • pp.3-10
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    • 2018
  • In this paper, Proposed bonding mechanism that can separate sole and upper for recycle and reuse of parts. It was confirmed that the PVC film with better physical properties than the existing parts was inserted between the sole and the upper. It was confirmed that the separation of the desired form can be induced. As a result of checking the performance of the proposed mechanism, it is confirmed that intentional separation is possible and the separated sole and upper can be recycled or reused.

Study on the Clamping Force and the Friction Coefficient in a Bolt tightened up to the Plastic Range (소성역체결 볼트의 체결력과 마찰계수에 관한 연구)

  • 손승요;신근하
    • Computational Structural Engineering
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    • v.7 no.3
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    • pp.133-141
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    • 1994
  • When a bolt is tightened up to the range of plastic deformation, yielding may be governed by the combined stresses due to the axial force developed in the bolt and the frictional torque induced on the thread by the contact with the nut. Consideration is taken account of the fact that the unengaged portion of the thread has least sectional area, being subject to initial yielding. Once yielding has taken place some strain hardening effect may result. Incremental stress-strain relations are used to treat the continued yielding, which is equivalent to treat continued yielding as if summing up the effects of thin walled cylinders subject to plastic deformation. M10 bolts of fine threads are used for both computational and experimental purposes. Variation of axial forces and frictional torques vs. the frictional coefficients are presented together with other plots showing some characterist of bolt under plastic deformation. Finally, a design and control aid for the tightening(i.e., kind of nomograph) is presented, showing the relationships among the torque factor and frictional coefficients for that particular bolt used in the experiment.

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Tapered Joint Design for Power Transmission of MW-grade Wind Turbine (MW급 풍력발전기 동력전달용 테이퍼 연결장치 설계에 관한 연구)

  • Kang, JongHun;Bae, JunWoo;On, Hanyong;Kwon, Yongchul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.11
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    • pp.1183-1189
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    • 2015
  • This study focuses on the design of the tapered joints of a wind power turbine. The main variables of the tapered joint are the transmitted torque, shaft diameter, contact area of the tapered ring, and tightening torque of the bolts, which applies a compressive pressure from the hub to the shaft. The stress distribution of the taper fit was calculated under axisymmetric plane strain conditions because of the small taper angle. The axial displacement of the clamp can be calculated from the radial elastic deformation and the taper angle. The stress field of each ring is obtained from the cylinder stress equation. To verify the accuracy of the calculation, finite element (FE) analysis was performed, and the results of the calculation and FE analysis were compared. The hoop stress of the tapered surface showed a discrepancy of approximately 10, but the trends of the stress distributions of each component and the relative movement obtained by FE analysis were in good agreement with the analytical calculation results.

Evaluation on Clamping Force of High Strength Bolts By Coating Parameters of Faying Surfaces (고력볼트 접합부표면의 방식도장변수에 따른 체결력 평가)

  • Nah, Hwan Seon;Lee, Hyeon Ju
    • Corrosion Science and Technology
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    • v.11 no.2
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    • pp.48-55
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    • 2012
  • Clamping force of a high strength bolt is reduced by a certain period of time after the initial set-up. In case of special treatments on faying surfaces such as protective coating, clamping force is relaxed more severely. Tests for slip critical joints subject to various faying surface parameters were conducted. Five different surface treatments were tested including mill scale surface, blast surface, rust surface and coated surfaces. Each specimen was composed of F10T M20 of high strength bolts and steel plates. Based on the result of slip coefficient test, blast treatment surface showed 0.59, rust treatment surface showed 0.54 and inorganic zinc treatment surface exhibited 0.44. Clean mill treatment surface and red lead paint treatment surface were 0.23, 0.21 respectively. It is identified that the slip coefficient in Korean structural design guide should be determined for various surface conditions. Subsequently from long term relaxation test of ASTM A 490 high strength bolts, relaxation of no-coated surfaces such as blast, clean mill, rust treatment, the loss of initial clamping load was 10.5%, 13.6% and 7.9% for 1,000 hours, while the loss of initial clamping force was reached as 15.0%, 18.7% more than the required redundancy 10% in case of inorganic zinc and red lead painted treatment. It is required that the limit of relaxation on coated faying surface should be established separately for various surfaces.

Investigation of Fastening Performance of Subminiature Serrated Bolt (초소형 쎄레이션 볼트의 체결성능 분석)

  • Jang, Myung Guen;Jeong, Jin Hwan;Jang, Yeon Hui;Kim, Hee Cheol;Kim, Jong-Bong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.4
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    • pp.257-262
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    • 2017
  • As the size of electric products such as mobile phones and smart watches decrease, the bolts used to assemble these products should also be miniaturized. A miniature-sized bolt has to provide sufficient joining torque and anti-releasing torque to keep the components together. We studied a serrated bolt as a candidate for a miniature-sized fastener to increase the anti-releasing torque. In a serrated bolt, a serrated shape is formed on the bottom surface of the bolt head to create an obstacle to releasing. In this study, finite element analyses for the joining and releasing of bolts were carried out, and the anti-releasing performance was predicted. Based on the results of analyses using various numbers of serrations and fastening depths, the effects of the number of serrations and fastening depth on the anti-releasing performance were investigated.

Development and Benchmark Test of Hole-Boss Locking Washers for the Prevention of Vibrational Loosening (나사 풀림 방지를 위한 걸림턱 구조의 와셔 개발 및 성능 비교)

  • Oh, Young-Tak;Kim, Gi-Dae
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.8
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    • pp.28-34
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    • 2020
  • In this study, hole-boss locking washers were developed to prevent vibrational loosening, and a benchmark test was conducted to compare these washers with existing wedge locking washers, which are imported and high-priced. The developed washers consist of an upper washer with bosses and a lower washer with holes, and the bosses are caught in the holes so that the bolt is not loosened. Additionally, the top side of the upper washer and the underside of the lower washer have small wedges perpendicular to the direction of the bolt loosening, suppressing slips. A test by the Korea Test Laboratory indicated that the ratio of the loosening torque to the joining torque is greater than 70%, confirming that the developed washers have a sufficiently high anti-loosening performance. A Junker test apparatus was manufactured for the testing of vibrational loosening and a test comparison between the proposed washers and the existing wedge locking washers shows that the proposed washers have a slower reduction in the clamping force and a higher loosening-resistance in a vibrational circumstance compared with the wedge locking washers. These results indicate that the developed washers demonstrate a high performance and boast price competitiveness.

Finite Element Analysis of Concrete Railway Sleeper Damaged by Freezing Force of Water Penetrated into the Inserts (고속철도 콘크리트 궤도 매립전 내 침투수의 결빙압에 의한 균열손상해석)

  • Moon, Do-Young;Zi, Goang-Seup;Kim, Jin-Gyun;Jang, Seung-Yup
    • Journal of the Korean Society for Railway
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    • v.14 no.3
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    • pp.240-247
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    • 2011
  • Finite element analysis was undertaken to investigate the effect of freezing force of water unexpectedly penetrated into inserts used in railway sleeper on pullout capacity of anchor bolts for fixing base-plate onto concrete sleeper. Based on the in-situ investigation and measurement of geometry of railway sleeper and rail-fastener, the railway sleeper was modeled by 3D solid elements. Nonlinear and fracture properties for the finite element model were assumed according to CEB-FIP 1990 model code. And the pullout maximum load of anchor bolt obtained from the model developed was compared with experimental pullout maximum load presented by KRRI for verification of the model. Using this model, the effect of position of anchor bolt, amount of fastening force applied to the anchor bolt, and compressive strength of concrete on pull-out capacity of anchor bolts installed in railway sleeper was investigated. As a result, it is found that concrete railway sleepers could be damaged by the pressure due to freezing of water penetrated into inserts. And the pullout capacity of anchor bolt close to center of railway is slightly greater than that of the others.

Prediction of Joining Torque for Bit Depth of Subminiature Bolt (초소형 볼트의 비트 깊이에 따른 체결 토크 예측)

  • Lee, Hyun-Kyu;Park, Keun;Ra, Seung-Woo;Kim, Jong-Bong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.8
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    • pp.917-923
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    • 2014
  • Subminiature joining bolts are required for the electronic parts of gadgets such as mobile phones and watch phones. During the miniaturization of bolt heads, it is difficult to obtain sufficient joining force owing to the risk of shear fracture of the bolt head or severe plastic deformation on the bit region. In this study, the maximum joining torque for the bit depth was predicted using finite element analysis. A shear fracture test was conducted on a wire used in bolt forming. The results of this test were subjected to finite element analysis and a fracture criterion was obtained by comparing the experimental and analysis results. The shear fracture of the bolt head during joining was predicted based on the obtained criterion. Furthermore, the maximum joining torque was predicted for various bit depths. Fracture on the boundary between the bolt head and thread was found to occur in lower joining torque as bit depth increases.

Performance Verification of Hinge Driving Segmented Nut Type Holding and Release Mechanism for Cube Satellite Applications (큐브위성용 힌지 구동형 분리너트식 구속분리장치의 실험적 성능검증)

  • Oh, Hyun-Ung;Lee, Myeong-Jae
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.42 no.6
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    • pp.529-534
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    • 2014
  • Pyrotechnic devices are widely used for space appendages. However, a cube satellite requirements do not permit the use of explosive pyrotechnic device. A nichrome burn wire release has typically been used for holding and release of deployable appendages of the cube satellite due to its simplicity and low cost. However, relatively low mechanical constraint force and system complexity for application of multi-deployable systems are disadvantages of the conventional mechanism. To overcome these drawbacks, we developed a hinge driving segmented nut type holding and release mechanism based on the nichrome burn wire release. The functional performance of the mechanism has been verified through release function test, static load test and shock level measurement test.