• Title/Summary/Keyword: 체결력

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Study on Fastened Properties by Applied to CFRP Laminates of Subminiature Screw (초소형나사의 CFRP 적층판 적용에 따른 체결특성에 관한 연구)

  • Choi, Byung Hui;Kim, Ho Joong;Kim, Ji Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.11
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    • pp.1239-1243
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    • 2014
  • This paper presents the application of carbon-fiber-reinforced polymer (CFRP) for the damage absorption and optimal design of portable smart devices to close in life. CFRP specimens are subjected to a tensile test to estimate their mechanical properties in terms of the stacking angles. Further, the screw reverse torque and screw torque at each stacking angle are determined using a torque tester after tapping holes on the CFRP specimens. Two experiments are performed for comparing their results in order to determine optimal conditions. In the tensile test, a woven specimen is found to have the highest strength and stiffness. In the case of the woven specimen, no difference is observed even when it is applied to prevent loosening of the coating. And average result value was excellent.

Application of Umbilical System for Launch Vehicle (우주 발사체 엄빌리칼 시스템의 현황 및 적용사례)

  • Kim, Dae Rae;Lim, Chankyoung
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.21-25
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    • 2017
  • The umbilical system used for launch vehicle is to connect all ground supply lines (Pneumatic, hydraulic and electrical) to launch vehicle and disconnect those at few second before launch vehicle lift-off (or simultaneously with launch vehicle lift-off). During launch preparation stage, all umbilical shall be securely connected and also at separation stage, separation of all umbilical line shall be guaranteed. Therefore finding an appropriate connection force is a key factor on development of umbilical system. According to these design requirement, various kind of umbilical system has been developed from early stage of space development till today. In this paper, various kind of umbilical system developed so far is introduced according to its feature and operational concept. Also, umbilical system used for KSLV-II is introduced

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An Evaluation of Structural Characteristics and Integrity for Rocket Motor Case according to Dome Types (돔 형상에 따른 연소관의 구조 특성 및 안전성 평가)

  • Ko, Hee-Young;Shin, Kwang-Bok;Kim, Won-Hoon;Koo, Song-Hoe
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.257-262
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    • 2009
  • Elastic-Plastic structural analysis was performed to evaluate structural characteristic and integrity for rocket motor case of solid propulsion system. The structural analyses were compared and evaluated using the simplified 2-D axisymmetric model and 3-D full model for rocket motor case with torispherical dome type. And pre-tension load for bolt model was considered in structural analysis. The results of displacement and stress for the simplified 2-D axisymmetric model and 3-D full model were in an good agreement with each other. Therefore, the simplified 2-D axisymmetric model for rocket motor case was recommended to verify quickly the structural integrity and save the modeling and calculating time in initial design stage. Also, the structural characteristic and integrity for rocket motor case according to 5 dome types was evaluated to select the optimal dome shape.

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A Study on the Improvement of Connection Method for Segment in Tunnel Lining System Using Prestressed Steel Cable by Real-scale Test (실대형 실험을 통한 쉴드터널의 강연선 체결방식에 대한 역학적 거동 분석)

  • Ma, Sang-Joon;Gil, Hu-Jeong;Kim, Dong-Min
    • Journal of the Korean Geotechnical Society
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    • v.29 no.6
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    • pp.33-51
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    • 2013
  • This paper introduces the improvement of connection method for segment in tunnel lining system using prestressed steel cable and presents the results of real-scale tests. It conducted a study about the applicability and mechanical behaviour analysis of the new method that connects segment tunnel lining using prestressed steel cable by real-scale test. Through the research, it was found that the new method has stronger connection than conventional assembling methods. Also, the new method can be expected to have integrated behavior and stability increase of shield tunnel lining. It is considered that the new method is much more effective than conventional assembling methods.

On Clamping Force Characteristics in M1.4 Subminiature Screw for CFRP Stacking Angles (M1.4 초소형 나사의 CFRP 적층 경향에 따른 체결력 특성에 관한 연구)

  • Kim, Jung Ho;Ra, Seung Woo;Kim, Hee Seong;Kim, Ji Hoon
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.6
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    • pp.517-521
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    • 2015
  • Recent development of core techniques the IT electronics industry can condense into lightweight and slimmer. In this circumstance, researches for the lightweight materials and subminiature screw have been attracted. In this study, the CFRP was produced by stacking angle to obtain the tensile properties. And Comparing the coated screws and non-coated screws on the specimen, and evaluating the adequacy for the application of CFRP using the result. So The clamping force measured by comparison evaluation. Low screw reverse and Superior torque value at each stacking angle were found the optimum conditions, when Subminiature Screw is applied on smart devices. Both tensile strength and stiffness of $[{\pm}0^{\circ}]_{10}$ is the highest. Followed by $[90^{\circ}/0^{\circ}]_{10}$ is the highest. The largest clamping torque is $[90^{\circ}/0^{\circ}]_{10}$ When Subminiature Screw is applied coating and non-coating to prevent loosening. Based on the above, Subminiature Screw should be applied in smart devices, because $[90^{\circ}/0^{\circ}]_{10}$ meet both tensile properties and clamping force.

The Study on Elongation and Torque Measurement in Large Bolt by using Ultrasonic Technology (초음파를 이용한 대형볼트 신장량 및 체결력 측정연구)

  • Ahn, Y.S.;Gil, D.S.;Park, S.G.
    • Journal of Power System Engineering
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    • v.13 no.3
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    • pp.40-46
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    • 2009
  • This study on the bolt elongation and torque measuring method by ultrasonic nod-destructive method. In the past, The dial gage was used for the elongation measurement of gas turbine bolts. The purpose of this study is to improve the traditional bolt elongation measurement method. The old method using dial gage measures the elongation of the gas turbine bolt. If the length differences among the loading bolts are within the required range, The loading torques of bolts consider as acceptable. But this method can not give the information about torque differences among the loading bolts. It could bring out vibration of turbine due to loading torque differences among the bolts. So the elongation and torque must be measured simultaneously. The new technology using ultrasonic non-destructive method can give the information about bolt elongation and torque. The ultrasonic method basically measures the speed in the bolt material for the calculation the bolt elongation. But the ultrasonic speed varies according to temperature and loading torque of bolts. So the factors of temperature and loading power were investigated and reflected to the calculation of bolt elongation and torque. The results of this study shows the big difference among the bolts torque in the old method and the torque differences among the bolts can be adjusted by reflecting the result of this study. And this torque adjusting method can decrease gas turbine vibration problem due to torque difference among the bolts. So this paper shows ultrasonic method is better than old method for the measurement of bolt elongation and torque.

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

  • 손승요;신근하
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.33-37
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    • 1994
  • When a bolt is tightened up to the range of plastic deformation, yielding is governed by the combined stresses due to the axial force developed in the bolt and the frictional torque developed on the thread in contact with the nut. Consideration is taken account of the fact that the unused portion of the thread has least sectional area being subject to initial yielding. Once yielding has taken place some strain hardening effect will 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 common and fine series thread are used for computational purposes. Variation of axial forces and frictional torques vs. the frictional coefficients tare presented together with other plots showing some characteristics of bolt under plastic deformation.

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Analysis for the Residual Stress by Cold Expansion Method and Interference Fit (흘확장법과 억지끼워맞춤에 의한 잔류응력 해석)

  • Jang, Jae-Soon;Yang, Won-Ho;Kim, Cheol
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.8
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    • pp.1615-1622
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    • 2002
  • The purpose of this study is comparing cold expansion method with interference fit. Cold expansion method and interference fit of fastener hole is using in the aerospace industry. These treatment lead to an improvement of fatigue life to the compressive residual stresses developed on the hole surface. But Research is nothing to about difference effect of between cold expansion method and interference fit. So, this paper, it is shown that Comparing cold expansion method with interference fit using the finite element method. It is further shown that residual stress distribution according to plate thickness and clamping force.

A Study of Bolt Tightening Changing Factor according to Durability Degradation (내구 열화에 따른 샤시계 볼트 체결력 변화 인자 연구)

  • Choi, Dong Young;Choi, Jae Chil;Han, Jong Uk
    • Journal of Auto-vehicle Safety Association
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    • v.7 no.1
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    • pp.20-26
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    • 2015
  • In vehicle development process, durability test should be carried out in field condition. Nowadays there are many customer live there multiple conditions. It makes change of the car's material. Such change causes to lose a bolt. Diversifications of climatic conditions are also a matter of loosening the bolt. To avoid this problem, to identify the cause of the problem, and the solution should be applied. To avoid problems during the durability development test should be measured by the clamping force. Ultrasonic instruments clamping force without affecting the torque can be measured. This instrument is part of the problem by monitoring the clamping force required to obtain objective data.

Precision Screw Driver utilizing a Bellows (벨로우즈방식의 정 밀 나사 체결기)

  • 정규원;오의진
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.10 no.5
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    • pp.53-59
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    • 2001
  • A screw driver is widely used in assembling machine parts or electronic products such as the printed circuit board with a housing. As the parts to be assembled becomes small and precise, the higher precision of the controlling screw driver torque is required. However, because the operator controls the fastening torque based on experience, it must be inexact and the setting procedure will be time consuming job. Thus the screw driver which can exactly control the fastening torque is developed utilizing a bellows in this paper. The bellows is expanded by the inner air pressure and contracted by the spring operation. The bellows type driver is composed of a clutch mechanism with two solenoid valves and a pressure sensor. Those valves are controlled using the detected bellows pressure by the sensor. When the pressure reaches the setting value, the exit solenoid valve is opened to release the air pressure from the bellows so as not to deliver further torque. Through a series of experiments, the performance is examined and verified.

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