• Title/Summary/Keyword: 체결력

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Finite Element Analysis of Residual Stress by Cold Expansion Method with Clamping Force in the Plate having Adjacent Holes (인접홀에서 홀확장법과 체결력 고려시, 발생하는 잔류응력 분포에 대한 유한요소해석)

  • Yang Won-Ho;Cho Myoung-Rae;Jang Jae-Soon
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.5
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    • pp.149-154
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    • 2006
  • The cold expansion method (CEM) is one of the widely used a method to improve the fatigue behavior of materials in aerospace industry. Such improvement is due to the compressive residual stress developed when a tapered mandrel goes through the fastener holes a little smaller than the mandrel. CEM is retarded of crack initiation due to the compressive residual stress developed on the hole surface. Many researchers are studied a finite element analysis of residual stress around fastener hole. But in case of real model, fastener hole has a clamping force after CE. Therefore, it is respected that residual stress distributions should be changed due to clamping forces. In this paper, it was performed finite element analysis of residual stress by clamping force after CE in the plate having adjacent holes. From this study, it has been found that compressive residual stress near the hole increases according to clamping force. Also, the more increase clamping force, the more increases compressive residual stress. However, tensile residual stress increase beyond clamping force area.

A Study on the Clamping Force of an Automotive Air-conditioning Hose according to the Friction Coefficient (마찰계수를 고려한 자동차용 에어컨 호스의 체결력에 관한 연구)

  • Baek, Jae-Kwon;Kim, Byung-Tak
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.10 no.3
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    • pp.39-46
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    • 2011
  • The automotive air conditioning hose is used for connecting the components of air conditioner in a vehicle. The hose is usually manufactured by the swaging process to connect the rubber hose with the metal fitting at the end of the hose. In case that the clamping force is small, the refrigerant gas in the hose can leak locally under the severe operating circumstances. The practical test of clamping force is performed by means of the measurement of separation force. In this study, the swaging process of a hose is simulated with the finite element method, to investigate the effect of friction coefficient on the clamping force. The contact condition is used in consideration of real manufacturing process, and the material properties for the Mooney-Rivlin model is obtained by the experimental results. The result interpretations are focused on the contact forces, which is displayed graphically with respect to friction coefficient, on the surfaces between the hose and the metal fittings.

A Study on the Clamping Improvement of Precision Screws according to the Materials and Thread Changes (소재와 나사산 변화에 따른 정밀나사의 체결력 향상에 관한 연구)

  • Hwang, Woo Chae;Ra, Seung Woo
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.6
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    • pp.503-507
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    • 2015
  • In this study, we compare the performance of the screw through the Clamping force of the test materials to change shape and structure, one of the ways to maintain and improve the engaging force to cope with the miniaturization of the fastener threads are further thinner and lighter precision way that can improve the fastening force of the screw results were as follows. The clamping force according to the materials was $7.57N{\cdot}cm$ in SUS XM7 and SWCH18A was $5.97N{\cdot}cm$. This result was to be found to average 13.5% high in the Clamping force of SUS XM7 materials. In the case of the clamping force of the screw thread shape change, the clamping force of symmetrical and asymmetrical thread was $6.78N{\cdot}cm$ and $7.57N{\cdot}cm$. The clamping force of the asymmetrical thread showed an average high of 11.6%.

Study on the Profile of Nut Bearing Surface and the Torque Coefficient of a High Strength Bolt Set (고장력 볼트세트의 자리면형상과 토크계수에 관한 연구)

  • Lee, Baek Joon;Sohn, Seung Yo
    • Journal of Korean Society of Steel Construction
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    • v.12 no.2
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    • pp.143-150
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    • 2000
  • Depending upon the combination of tolerances specified in the standards on bolt, nut and washer for high tension bolt sets, there arises center-to-center deviation between bolt and washer. This deviation nay cause loss of effective contact area between nut- and washer-faces, which leads to some dispersion of the torque coefficient K. By adapting circular arc surface instead of flat surface for the nut, it is shown through numerical analyses that the dispersion of the torque coefficient can be minimized. In this way, optimum radius of curvature of the nut bearing surface is proposed.

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Loosening behavior of Internal and External Connection Dental Implants under Cyclic Loads Considering Pre-fastening Force (체결력을 고려한 내부 및 외부연결형 임플란트의 반복 하중에 대한 풀림 연구)

  • Lee, Yongwoo;Jang, Yong Hoon
    • Tribology and Lubricants
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    • v.37 no.4
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    • pp.136-143
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    • 2021
  • This paper presents the loosening behavior that occurs after the application of an external load to internal and external connection types of dental implants using the finite element method. We use fastening force between an abutment and a fixture to clamp the dental implant system; however, loosening and breakage may occur owing to cyclic external loads. In this study, we considered the initial fastening condition in the pre-load analysis and then investigated the change in stress and contact surface status when applying external loads. After the application of the initial fastening load, we verified that the internal connection-type model exhibited a relatively lower stress distribution than that of the external connection-type one. Moreover, we found that the former model showed a lower stress concentration after the application of the external load. In addition, after the application of this load, we found that the higher the shear load acting on the implant system, the higher the possibility of loosening. The study results showed the change in stress distribution and contact surface according to the connection type of the dental implants and the phenomenon of loosening by cyclic loads. We expect that the results of this study will be useful for the study of reliability and design of dental implant systems.

A Study on the Development of New Rail Fastening Devices (철도레일체결장치의 국내 독자모델 개발에 관한 연구)

  • Kwon, Tae-Soo;Cho, Yong-Hyeon
    • Proceedings of the KSME Conference
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    • pp.819-824
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    • 2001
  • Most of rail fastening system used in the interior have depended on the foreign technologies. In this study, new rail fastening device is developed to estabilish the domestic technology. Especially, Pandrol and Vossloh rail fastening devices are analyzed to utilize the weak and strong points. New rail fastening device is designed to combine advantages of two other foreign devices.

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A Study on Constitution of Plant Safety Inspection System for Measuring Joint Axial Force of High Tension Bolt (고장력 볼트의 체결축력 측정을 위한 설비 안전 검사 시스템 구축에 관한 연구)

  • Kim, J.Y.;Park, S.G.;Kim, H.S.;Kim, C.H.;You, S.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.15 no.2
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    • pp.371-377
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    • 1995
  • By using ultrasonic waves, we obtained conclusion from the experiment for measuring joint axial force of high tension bolt. The conclusion is followed. : From the high tension bolts used at turbine of Thermoelectric Power Plant, we obtained the equation of calculating joint axial force that is ${\sigma}=\frac{{\Delta}BPD}{j{\times}{\Sigma}{\delta}}$. By using IBM PC, which is inputed by the equation for calculating joint axial force of high tension bolts, we got joint axial force of high tension bolts form beam path of ultrasonic waves. Furrther, we can identify that constitution of plant safety inspection system is possible.

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