• Title/Summary/Keyword: 체결력

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Energy Dissipation Capacity of the T-stub Fastened by SMA bars (SMA 강봉으로 체결된 T-stub의 에너지소산능력)

  • Yang, Jae Guen;Baek, Min Chang;Lee, Jae Yun;Lee, Hyung Dong
    • Journal of Korean Society of Steel Construction
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    • v.26 no.3
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    • pp.231-240
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    • 2014
  • The T-stub subjected to an axial tensile force shows various behavior characteristics according to the changes in the diameter and tightening force of the fastener, the geometric shape of the T-stub, and the material properties of the T-stub and fastener. Due to the influence of these changes, the T-stub shows three failure modes: plastic failure after the flexural yielding of the T-stub flange, flexural yielding of the T-stub fillet, and fracture of the fastener. In general, a T-stub with a thin flange and where the gauge distance of the fastener is long has a larger energy dissipation capacity than a T-stub with a thick flange and where the gauge distance of the fastener is short, due to the plastic deformation after flexural yielding. In this study, three-dimensional nonlinear finite element analysis was carried out to determine the effect of the fastener used for fastening the T-stub on the energy dissipation capacity of the T-stub. For the fastener of the T-stub analysis model, F10T-M20 high-tension bolts and ${\varnothing}19.05-mm$ (3/4-inch) SMA bars were modeled, and the geometric shape of the T-stub was selected to represent the flexural yielding of the T-stub fillet and the axial tensile failure of the fastener.

A Study on the Weight-Reduction Design of High-Speed Maglev Carbody made of Aluminum Extrusion and Sandwich Composite Roof (알루미늄 압출재와 샌드위치 복합재 루프를 적용한 초고속 자기부상 열차의 차체 경량화 설계 연구)

  • Kang, SeungGu;Shin, KwangBok;Park, KeeJun;Lee, EunKyu;Yoon, IllRo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.10
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    • pp.1093-1100
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    • 2014
  • The purpose of this paper is to suggest a weight-reduction design method for the hybrid carbody of a high-speed maglev train that uses aluminum extrusion profiles and sandwich composites. A sandwich composite was used on the roof as a secondary member to minimize the weight. In order to assemble the sandwich composite roof and aluminum extrusion side frame of the carbody using welding, a guide aluminum frame located at the four sides of the sandwich composite roof was introduced in this study. The clamping force of this guide aluminum frame was verified by three-point bending test. The structural integrity and crashworthiness of the hybrid carbody of a high-speed maglev train were evaluated and verified according to the Korean Railway Safety Law using a commercial finite element analysis program. The results showed that the hybrid carbody composed of aluminum extrusion frames and a sandwich composite roof was lighter in weight than a carbody made only of aluminum extrusion profiles and had better structural performance.

Evaluation on Clamping force of High Strength Bolts By Temperature Parameter (온도변수에 따른 고력볼트 체결력 평가)

  • Nah, Hwan Seon;Lee, Hyeon Ju;Kim, Kang Seok;Kim, Jin Ho;Kim, Woo Bum
    • Journal of Korean Society of Steel Construction
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    • v.20 no.3
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    • pp.399-407
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    • 2008
  • The clamping of torque shear bolt is based on KS B 2819. It was misunderstood that the tension force of the TS bolt was induced generally at the break of pin-tail specified. However, the clamping forces on slip critical connections do not often meet the intended tension, as it considerably varies due to torque coefficient dependent on temperature variables despite the break of the pin tail. In this study, the tension of torque shear bolts were compared with two types of high-strength hexagon bolts by temperature parameters from ${-10^{\circ}C}$ to ${50^{\circ}C}$. Torque shear bolts showed that the average clamping force increased to 20kN as the temperature increased. In case of galvanized high-strength hexagon bolts, the average clamping forces at $0^{\circ}C$, $20^{\circ}C$, $50^{\circ}C$ were recorded over standard bolt tension, 178kN, and the worst standard deviation was 50kN. In case of high-strength hexagon bolts, ave rage clamping forces increased as the temperature went up, and the worst standard deviation was 33kN lower than that of galvanized high-strength hexagon bolts. As for the turn-of-the-nut method, at nut rotation of ${90^{\circ}}$, two types of high-strength hexagon bolts did not met the intended design bolt in tension, 162kN.it is neccessary to re-evaluate the range of turn of nut, ${120^{\circ}{\pm}30^{\circ}}$.

A Preliminary Drop Test of a Type IP-2 Transport Package with a Bolted Lid Type (볼트체결방식의 IP-2형 운반용기의 낙하예비시험)

  • Kim Dong-Hak;Seo Ki-seog;Park Hong Yun;Lee Kyung Ho;Yoon Jeong-Hyoun;Lee Heung-Young
    • Proceedings of the Korean Radioactive Waste Society Conference
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    • pp.339-347
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    • 2005
  • A type IP-2 transport package should prevent a loss or dispersal of the radioactive contents and a more than $20\%$ increase in the maximum radiation level at any external surface of the package when it were subjected to the drop test under the normal conditions of transport. If a shielding thickness of IP-2 transport package is thick, a bolted lid type may prevent a loss or dispersal of the radioactive contents than the door type of ISO containers which are generally used as a type IP-2 transport package. In this paper, to evaluate the effect of drop directions on the bolt tension and the coherence of a bolt, the drop tests of preliminary small model are tested and evaluated for seven directions before the drop test of a type IP-2 transport package with a bolted lid type under the normal conditions of transport. Seven drop directions which are a bottom-vertical drop, a lid-vortical drop. a horizontal drop and four corner drops have been carried out. Using a force sensor, the bolt tension during the drop impact is measured. The coherence of bolt is evaluated by the difference between the fastening torque of bolt before a drop test and the unfastening torque of bolt after a drop impact.

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A finite element stress analysis on the supporting bone and abutment screw by tightening torque of dental implant abutment screw (치과용 임플란트 지대주나사의 조임체결력에 따른 지지골과 지대주나사의 유한요소법 응력 분석)

  • Lee, Myung-Kon
    • Journal of Technologic Dentistry
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    • v.42 no.2
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    • pp.99-105
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    • 2020
  • Purpose: A study analysed the stress distribution of abutment screw and supporting bone of fixture by the tightening torque force of the abutment screw within clinical treatment situation for the stability of the dental implant prosthesis. Methods: The finite element analysis was targeted to the mandibular molar crown model, and the implant was internal type 4.0 mm diameter, 10.0 mm length fixture and abutment screw and supporting bone. The occlusal surface was modeled in 4 cusps and loaded 100 N to the buccal cusps. The connection between the abutment and the fixture was achieved by combining three abutment tightening torque forces of 20, 25, and 30 Ncm. Results: The results showed that the maximum stress value of the supporting bone was found in the buccal cortical bone region of the fixture in all models. The von Mises stress value of each model showed 184.5 MPa at the 20 Ncm model, 195.3 MPa in the 25 Ncm model, and 216.5 MPa in the 30 Ncm model. The contact stress between the abutment and the abutment screw showed the stress value in the 20 Ncm model was 201.2 MPa, and the 245.5 MPa in the 25 Ncm model and 314.0 MPa in the 30 Ncm model. Conclusion: The increase of tightening force within the clinical range of the abutment screw of the implant dental prosthesis was found to have no problem with the stability of the supporting bone and the abutment screw.

Evaluation of Stress Reduction of Continuous Welded Rail of Sliding Slab Track from Track-Bridge Interaction Analysis (궤도-교량 상호작용 해석에 의한 슬라이딩 슬래브 궤도의 장대레일 응력 저감 효과 분석)

  • Lee, Kyoung Chan;Jang, Seung Yup;Jung, Dong-Ki;Byun, Hyung-Kyoon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.35 no.5
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    • pp.1179-1189
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    • 2015
  • Continuous welded rail on bridge structure experiences typically a large amount of additional longitudinal axial forces due to longitudinal track-bridge interaction under temperature and traction/braking load effect. In order to reduce the additional axial forces, special type of fastener, such as ZLR and RLR or rail expansion joint should be applied. Sliding slab track system is known to reduce the effect of track-bridge interaction by the application of a sliding layer between slab track and bridge structure. This study presents track-bridge interaction analysis results of the sliding slab track and compares them with conventional fixed slab track on bridges. The result shows that the sliding slab track can significantly reduce the additional axil forces of the continuously welded rail, and the difference is more significant for long and continuous span bridge.