• Title/Summary/Keyword: Allowable bending stress

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Evaluation of Allowable Bending Stress of Dimension Lumber; Confidence Levels and Size-adjustment

  • Pang, Sung-Jun;Lee, Jun-Jae;Oh, Jung-Kwon
    • Journal of the Korean Wood Science and Technology
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    • v.41 no.5
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    • pp.432-439
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    • 2013
  • The aim of this study was to investigate the processes for evaluating the allowable bending stress. The confidence levels and the size-adjustment in standards were reviewed with experimental data. The results show that, (1) KS F 2152 was more strict than others overseas standards due to the higher confidence level. The 5% NTL of bending strengths by a method in KS F 2152 were lower than the overseas standards and more specimens were required for evaluating the structural properties according to KS F 2152. (2) Due to the absence of size-adjustment method in domestic standards, the specified size and the exponential parameters on the size-adjustment equation were reviewed by size factors. The specified size (width: 286 mm, length: 6096 mm), and the exponential parameters (w: 0.29, l: 0.14) will be suitable for developing the allowable bending stress in domestic standard. (3) The size adjusted allowable bending stresses of No. 2 grade Korean pine were lower than the allowable stresses tabulated in KBC even though less strict method (75% confidence level) to calculate 5% value was used. The allowable stresses tabulated in KBC are needed to be reviewed by continuous experimental data.

A Study the Development of Involute Spur Gears Profiles Strength (인벌류트 스퍼기어 치형 강도에 관한 연구)

  • Cho, Seong-Cheol
    • Journal of the Korean Society of Industry Convergence
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    • v.9 no.4
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    • pp.269-276
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    • 2006
  • Strength Design method for involute spur gears is developed. The developed gear strength design system can design the optimized gear that minimize the number of pinion teeth with face tooth. Method of optimization is matrix form which is developed from this study. Design variables are transmitted power, gear volume, gear ratio, allowable contact stress and allowable bending stress, etc. Gear design method developed this study can be apply to the gears of plants, machine tools, automobiles.

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A Study on Technology for Involute Bevel Gear Design (인벌류트 베벨기어 설계 기술에 관한 연구)

  • Cho, Seong-Cheol
    • Journal of the Korean Society of Safety
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    • v.18 no.4
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    • pp.44-50
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    • 2003
  • Design method for involute bevel gears is developed. The developed gear design system can design the optimized gear that minimize the number of pinion teeth with face tooth. Method of optimization is MS(matrix search) which is developed from this study. Design variables are pressure angle 20., transmitted power, gear volume, gear ratio, allowable contact stress and allowable bending stress. etc. Gears design method developed this study can be applied to the plane, helicopter, printer, machine tools.

A Study the Development of Bevel Gears Design System (베벨기어 설계 시스템 개발에 관한 연구)

  • 조성철
    • Proceedings of the Korean Institute of Industrial Safety Conference
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    • 2002.11a
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    • pp.263-269
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    • 2002
  • Design method for Involute bevel gears is developed. The developed gear design system can design the optimized gear that minimize the number of pinion teeth with face tooth. Method of optimization is MS(matrix search) which is developed from this study. Design variables are pressure angle 20, transmitted power, gear volume, gear ratio, allowable contact stress and allowable bending stress, etc. Design method developed this study can bd applide to the plane, machine tools, automobiles.

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A Study on Automatic Technology for a industrial Industrial Involute Gears Design (산업용 인벌류트 치차 설계를 위한 자동화 기술에 관한 연구)

  • 조성철;변문현
    • Journal of the Korean Society of Safety
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    • v.12 no.4
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    • pp.39-46
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    • 1997
  • This study describes a computer aided design system on involute gear for power transmition. Input data for gear design are pressure angle $20^{\circ}$, transmitted power, gear volume, gear ratio, addendum ratio of rack, dedendum ratio of rack, edge radius of rack, allowable contact stress and allowable bending stress etc. Bending strength contact strength and scoring are considered as the design constraints. Method of optimization developed this study. The developed gear design system can design the optimized gear that minimize the number of pinion teeth with face tooth.

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Structural Design of Box Beam Header

  • Jang, Sang-Sik;Park, Young-Ran;Kim, Yun-Hui
    • Journal of the Korea Furniture Society
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    • v.18 no.4
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    • pp.287-295
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    • 2007
  • To obtain a design data for box beams used as headers in light-frame timber construction, $2{\times}6\;(38{\times}140mm),\;2{\times}8\;(38{\times}184mm),\;2{\times}10\;(38{\times}235mm)\;and\;2{\times}12\;(38{\times}286mm)$ members were built as box beam specimens for bending tests. The allowable bending stresses for box beams were obtained through bending tests of these specimens, and span tables were calculated for various loading conditions based on the allowable bending stresses obtained. The allowable bending stresses were determined as the bending stresses at 10mm deflection of specimens from the results of bending tests of box beam specimens. Span tables for box beams were obtained assuming five loading conditions for headers used in exterior walls and two loading conditions for headers used in interior walls. Among these 7 loading conditions, 5 loading conditions applied to headers in exterior walls included the dead loads, the live loads and the snow loads and 2 loading conditions applied to headers in interior walls included the dead loads and the live loads.

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Effects of Finger-joint on Bending Performance of Square Timbers Produced from Domestic Small Diameter Larch Logs (핑거조인트가 국산 낙엽송 소경각재의 휨성능에 미치는 영향)

  • Kim, Yun-Hui;Jang, Sang-Sik
    • Journal of the Korean Wood Science and Technology
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    • v.42 no.3
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    • pp.301-308
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    • 2014
  • Despite Korea forest take 63.7% of the nation's territory, productivity of domestic structural lumber is low. Studies of domestic small lumbers need to be improved domestic structural timber productivity. In this study, small diameter lumber and finger joint small diameter lumber took bending test to calculate MOE and MOR. MOE of small diameter lumber was $9.3kN/mm^2$ and MOE of finger joint small diameter lumber was $15.4kN/mm^2$. Allowable standard bending stress of small diameter lumber and finger joint small diameter lumber was calculated according to ASTM D 2915. Standard allowable bending stress of small diameter lumber was $12N/mm^2$ and standard allowable bending stress of finger joint small diameter lumber was $11N/mm^2$. Standard allowable bending stress of finger joint small diameter lumber should be considered to design structural beam members.

Allowable Stress Calculation of Domestic Japanese Larch Small Diameter Lumbers (국내산 낙엽송 소경각재의 허용응력 산출)

  • Kim, Yun-Hui;Shin, Il-Joong;Yang, Jung-Mo;Jang, Sang-Sik
    • Journal of the Korea Furniture Society
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    • v.23 no.2
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    • pp.214-221
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    • 2012
  • Sustainable energy consumption and increasing $CO_2$ emissions stimulate Eco-friendly industry. Wood has positive various properties as alternative energy such as solar, wind and water. Wood provide lumber, pallet, paper, pulp and fuel through production process. Even Korea republic has 63.7% of forest rates, weather condition makes low forestry production capacity. For utilization of domestic small diameter log needs study mechanical properties. In this study, various properties tested on domestic Japanese Larch small diameter lumbers and make mechanical properties table for allowable stress calculation. Result of compressive test, allowable compressive stress is 13 MPa. Allowable bending stress is 12 MPa.

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Analysis on the Characteristics of the Stranded Wire Disconnected by Bending Stress (구부림 피로에 의한 연선의 반단선 특성 해석)

  • Shong, Kil-Mok;Choi, Chung-Seog;Kim, Dong-Woo;Kwak, Hee-Ro
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07a
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    • pp.464-467
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    • 2003
  • In this paper, we analyzed on the characteristics of the stranded wire disconnected by bending stress. The stranded wire that used in the experiment are PVC insulated flexible cords(VCTFK) of $0.75mm^2,\;1.25mm^2,\;and\;2.0mm^2$. They are used to connect the load in low voltage. The stranded wires disconnected by bending stress were magnified with optical microscope. Using X-ray, the disconnected wire were photographed. we compared mechanical characteristics of the stranded wire between disconnected tendency and allowable current. On the mechanical strength of vinyl captyre ellipse type cords under bending stress, $1.25mm^2$ VCTFK was the strongest of them. When it was bended $826.3{\pm}7\;times$, it appeared the disconnected tendency that element wires of $1.25mm^2$ VCTFK are more about 1.67 times than element wires of $0.75mm^2$ VCTFK. In mechanical strength, $1.25mm^2$ VCTFK is higher about 1.7 times than $0.75mm^2$ VCTFK. Therefore, we found out that mechanical strength will be higher, if element wire is a lot. In comparison with bending stress, $1.25mm^2$ VCTFK is the strongest among samples, and then it is the most useful in wires of movable type.

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The analysis of bending processes in $Nb_{3}$Sn Cable-in-Conduit Conductors ($Nb_{3}$Sn 도관 케이블 도체의 굽힘변형 해석)

  • 남현일;이호진;박재학
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2002.02a
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    • pp.259-262
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    • 2002
  • Cable-in-Conduit Conductors (CICC) have been used for fabrication of nuclear fusion magnets. Bending process is included in fabrication of superconducting magnet such as termination of conductors. Because of plastic deformation by bending process, there can be a large residual stress and change of shape in bent conductors. Void volume fraction in conductors is also changed by bending process. In this study, Commercial code was used to analyze the bending process at various bending curvature radius. The calculated residual stress of conductors bent at less than about 40cm curvature radius exceeded the allowable stress.

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