• Title/Summary/Keyword: tube bending

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Ultimate moment capacity of foamed and lightweight aggregate concrete-filled steel tubes

  • Assi, Issam M.;Qudeimat, Eyad M.;Hunaiti, Yasser M.
    • Steel and Composite Structures
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    • v.3 no.3
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    • pp.199-212
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    • 2003
  • An experimental investigation of lightweight aggregate and foamed concrete contribution to the ultimate strength capacity of square and rectangular steel tube sections is presented in this study. Thirty-four simply supported beam specimens, 1000-mm long, filled with lightweight aggregate and foamed concretes were tested in pure flexural bending to calculate the ultimate moment capacity. Normal concrete-filled steel tubular and bare steel sections of identical dimensions were also tested and compared to the filled steel sections. Theoretical values of ultimate moment capacity of the beam specimens were also calculated in this study for comparison purposes. The test results showed that lightweight aggregate and foamed concrete significantly enhance the load carrying capacity of steel tubular sections. Furthermore, it can be concluded from this study that lightweight aggregate and foamed concretes can be used in composite construction to increase the flexural capacity of the steel tubular sections.

Minimum Thickness of FRP Member Applicable to FRP-Concrete Composite Deck (FRP-콘크리트 합성 바닥판에 적용 가능한 FRP 부재의 최소 두께)

  • Cho, Keun-Hee;Park, Sung-Yong;Kim, Sung-Tae;Cho, Jeong-Rae;Kim, Byung-Suk
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.317-320
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    • 2006
  • In order to determine a minimum thickness of the pultruded GFRP panel as a structural member, some experimental studies were performed. GFRP tubes with 2mm, 4mm, 6mm thickness were manufactured by pultrusion process. First, coupon tests for finding mechanical properties were carried out. Comparisons between test results and analysis results based on classical laminate theory showed large differences in case of 2mm, 4mm specimens. The reason is that it is difficult to apply appropriate pultruding force and keep layered stitched fabric flat for the pultrusion process of complex shaped FRP member with small thickness. On the consequence, we decide 6mm as a minimum thickness of FRP member. Second, 4-point bending tests were performed and the results with compared with numerical analysis. The behavior of FRP tube can be exactly predicted by numerical analysis if buckling analysis is included.

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Durability of the Flexible Shape Memory Device (형상 기억 유연 소자의 내구성 평가에 관한 연구)

  • Yang, Hee-Kyung;Kim, Hae-Jin;Kim, Dae-Eun
    • Transactions of the Society of Information Storage Systems
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    • v.11 no.2
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    • pp.36-40
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    • 2015
  • The demand for flexible devices including solar cells, memories and batteries has increased rapidly over the past decades. In most flexible devices, polymer-based materials are used to enable the mechanical deformations such as bending or folding. Shape Memory Polymers (SMPs) is a high molecular compound polymer with flexibility and shape recovery characteristics. In this work, flexible shape memory device was fabricated by simply coating the conducting material, carbon nano-tube (CNT), on a shape memory polymer. Furthermore, durability of the device under various type of mechanical deformations was assessed. It is believed that the result of this work will aid in realization of a stretchable and wearable electronic device for practical applications.

Basic Properties Test and Non-rotating Dynamic Test of Helicopter Rotor (헬리콥터 로터 블레이드의 기본 물리량 및 비회전 동특성 시험)

  • Yun, Chul Yong;Kim, Taejoo;Kee, Young-Jung;Sim, Heon-Su;Kim, Seung-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.10a
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    • pp.103-108
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    • 2013
  • This paper describes basic properties tests and non-rotating dynamic test for rotor blade, flexbeam, and torque tube of which bearingless rotor in helicopter consists. A basic properties test are bending and twist test to find the flap stiffness, lag stiffness, and twist stiffness of specimens. The purpose of dynamic test is to find natural frequencies and modes in non-rotating state. The test results are used to update the analysis model. The updated analysis results using rotorcraft comprehensive code match the tests quite well. The updated model input based on the tests will be utilized to analysis the conditions of rotating whirl tower test before the whirl test and will be compared with the whirl tower test results.

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Torsional strength model of reinforced concrete members subjected to combined loads

  • Ju, Hyunjin;Lee, Deuckhang;Zhang, Wei;Wang, Lei
    • Computers and Concrete
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    • v.29 no.5
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    • pp.285-301
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    • 2022
  • This study aims at developing a torsional strength model based on a nonlinear analysis method presented in the previous studies. To this end, flexural neutral axis depth of a reinforced concrete section and effective thickness of an idealized thin-walled tube were formulated based on reasonable approximations. In addition, various sectional force components, such as shear, flexure, axial compression, and torsional moment, were considered in estimating torsional strength by addressing a simple and linear strain profile. Existing test results were collected from literature for verifications by comparing with those estimated from the proposed model. On this basis, it can be confirmed that the proposed model can evaluate the torsional strength of RC members subjected to combined loads with a good level of accuracy, and it also well captured inter-related mechanisms between shear, bending moment, axial compression, and torsion.

A Study on Development of One-Piece Manufacturing Process for Automotive Cowl Cross Bar (자동차용 카울크로스바의 일체화 성형 공정 개발에 관한 연구)

  • Kim, Hong-Seok;Youn, Jae-Woong
    • Journal of the Korea Convergence Society
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    • v.8 no.12
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    • pp.275-281
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    • 2017
  • The automobile cowl cross bar which is a backbone frame part inside the cockpit module has been designed with more complex geometries recently due to demands of its enhanced functions and reduced weight of car. The traditional manufacturing process using welding between tubes with different diameters shows several problems such as poor mechanical characteristics and appearance, etc. Therefore, in this study, manufacturing processes which can eliminate the welding process were developed by applying one-piece metal forming processes such as tube drawing and radial swaging. As results, it was found that the one-piece manufacturing processes give better bending strength than the traditional welding process and the swaging process shows the lowest manufacturing cost.

Influence of stiffeners on the performance of blind-bolt end-plate connections to CFST columns

  • Ding, Fa-xing;Pan, Zhi-cheng;Liu, Peng;Huang, Shi-jian;Luo, Liang;Zhang, Tao
    • Steel and Composite Structures
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    • v.36 no.4
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    • pp.447-462
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    • 2020
  • The paper aims to investigate the mechanical mechanism and seismic effect of stiffeners in blind bolt endplate connection to CFST column. A precise 3D finite element model with considering the cyclic properties of concrete and steel materials was established, and the efficiency was validated through monotonic and cyclic test data. The deforming pattern and the seismic performance of the unstiffened and stiffened blind bolt endplate connections were investigated. Then a parametric analysis was conducted to analyze the contribution of stiffeners and the joint working behaviors with endplate under cyclic load. The joint stiffness classifications were compared and a supplement stiffness classification method was proposed, and the energy dissipation ability of different class connections were compared and discussed. Results indicated that the main deformation pattern of unstiffened blind bolt endplate connections was the local bending of end plate. The vertical stiffeners can effectively alleviate the local bending deformation of end plate. And influence of stiffeners in thin endplate and thick endplate was different. Based on the stiffness of external diaphragm welded connection, a more detailed rigidity classification was proposed which included the pin, semi-rigid, quasi-rigid and rigid connection. Beam was the main energy dissipation source for rigid connection. For the semi-rigid and quasi-rigid connection, the extended endplate, stiffeners and steel beam would all participate in the energy dissipation.

An Evaluation on Bending Behaviors of Conical Composite Tubes for Bicycle Frames (자전거 프레임용 원추형 복합재 튜브의 굽힘 거동 분석)

  • Hwang, Sang-Kyun;Lee, Jung-Woo;Hwang, Hui-Yun
    • Composites Research
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    • v.29 no.6
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    • pp.358-362
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    • 2016
  • Mechanical properties of static and dynamic behavior became important since the use of conical composite tubes in large structures such as aerospace, planes, and submarines as well as leisure goods such as bicycle frames, fishing rods, and golf shafts. In the past, the mechanical property prediction model for static behavior was studied using vibration, bending, and buckling. But there is a need to study how fiber orientation error affects mechanical properties of conical composite structure because the model assumes constant fiber orientation angle. The purpose of this study is to derive an equation that can predict the static behavior of conical composite tube for bicycle frames by considering fiber orientation error with respect to various design parameters.

Study on strength of reinforced concrete filled circular steel tubular columns

  • Hua, Wei;Wang, Hai-Jun;Hasegawa, Akira;Shioi, Yukitake;Iwasaki, Shoji;Miyamoto, Yutaka
    • Structural Engineering and Mechanics
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    • v.19 no.6
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    • pp.653-677
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    • 2005
  • Concrete filled steel tubular columns (CFT) are widely used in civil engineering works, especially in large scale of works because of high strength, deformation, toughness and so on. On the other hand, as a kind of strengthening measure for seriously damaged reinforced concrete piers of viaduct in Hansin-Awaji earthquake of Japan in 1995, reinforced concrete piers were wrapped with steel plate. Then, a new kind of structure appeared, that is, reinforced concrete filled steel tubular column (RCFT). In this paper, compression test and bending-shearing test on RCFT are carried out. The main parameters of experiments are (1) strength of concrete, (2) steel tube with or without rib, (3) width-thickness ratio and (4) arrangement of reinforcing bars. According to the experimental results, the effect of parameters on mechanical characteristics of RCFT is analyzed clearly. At the same time, strength evaluation formula for RCFT column is proposed and tested by experimental results and existed recommendations (AIJ 1997). The strength calculated by the proposal formula is in good agreement with test result. As a result, the proposed evaluation formula can evaluate the strength of RCFT column properly.

Optimum Design of Dynamic Vibration Absorber for Reducing Bending Vibrations of Two-Piece Vehicle Drive Line (2축 분할식 차량 구동라인의 굽힘진동 저감을 위한 동흡진기 최적설계)

  • Lee, Sang-Beom;Yoo, Young-Sun
    • The Journal of the Acoustical Society of Korea
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    • v.29 no.2
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    • pp.118-124
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    • 2010
  • In this paper, design parameters of dynamic vibration absorber, which is used to reduce bending vibrations of a vehicle drive line, is optimized. For obtaining the correct dynamic response characteristics, a flexible-body drive line is made by applying the flexibility data extracted from vibration analysis of propeller shafts to the drive line dynamic model. Inner tube mass, rubber stiffness and rubber damping coefficient of the dynamic vibration absorber are taken as design parameters for optimization. To minimize the vertical acceleration of the drive line, a second-order regression equation of the objective function is generated by performing the central composite experimental design with 3 factors, 2 levels and 15 test runs. And the design parameters of the dynamic vibration absorber are determined by using optimization program. The vehicle model with optimized dynamic vibration absorber reduces the vertical acceleration peak of the drive line by 17.1 % in compared with the initial model.