• 제목/요약/키워드: Bending

검색결과 8,308건 처리시간 0.119초

비파괴평가에 의한 라디에타소나무 단판 및 수지함침시트 표면적층 합판의 휨성능 (Bending Performances of Radiata Pine Veneers and Phenol Resin-Impregnated Sheet Overlaid Plywoods by Nondestructive Evaluation)

  • 서진석
    • 목재공학
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    • 제26권1호
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    • pp.87-96
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    • 1998
  • The bending performances were evaluated at the radiata pine plywood through veneer compositions encompassing veneer quality, ply-numbers and overlays of the high density- or medium density-phenol resin impregnated sheets (hereafter abbreviated as resin sheets) on the raw plywood. In addition, a prediction on the bending MOE of veneers and plywoods was carried out by the nondestructive testing with stresswave timer. The summarized results were as follows: I. Bending strength and bending MOE of resin sheets-overlaid plywoods in parallel surface grain direction through 5 and 7ply were increased by 13 to 45% and 17 to 34%, respectively. Resin sheets-overlay occurred an increasing effect of the strength efficiency i.e. strength perpendicular-to-grain direction versus that parallel-to-grain direction, showing the phenomenon that the plywood strength becomes greater at the perpendicular-to-grain direction of 7ply than at that of 5ply. Displacement at bending failure had a greater trend at 7ply than at 5ply, and was decreased by resin sheets-overlay. 2. After the nondestructive bending MOEs were measured for individual veneers, these veneers were rearranged in plywood-manufacture. In these plywoods, including resin sheets-overlay, the actual MOE was predictable with feasibility of $R^2$=0.53, and also the nondestructively-evaluated MOE was lower by 20% in raw plywood, and higher 20% in LVL than actual bending MOEs.

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Applicability of the induction bending process to the P91 pipe of the PGSFR

  • Kim, Nak Hyun;Kim, Jong Bum;Kim, Sung Kyun
    • Nuclear Engineering and Technology
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    • 제53권5호
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    • pp.1580-1586
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    • 2021
  • The application of induction bending processes to industrial pipe production is increasing. The induction bending process has the effect of reducing the number of inspections and preventing leaks by reducing the weld of the pipe. For these reasons, efforts have been made to apply an induction bending process to the pipe of the PGSFR under development in Korea and this is the first attempt in the SFR design. Since the PGSFR pipe has a relatively large diameter-to-thickness ratio, it is difficult to fabricate an induction bending pipe that meets the requirements. In addition, the material properties may change because the pipe heats to a very high temperature during the induction bending process. In this study, P91 pipes were fabricated by induction bending, and the results from analyzing the induction bending process' applicability to the P91 pipe of the PGSFR are examined. The various dimensional measurements of the pipes fabricated by the induction bending process were surveyed to determine whether the requirements of the ASME Code were met. The minimum thickness, ovality, and wall buckling measured in the fabricated pipe met all the requirements. Tensile, impact, and hardness tests at various locations of the fabricated pipe also satisfied the requirements.

판재 프레스 성형 제품의 형상동결성 연구 (A Study on Shape Fixability of Press Formed Parts)

  • 한수식;박기철;남재복
    • 소성가공
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    • 제8권1호
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    • pp.38-46
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    • 1999
  • This paper deals with the shape fixability of press formed parts through the use of a V-bending process and a U-bending one. The influence of material properties on the shape fixability in forming processes was investigated. A V-bending process had on optimum ben radius for each combination of parameters which caused maximum shape fixability. In the U-bending process the blank holder force could control the degree of shape fixability. A ha호 blank holding force resulted in a uniform strain distribution and increased shape fixability.

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비선형 굽힙거동을 고려한 직물의 처짐 (Deflections of Fabrics Based on Nonlinear Bending Properties)

  • 서장일;유웅렬;정관수;강태진
    • 한국섬유공학회지
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    • 제37권5호
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    • pp.286-292
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    • 2000
  • A fabric deflection model was developed based on the nonlinear beam bending theory to predict fabric deflection under its own weight. The nonlinear bending properties of fabrics were measured from the KES bending test, assuming that the bending moment is a function of curvature. Compared to the results based on the linear bending theory, the results showed better agreement with experimental results.

순수굽힘 시험기개발 및 사각관부재의 굽힘붕괴특성 연구 (Development of a Pure Bending Test Machine and Bending Collapse Characteristics of Rectangular Tubes)

  • 강신유;장인배;김헌영
    • 한국자동차공학회논문집
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    • 제6권1호
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    • pp.222-233
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    • 1998
  • A 4-point pure bending res machine is developed the evaluate the pure vending moment-rotation properties of the thin-walled tubes without imposing shear and tensile forces. The moment-rotation properties of the thin-walled tubes are measured up to and beyond collapse with the pure bending test machine. The test results are compared with those of finite element analyses and existing analytical solution.

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비대칭 "ㄱ" 단면 앵글제품의 압출굽힘 가공에 관한 연구 (A Study on the Extru-Bending Process of the Angle Product with non-Symmetric "ㄱ" Section)

  • 이경국;진인태
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2003년도 추계학술대회논문집
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    • pp.277-280
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    • 2003
  • It was investigated that the "ㄱ" type angle product could be bended with a curvature during extrusion by extru-bending process. The bending process for the "ㄱ" type angle product can be developed by the hot metal extru-bending machine with the two punches moving in the different velocity. Because of non-symmetry of product, it is important to design the ruled surface contour of dies cavity for the welding and bending with two billets. So it is designed that the multi-hole container has two non-symmetric holes and non-symmetric contour of dies entrance. The results of the experiment show that "ㄱ" type angle product can be bended by the extrusion process and that the curvature of the product can be controlled by the velocity of punch and that the defects such as the distortion of section and the thickness change of the product and the folding and wrinkling of the product did not happen after the bending processing by the extrusion bending machine.

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부직포의 굽힘강성에 대한 모델링과 구조해석에 관한 연구 (Modeling and Structural Analysis on the Bending Rigidity of Nonwoven Fabrics)

  • 박태영
    • 한국섬유공학회지
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    • 제36권6호
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    • pp.455-462
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    • 1999
  • A theoretical prediction of bending rigidity of nonwoven fabrics with different bonding characteristics is presented. To study the bending behavior of nonwoven fabrics, we have modified Freeston & Platt's model assuming both no freedom and complete freedom behavior. By reconfiguring the fiber number in a unit cell ($N_{f}$), unit cell shape, and the contribution factor (K), a new equation for bending rigidity is derived. The closer the bonding point is, the more the fibers between adjacent bonding points are likely to behave with no freedom. This fact is relevant to the contribution factor which is the relative contribution portion to bending rigidity and can be determine from the reconfigured bond area and unit cell. The experimental bending rigidity is more dependent on theoretical bending rigidity of the no freedom region than that of the complete freedom region. In general, the theoretical and experimental values of bending rigidity of the nonwoven fabrics show considerably good agreement.

트리코트 경편성물의 굽힘거동에 관한 연구 (Studies on the Bending Behavior of Tricot Warp-Knitted Fabrics)

  • 강봉춘;박신웅;배철규;황영구
    • 한국섬유공학회지
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    • 제36권11호
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    • pp.815-824
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    • 1999
  • The bending behaviour of three types of warp-knitted fabrics was studied using the KES-FB pure bending tester. Among many bending mechanisms proposed to analyze the features of fabric bending curve such as linearity, asymmetry, and hysteresis, a geometrical approach is used to describe the bending properties of warp-knitted fabrics with the changes of the fabric type and heat-setting process. Correlation analysis was performed to relate the bending properties of warp-knitted fabrics with the structural parameters including areal density and thickness of fabrics. As a result, good correlation was obtained between bending rigidity for wale as well as course and structural variables such as weight per unit area and thickness of fabric.

알루미늄 사각관의 굽힘붕괴특성에 관한 실험적 고찰 (Experimental Study on The Bending Collapse Characteristics of Aluminum Rectangular Tubes)

  • 김창수;정태은;강신유
    • 소성가공
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    • 제7권1호
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    • pp.49-58
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    • 1998
  • In this paper the bending collapse characteristics of 6XXX series aluminum rectangular tubes were studied with a pure bending collapse test rig which could apply the pure bending moment without imposing additional shear and tensile forces. Under the pure bending moment, there occured three kinds of bending collapse modes-local buckling delayed buckling and tensile failure-depending on the a, b, t (depth width thickness) and material properties. Experimental results are compared with the results of finite element method and other methods.

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Inner groove tube의 U형 Draw-Bending 가공기술에 관한 연구 (Manufacturing Technique on the U Type Draw-Bending of Inner Groove Tube)

  • 강흥식;김동성;허신;홍성인
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2003년도 춘계학술대회논문집
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    • pp.148-151
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    • 2003
  • The purpose of this study is to investigate the manufacturing technique on the U type Draw-Bending of inner groove tube. The U type tube requires the quality of product that satisfy sufficient conditions for a heat exchanger. The mandrel components act the important roles that prevent wrinkles and keep the shape of cross section of bended tube at bending process. We performed the FEM simulation using LS-DYNA software and the bending test of inner groove tube and then, compared bending simulation with bending test results about mandrel ball diameter, mandrel position and optimal clearance between mandrel and tube.

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