• 제목/요약/키워드: Surface residual stress

검색결과 711건 처리시간 0.027초

쇼트피닝한 스프링강의 피로균열진전 연구 (A Study of Fatigue Crack Growth in Shot Peened Spring Steel)

  • 박경동;진영범
    • 한국안전학회지
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    • 제19권4호
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    • pp.20-24
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    • 2004
  • Antifatigue failure technology take an important the part of current industries. Currently, the shot peening is used for removing the defect from the surface of steel and improving the fatigue strength on surface. Therefore in this paper the effect of compressive residual stress by shot peening on fatigue crack growth characteristics in stress ratio(R=0.1, 0.3, 0.6)was investigated with considering fracture mechanics. There is difference between shot peening specimen and unpeening specimen. Fatigue crack growth rate of shot peening specimen was lower than that of unpeening specimen. Fatigue lift shows more improvement in the shot peening material than in the unpeening material. And compressive residual stress of surface on the shot peening processed operate resistance force of fatigue crack propagation. That is the constrained force about plasticity deformation was strengthened by resultant stress, which resulted from plasticity deformation and compressive residual stress in the process of fatigue crack propagation.

Reduction of residual stress for welded joint using vibrational load

  • Aoki, Shigeru;Nishimura, Tadashi;Hiroi, Tetsumaro
    • Steel and Composite Structures
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    • 제4권5호
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    • pp.355-365
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    • 2004
  • A new reduction method of residual stress in welding joint is proposed where welded metals are shaken during welding. By an experiment using a small shaker, it can be shown that tensile residual stress near the bead is significantly reduced. Since tensile residual stress on the surface degrades fatigue strength for cumulative damage, the proposed method is effective to reduction of residual stress of welded joints. The effectiveness of the proposed method is demonstrated by the response analysis using one mass model with nonlinear springs.

표면특수가공에 따른 재료의 피로균열에 관한 연구 (A Study on the Fatigue Crack of Material by Surface Non-Traditional Machining)

  • 이태연;이승호;강진식
    • 소성∙가공
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    • 제10권3호
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    • pp.179-184
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    • 2001
  • The influence of the fatigue crack propagation by shot peening was studied in this paper. Fatigue tests were carried out on the unpeened and shot peened CT specimens. The changes of mechanical properties, residual stress, fatigue fracture surface etc. by shot peening were investigated. The mechanical properties, residual stress, fatigue surface etc. by shot peening were investigated. The mechanical peened specimen improved in fatigue life up to 14% by shot peening. The reason of increase in the fatigue life was closely related with the compressive residual stress, which was 519.7MPa on surface. Another reason was the constraint on crack opening on surface region, it is due to the decrease in slope of crack propagation direction.

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Sulfate 용액을 이용하여 전기도금 한 FCCL용 Cu 필름의 특성에 미치는 전류밀도와 pH의 영향 (Effect of Current Density and Solution pH on Properties of Electrodeposited Cu Thin Films from Sulfate Baths for FCCL Applications)

  • 신동율;박덕용;구본급
    • 한국표면공학회지
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    • 제42권4호
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    • pp.145-151
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    • 2009
  • Nanocrystalline Cu thin films for FCCL were electrodeposited from sulfate baths to investigate systematically the influences of current density, solution pH on current efficiency, residual stress, surface morphology, and microstructure of thin Cu films. Current efficiencies were measured to be approximately 100%, irrespective of the applied current density and solution pH. But these influenced residual stress, surface morphology, XRD pattern, and grain size of electrodeposited Cu thin film. The residual stress decreased with decreasing the surface roughness, but increased with increasing the fcc(111) peak strength of XRD patterns.

용접부의 천공 측정법에 의한 잔류 응력에 관한 연구 (A Study on the Residual Stresses by the Hole Drilling Measuring in the WeldZone)

  • 남궁재관
    • 한국공작기계학회논문집
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    • 제17권3호
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    • pp.115-121
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    • 2008
  • A knowloedge of the residual stress distribution at circumferential welds can increase the prediction accuracy of a fracture assessment in pipe lines. In this study, in order to predict the residual stress distribution in the circumferential butt-welded pipes were measured, using the hole-drilling strain gauge method. Their practical applications were performed in to two kinds of pipes. As the results, the following characteristics were found. On the inner surface of pipes, the circumferential and axial residual stresses were both tensile near the center line of welding and both of them changed from tensile to compressive as the distance from the center line increased. On the outer surface, however, the circumferential residual stress was shown to be tensile wile the axial residual stress was compressive near the center line of welding, and later they were revered at the region far away from the centerline.

파이프 원주방향 용접부의 잔류응력 연구 (A study on the residual stresses in circumferential welds of the pipes)

  • 남궁재관;홍재학
    • 대한기계학회논문집
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    • 제15권2호
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    • pp.693-702
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    • 1991
  • The existence of residual stress in the circumferential butt welded pipes is one of the most important problems concerning stress corrosion cracking in service. In this paper, the residual stress distributions in three kinds of circumferential butt welded pipes were measured by the hole drilling strain gage method and calculation using finite element method is performed and its results are compared with the experiments. At the inner surface of the pipe region near the center line of welding is under high tensile residual stress. However, as the distance from the center line of welding increases, the tensile component decreases and finally becomes compressive residual stress at region far away from the center line of welding. The longitudinal residual stress at the outer surface is compressive regardless of the diameter of pipe and the circumferential stress is changed rom compressive to tensile as pipe diameter increases. The results also demonstrate that the residual stress is mainly caused by self restraint bending force in the pipe welding.

마이크로 금 전해 도금 구조물의 잔류응력 측정 (Residual Stress Measurement of Micro Gold Electroplated Structure)

  • 백창욱;안유민
    • 한국정밀공학회지
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    • 제17권12호
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    • pp.195-200
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    • 2000
  • In order to find a residual stress in the micro-machined beam, first natural frequency of the beam that has the residual stress inside is analyzed using the Rayleigh's energy method. Micro gold electroplated structure is fabricated by surface micro-machining process. The made structure is clamped-clamped beam and its 1st natural frequency is measured by resonance method. For the better estimation of the residual stress, an equivalent length of micro-machined beam to ideal beam is calculated by FEM. The residual stress is estimated from the equivalent length and the measured natural frequency.

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후확산 공정 조건이 p+ 박막의 간류 응력 분포에 미치는 영향 (The Effects of the Drive-in Process Parameters on the Residual Stress Profile of the p+ Thin Film)

  • 박태규;정옥찬;양상식
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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    • pp.1007-1009
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    • 1998
  • In this paper, the effects of the drive-in process parameters on the residual stress profile of the p+ silicon film has been investigated. All the residual stress profile has been estimated by the second-order polynomial. All the coefficients of the polynomial have been determined from the measurement of the deflections of cantilevers and a rotating beam by using a surface profiler meter and by means of focusing a calibrated microscope. As the drive-in temperature or the drive-in time increases, the boron concentration decreases and the magnitude of the average residual stress decreases. If the boron concentration decreases the tensile residual stress decreases except near the surface where the magnitude of compressive residual stress increases.

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파이프 원주방향 용접부의 잔류응력분포 특성에 관한 실험적 연구 (An Experimental Study on the Residual Stress Distribution at Circumferential Welds in Pipes)

  • 남궁재관;홍재학
    • 한국정밀공학회지
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    • 제8권1호
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    • pp.41-49
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    • 1991
  • A knowledge of the resdual stress distribution at circumferential weldments can normally increase the accuracy of a fracture assessment in pipe line. In this paper, we present the measurements about the residual stress distributions at three kinds of circumferential butt welded pipes using the holl drilling strain gage method. By this experiment, we have obtined the following characteristics. At the inner surface of the pipe region near the center line of welding is under high tensile residual stress. However, as the distance from the center line of welding increases, the tensile component decreases and finally becomes compressive residual stress at region far away from the center line of welding. The longitudinal residual stress at the outer surface is compressive regardless of the diameter of pipe and the circumferential stress is changed from compressive to tensile as pipe diameter increases. The results also demonstrate that the residual stress is mainly caused by self-restraint bending force in the pipe welding.

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고탄소강 다단 신선 와이어의 표면 온도 상승에 의한 축방향 잔류응력 예측 (Prediction of Axial Residual Stress in Drawn High-Carbon Wire Resulting Due to Increase in Surface Temperature)

  • 김대운;이상곤;김병민;정진영;반덕영
    • 대한기계학회논문집A
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    • 제34권10호
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    • pp.1479-1485
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    • 2010
  • 최근 와이어의 생산성 및 고강도화를 위한 고탄소강의 고속신선으로 인해 와이어 표면의 급격한 온도상승으로 잔류응력이 크게 증가하는 문제점이 발생되고 있다. 와이어의 다단 신선 공정시에는 소성변형과 마찰열에 의하여 와이어 내부의 온도가 더욱 크게 상승하게 된다. 특히, 고속 신선의 경우 마찰에 의한 온도구배가 더욱 크게 되어 와이어 표면층에 축방향 인장 잔류응력을 과도하게 발생시킨다. 따라서, 본 연구에서는 먼저 표면 온도 상승과 축방향 잔류응력과의 관계를 규명한 다음에 와이어의 평형온도 예측 모델을 제안하고, 이를 토대로 표면 온도 상승에 의한 축방향 잔류응력 예측식을 개발하였다. 고탄소강(0.82%C)소재의 다단신선 실험을 통해 얻어진 시편에 대하여 X 선 회절을 이용하여 잔류응력을 측정하여 제안된 예측식을 검증하였다.