• 제목/요약/키워드: Fillet weldment

검색결과 44건 처리시간 0.054초

온도구배가 있는 필릿용접에서 초음파의 전파와 탐촉자의 위치 결정 (The determination of transducer location and ultrasonic wave propagation through temperature gradients in fillet are welding)

  • 정선국;조형석
    • Journal of Welding and Joining
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    • 제15권3호
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    • pp.109-117
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    • 1997

  • The temperature gradient in weldment changes the transit time and distorts the direction of the ultrasound beam to the higher temperature regions due to the lower sound speed in the hotter regions of the weldment. This paper describes a ray-tracing method for calculating the effects of temperature gradients on ultrasonic propagation in fillet arc weldig. In the method, weldment is conceptually devided into a number of layers and the refraction and sound speed at each layer is calculated using the temperature which calculated from analytical solution. Calculating the time and location of echoes arrived from various interfaces around a molten weld pool determines the optimum location of ultrasonic transducers and the correct position of flaws.

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필렛 용접부의 비접촉 초음파 검사 기법 (Non-contact Ultrasonic Inspection Technology of Fillet Weldments)

  • 박익근;이철구;김현묵;박태성;김용권;조용상;송원준;안형근
    • Journal of Welding and Joining
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    • 제23권5호
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    • pp.37-42
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    • 2005

  • The non-destructive Inspection of the fillet weldment has difficulties due to its geometrical complexity and uneasy access. The surface shear horizontal wave (SH-wave), however, has been successfully applied to the detection of cracks on the surface and sub-surface of the filet weldment heel part. The conventional ultrasonic inspection using the surface SH-wave is usually a contact method using piezoelectric transducer. Thus, it is not suitable for a field application because the reliability and repeatability of inspection are significantly affected by test conditions such as couplant, contact pressure and pre-process. In order to overcome this problem, a non-contact SH-wave inspection method using EMAT is propose. The experimental results with this non-contact method are compared with those with a conventional ultrasonic method in fillet weldment with slit type defects. It is shown that the non-contact inspection technique requires simple procedure and less time in the fillet weldment inspection.

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유한요소법을 이용한 필렛용접 이음부의 잔류응력분포 (Residual Stress Distribution on the Fillet Weldment used by Finite Element Method)

  • 김현성;우상익;정경섭
    • 한국강구조학회 논문집
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    • 제12권2호통권45호
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    • pp.197-207
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    • 2000

  • 본 연구는 유한요소법을 이용해서 시간이력 열전도해석과 열탄성해석을 통해 필렛용접 이음부에서의 잔류응력분포를 측정하였다. 필렛용접은 1패스 용접이며, 경계조건으로는 표면유속조건과 온도에 의존하는 재료의 특성치를 고려하여 잔류응력을 평가하였다. 여기서, 용접입열양을 변수로 하였다. 그리고, 열탄성해석에 의해 잔류응력 평가할 때 중요한 문제로 언급되고 있는 cut-off 온도 설정에 대해 조사하였다. 또한, 시험체에서 구멍뚫기 방법에 의해 잔류응력분포를 측정하여 유한요소법에 의한 잔류응력분포와 비교하였다. 그 결과, 용접부에서는 재료의 항복강도 수준에 해당하는 인장잔류응력이 측정되었으며, 유한요소해석에 의한 수치해석 결과는 구멍뚫기 방법에 의한 측정치 및 다른 연구자의 측정치와 비교적 일치하는 것으로 나타났다. 그리고, Cut-off 온도는 재료의 항복강도가 나타나는 온도로 설정하는 것이 효과적임을 알 수 있었다.

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수도용 대형 강관 용접부의 응력분포에 미치는 각장(leg of fillet)의 영향 (Effect of leg of fillet on stress distribution in weldments of large steel water pipes)

  • 김성도;배강열;나석주
    • Journal of Welding and Joining
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    • 제10권3호
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    • pp.54-62
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    • 1992

  • Large steel water pipes are joined prevalently by bell and method and welded at inside and outside of lapped parts. According to the Korean Standard(KS) for fabrication of water pipes, the weldments are designed to have the length of leg which is same as or larger than the thickness of the pipe. It is recently pointed out that the standard size of weldments is too large, which results in an excessive consumption of material and labor. In this study, several cases of weldments having different sizes were investigated to reduce the length of leg to the effective size. For each case, the analysis of stresses was carried out to evaluate the safety of the welded pipes by using a package program, ANSYS, under the consideration of the loading condition of water pipes which includes the soil pressure on the pipe, the load over the road, and temperature change of the pipe. The results of this study revealed that the weldment which has the length of leg of the size over 0.7*thickness of the pipe could provide a stress level below the yield strength. Especially when the length of leg is 85% of the wall thickness, the maximum equivalent stress is only slightly higher than that of the leg of fillet of the size of 1.0*pipe thickness.

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필릿 용접부의 각변형량 예측에 관한 연구 (A study on the estimate of the angular distortion for a fillet weldment)

  • 양영수;이세환;조수형
    • Journal of Welding and Joining
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    • 제15권4호
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    • pp.63-69
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    • 1997

  • Welding distortion is more serious problem than any other problems caused by welding process, especially, in the heavy-industrial place. These welding distortions are caused by nonuniform heating and cooling of metal during and after welding operations. And these distortion quantities are must be known to worker in production line because distorions are important role in assembling part. Therefore an analytical model to explain and predict the welding distortion are needed. A numerical analysis of welding distortion which is inelastic behavior of weldment would require the three dimensional calculation. But computing time and memory would be very large, and the resulting cost might be unacceptable. Therefore we use a numerical technique for two dimensional analysis in the section normal to the weld direction of weldment under an assumption of quasi-stationary conditions. But the result of the calculation under two dimensional(plane strain) assumption was not satisfied as compared with experimental result. This paper proposed a technique for analysing the welding angular distortion by using a constraint boundary condition on the two dimensional finite element model. The simulation results revealed that the constraint boundary model could more reasonably describe the welding distortion than the plane strain model did.

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