Transactions of the Korean Society of Mechanical Engineers A (대한기계학회논문집A)

The Korean Society of Mechanical Engineers (대한기계학회)
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A Numerical Analysis on Application of Laser Peening to Dissimilar Metal Welds in a Safety Injection Nozzle of Integral Reactor

일체형 원자로 안전주입 노즐 이종금속 용접부에 대한 레이저 피닝 적용의 수치 해석적 연구

  • Received : 2011.05.03
  • Accepted : 2012.03.28
  • Published : 2012.06.01
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Abstract

A numerical analysis has been performed through implicit dynamic finite element analysis using the commercial package, ABAQUS in order to investigate effect of laser peening on welding residual stress mitigation of dissimilar metal welds in a safety injection nozzle of integral reactor. The implicit dynamic finite element analysis are compared with the previous experimental results. By comparison, it is identified that the implicit dynamic finite element analysis is valid for residual stress mitigation via laser peening. Implicit static finite element residual stress analysis has been performed for the dissimilar metal welds subject to inner repair welding. The analysis results represent that both axial and hoop residual stresses are tensile on inner surface of safety injection nozzle due to inner repair welding. Also Parametric study has performed to investigate effect of laser peening variables such as maximum impact pressure, duration time of pressure, spot diameter and peening direction on the welding residual stress mitigation. As a result, it is found that laser peening has the preventive maintenance effect to mitigate mainly residual stresses of region near inner surface.

일체형 원자로의 안전주입 노즐 이종금속 용접부의 잔류응력에 대한 레이저 피닝의 효과를 고찰하기 위해 상용 프로그램인 ABAQUS를 이용하여 implicit 동적 유한요소 해석을 통해 연구를 수행하였다. implicit 동적 유한요소 해석은 기존의 실험 결과와의 비교에 따르면 레이저 피닝을 통한 잔류응력 이완에 대해 타당하다고 확인된다. 한편 내부 보수용접이 수행된 이종금속 용접부에 대해 해석이 수행되며 그 결과는 축방향 및 원환 잔류응력 모두 내부 보수용접에 기인하여 노즐의 내표면에서 인장임을 나타낸다. 또한 용접 잔류응력 이완에 대한 최대 충격 압력, 압력 지속 시간, 스폿 직경 및 피닝 방향과 같은 여러 변수의 효과를 고찰하기 위해 변수 해석 또한 수행하였다. 결과적으로, 레이저 피닝은 내표면 근처 영역의 잔류응력을 주로 이완시키는 예방정비 효과가 있음을 확인하였다.

Keywords

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