On repair weld residual stresses and significance to structural integrity
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This paper starts with a brief state of the art assessment on what has been learned over the last few decades in understanding residual stress development mechanisms, particularly those uniquely associated with weld repairs. A special emphasis will be given to how some of the residual stress features contribute to structural integrity of a component containing weld repairs. In contrast to initial fabrication welds, residual stresses associated with finite length repair welds tend to exhibit important invariant features, regardless of component configurations, materials, and to some degree, welding procedures. Such invariant features are associated with the severe restraint conditions present in typical repair situations. A number of weld repair cases are examined in this paper. In addition to highlighting important residual stress distribution features, fracture mechanics calculations are performed to examine how repair weld residual stresses quantitatively contribute to crack driving force as a function of crack location and size. One simple and effective technique for mitigating detrimental residual stress effects on structural integrity is also demonstrated by considering overall weld repair dimensions.
KeywordsResidual stress profiles Finite element Measurement Fitness-for-service (FFS) Engineering critical assessment (ECA) Fracture mechanics Weld repair Residual stress modeling Stress intensity factor Repair geometry
The authors acknowledge the support of this work through a grant from the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) through GCRC-SOP at the University of Michigan under Project 2-1: Reliability and Strength Assessment of Core Parts and Material System and a grant from the State Key Laboratory of Advanced Welding and Joining, under grant no. 13-M-02.
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