• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.310-315
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• 2001

This paper provides validations of the reference stress based J and $C^*$ estimations, proposed in Part I, for inner, circumferential surface cracked pipes under internal pressure and global bending against detailed 3-D elastic-plastic and elastic-creep FE results. For this purpose, actual tensile properties of two typical stainless steels (TP304 and TP316) are used for elastic-plastic FE analyses and two realistic creep laws are used for elastic-creep FE analyses. For a total of twenty cases considered in this paper, agreements between the proposed reference stress based J and $C^*$ estimations and the FE results are excellent. More important aspect of the proposed estimations is that they can be used to estimate J and $C^*$ not only at the deepest point of the surface crack but also at an arbitrary point along the crack front.

• 대한기계학회논문집A
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• 제20권6호
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• pp.1798-1809
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• 1996

The purpose of this paper is to develop new Z-Factors to evaluate the behavior of circumferential surface crack in ferritic steel piping including base metal and Submerged Arc Weld(SAW) metal in nuclear power plant. The Z-factor is a load multiplier to convert plastic load to elasto-plastic load. However the current Z-Factor is a load multiplier to convert plastic load to elasto-plastic load. However the current Z-Factor gives too conservative results. In this study, a J-estimation method, SC.TNP method, which is based on GE/EPRI expression, is used to develop new Z-Factors. The desirabilities of both the SC.TNP mehtod and the new Z-Factors are examined using the previous experimental results for the circumferential surface crack in ferritic steel pippings. The results are as follows ; (1) The SC.TNP mehtod is good for describing the circumferential surface crack behavior in farritic steel pipings, while the well-known R6 mehtod and DPFAD method give too conservative results. (2) The ASME-Z-Factor method using nwe Z-Factors well predicts the behavior of circumferential surface crack in ferritic steel pipings including base emtal and SAW metal.