破壊力学による高圧自緊容器の構造健全性保証

概要

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To assess the structural integrity of high-pressure autofrettaged vessels, systematic sensitivity analysis was conducted for fatigue crack growth life N_f from an initial defect. The factors with the greatest influence on N_f are the autofrettage radius (i.e., compressive residual stresses) and initial defect size. Each contribution was clarified quantitatively. Fracture toughness K_<IC> of the material and occurrence of partial crack closure due to compressive residual stress have no marked effect on N_f. However, increase in K_<IC> increases the critical defect size which promotes integrity through high detectability of the defect during in-service inspection. N_f for a semielliptical crack (aspect ratio = 1/6) is about 60%〜70% that for a straight crack. The latter assumption is relatively useful considering its simplicity. The concept of "leak before break" does not hold for this particular type of vessel. However, as N_f is very large compared to the assumed size of the allowable defect described in ASME Boiler and Pressure Vessel Code, Sec. XI, structural integrity is satisfactorily assured.
一般社団法人日本機械学会の論文
1994-08-25