| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce replacement frequency of a structure generating a crack by suppressing or preventing extension of the generated crack simply at low cost without requiring extra labor. <P>SOLUTION: A plurality of slits 14 are formed at equal intervals from an end part 12 of a protective tube 10 to the depth. A crack extension obstruction member 16 of ring form is welded on the outer peripheral surface of the protective tube 10 to be spread over the depth side end parts of the slits 14. Formation of the slits 14 eases generation of thermal stress and extension of a fatigue crack c generated on the end part 12 is suppressed on an arrangement position of the crack extension obstruction member 16. From relation between thermal stress σ generated on the protective tube 10 and A = (slit length L)/(slit spacing B), the value of the A can suppressing generation of thermal stress as much as possible is selected. <P>COPYRIGHT: (C)2012,JPO&INPIT |
