PURPOSE: To allow highly accurate estimation of creep buckling life under periodic temperature conditions by applying the ratio of temporal variation 3% of a model member in the radial direction within a predetermined time when a predetermined temperature is varied periodically. ;CONSTITUTION: Variation of creep in the radial direction within a predetermined time is previously determined, along with the ratio thereof, for a model member of same material as a cylindrical metal shell when the predetermined time is varied periodically within such range as the creep life is shortened. Subsequently, the variation of creep in the radial direction is determined within a predetermined time when the cylindrical metal shell of actual machine is used at a constant temperature. A predetermined ratio C3 is then applied thereto thus operating the variation of creep within a predetermined time when the temperature is varied periodically around the using temperature. A variation ΔW1 of creep in the radial direction of metal shell occurring during a predetermined period is also determined when the temperature is varied periodically around the use temperature and the creep buckling life is estimated based thereon.;COPYRIGHT: (C)1995,JPO
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