按疲劳强度理论,叶片承受高于疲劳极限的交变应力时,每次循环都使叶片产生一定的损伤,当损伤累积到临界值时便产生破坏。汽轮机实际运行中,调频叶片大都只有当高、低周波和起停等特殊状态下,才可能出现高于疲劳极限的交变动应力,通常持续时间较短,只有经过一段时期的运行后,当这种动应力的循环次数累积到破坏的循环次数时,叶片才会因疲劳而破坏。 According to the theory of fatigue strength, when the blade is subjected to the alternating stress higher than the fatigue limit, each cycle causes some damage to the blade, and damage occurs when the damage accumulates to the critical value. Turbine actual operation, most of the frequency control blades only when high, low frequency and starting and stopping and other special conditions, may appear above the fatigue limit of alternating stress, usually short duration, only after a period of operation, when this When the cumulative number of dynamic stress cycles reaches the number of destructive cycles, the leaves will be destroyed by fatigue.