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在航空、电站、化工以及核动力工程中,有不少结构元件是在高温、周期加载条件下工作,受到蠕变、疲劳或两者的共同作用。某些元件由于受到重量和空间条件的限制,既要设计得轻巧,又不能允许它在指定的服役期限内失效。对此类元件则不能按照传统的设计观点要求其有较大的安全系数和无限寿命。允许结构元件在每一周期加载下有一定程度的弹塑性变形并按有限寿命进行设计(一般载荷循环次数N<10~4)的此类工程力学问题谓之低周疲劳(Low Cycle Fatigue简写成LCF)问题。对此类结构元件寿命估算有早期的参数关系
In aviation, power station, chemical engineering, and nuclear power engineering, there are many structural elements that work under high temperature and cyclic loading conditions and are subject to creep, fatigue, or both. Some components, because of weight and space constraints, must be designed to be light and do not allow it to fail within a specified period of service. For such components, they can not be required to have a larger safety factor and infinite life in accordance with the traditional design point of view. Allowing structural elements to have a certain degree of elasto-plastic deformation under each cycle loading and designing them according to finite life (general load cycle number N<10~4) is referred to as low cycle fatigue. LCF) problem. There is an early parameter relationship to the estimation of the lifetime of such structural elements