前言机器设备在整个运转寿命期内的可靠性和安全性,是由组成设备的零部件,特别是关键部件的使用寿命来保证的。过去,由于对零件寿命既不能计算,也无法估计,所以在传统的设计方法中,就采用给零件足够大的安全系数来实现零件的所谓“无限寿命”。即由零件材质的屈服极限(σ_s),并将零件实际所受的载荷加大若干倍来确定其危险截面的尺寸,以确保零件在机器运转中绝对不发生断裂失效现象。尽管这种方法 Foreword The reliability and safety of machinery and equipment throughout their operational life are guaranteed by the useful life of the components and parts that make up the equipment, especially critical components. In the past, since the life of a part can neither be calculated nor estimated, in the conventional design method, the so-called “infinite life” of a part is achieved by using a factor of safety sufficient for the part. That is, the yield limit (σ_s) of the material of the part and the actual load on the part to increase several times to determine the size of the dangerous cross-section to ensure that parts in the machine operation is absolutely no fracture failure phenomenon. Despite this approach