尽管名义应力法仍然广泛地被应用来估算机件的寿命,但是,无论从准确性或是从可靠性而言,都还不够理想,存在着某些缺点。这些缺点主要在于:名义应力法首先假定机件是理想的连续体,承载后的应力处在弹性极限范围之内,而实际的机件不是理想的连续体,由于结构形状的变化、材料本身和制造过程中的缺陷,总是存在着应力集中部位,机件的破坏大都产生在这些应力集中部位。对于应力集中部位的应力应变分析,是十分复杂的,尽管名义应力还在弹性范围之内,但在应力集中部位,应力有可能 Although the nominal stress method is still widely used to estimate the life of mechanical parts, it is not ideal enough either in terms of accuracy or reliability, and there are some shortcomings. These shortcomings mainly lie in the fact that the nominal stress method first assumes that the part is an ideal continuous body and the post-loaded stress is within the elastic limit, whereas the actual part is not an ideal continuous body. Due to the change of the shape of the structure and the material itself The defects in the manufacturing process, there is always the stress concentration parts, the destruction of mechanical parts are mostly produced in these parts of the stress concentration. Stress-strain analysis of stress concentration is very complicated, although the nominal stress is still within the elastic range, but in the stress concentration site, there is a possibility of stress