中文摘要：

由多部位损伤（MSD）裂纹的扩展特性,归纳总结出裂纹扩展过程中两类影响裂纹扩展速度的因素,给出在循环载荷作用下基于Pairs公式的裂纹扩展增量的递推公式。根据这一递推式,推导出数个循环载荷作用下裂纹扩展长度的近似算法。同时,采用了变间隔分段处理方法。在评估了传统的载荷循环分间隔法的前提下,讨论了该方法的实现方式和所具有的优点。结合这两类改进方法,对一排共线孔有限宽薄板受远场均匀载荷作用的试样进行了计算分析,并与试验值和传统的载荷循环分间隔法的计算值做了比较。可以看出,对于普通的载荷循环分间隔处理方法,本文所提的改进方法能极大地提高结构件疲劳寿命的估算精度。对长寿命、大规模的MSD结构件使用此方法,能够在显著减小其计算规模的同时,得到一个较为精确的保守解。

英文摘要：

In view of the characteristics of multiple site damage（MSD） crack growth,two influencing factors related with the speed of crack growth are presented.Based on Pairs equation,the recursion relation of crack growth length has been deduced.Subsequently,an approximate equation derived from the recursion relation is used to compute the length of crack growth under cyclic loading.Through comparison with the constant spacing division of cyclic loading method,a variable spacing method is presented,its detailed approach is given,and its merit is discussed.One type of MSD crack configuration,that of the collinear fastener holes in rimmed thin panel,is analyzed through combining the two improvements of the approximate equation and the variable spacing method.The computed results are compared with those which made use of the constant spacing division of cyclic loading method and experiment values.These results indicate that this improved method can greatly enhance computation precision.For problems of large-scale multi-crack and long fatigue life,the proposed method can give a precise and conservative solution as well as a reduced scale of computation.