改进的FCG软件试验数据处理方法

应用软件FCG(MTS Fatigue Crack Growth TestW are)采用七点递增多项式局部拟合的方法,计算疲劳裂纹扩展速率da/dN,导致计算值分散度很大。经过详细分析,提出采用正交多项式的线性组合作为疲劳裂纹长度a与载荷循环数N之间关系的拟合目标函数,再用直接求导的方法计算da/dN。这样减小了da/dN的分散度,提高了Paris公式参数拟合和门槛值计算的精度。

Improving Data Processing Method of FCG TestWare

The seven points incremental polynomial local fitting method is used by MTS Fatigue Crack Growth TestWare to calculate the fatigue crack growth rates,which results wider scattering of the da/dN data points.On the basis of detailed analysis,it is proposed that the linear combination of the normal polynomial could be taken as the fitting objective function for the data points of crack length a and load cycles N.Then the fatigue crack growth rates can be calculated directly by the derivative method.In this method,the scattering of the fatigue crack growth rates' data points is decreased,and the precision of the Paris parameters fitting and the threshold calculation is improved.