TTCI数据概率评估840D车轮辐板孔裂纹扩展速率的研究

Probability Estimation on Crack Growth Rate of 840D Wheel Web with a Hole

840D车轮辐板孔裂纹扩展速率da/dt具有很大分散性,其分散性主要来源于车轮载荷分散性,可用da/dt=Q.a(a≤35mm时)来表达,裂纹扩展参数Q代表了da/dt的分散性。现场调查获得840D车轮辐板孔裂纹有效数据共3974组,是裂纹长度α及其形成时间t的孤立数据点。通过统计方法分析表明不同裂纹长度下的裂纹形成时间分布(TTCI),很好地符合双参数威布尔分布。建立了裂纹扩展的概率模型,通过不同裂纹长度及其对应的不同可靠度下的裂纹形成时间,拟合获得了不同可靠度下的裂纹扩展速率参数Q。数据分析表明Q服从正态分布,即,O～N(0.918,0.3112)。

The crack growth rate da/dt of 840D wheel web is of great dispersion,which mainly roots in dispersion of wheel load.It can be expressed as da/dt = Q·a,where Q reflects the dispersion of da/dt.3974 effective isolated data of crack length a and time to crack initiation t (TTCI) were obtained from field investigation.Statistical analysis shows that the TTCI well agrees with two parameter Weibull distribution.Based on crack growth probability model and statistical correspondence principle of TTCI evolution with crack growth,crack growth rate parameter Q with different probabilities is obtained and Q complies with Normal distribution,i.e.Q～N (0.918,0.3112).