基于Forman方程的随机疲劳长裂纹扩展概率模型

为了提高随机疲劳长裂纹扩展率预测精度, 基于Forman方程, 发展了随机疲劳长裂纹扩展概率模型及其参数测定方法, 考虑数据分散性规律和试样数量对概率评价的影响, 得到了包含存活概率曲线、置信度曲线和两者融合曲线在内的长裂纹扩展率关系曲线, 在给定应力强度因子范围内, 裂纹扩展率服从对数正态分布条件下, 采用线性回归和极大似然法测定模型参数。对铁道车辆LZ50车轴钢裂纹扩展数据分析表明, 该模型反映了材料断裂韧度对长裂纹扩展率的影响, 克服了基于Paris-Er-dogan方程的概率模型在高应力强度因子范围预测偏于危险的缺陷, 验证了该模型的合理性。

Probabilistic Models of Random Fatigue Crack Propagation Based on Forman Equation

In order to improve the prediction precision of random fatigue crack propagation,its probabilistic models based on Forman equation and the estimation method of its parameters were developed,the effect of test data scattering regularity and sampling size on probabilistic assessment was taken into account,the models consisted of survival probability-based curves,confidence-based curves and survival-probability-and-confidence-based curves,their parameters of were measured by linear regression technique and maximum likelihood method.The prediction data of LZ50 axle steel indicate that the models show the effect of material rupture temper on long crack propagation,over come the non-conservative prediction of conventional models based on Paris-Erdogan equation in high intensity factor range,which shows that the models are reasonable and feasible.3 tabs,3 figs,16 refs.