Heteroscedastic regression analysis method for mixed data

The heteroscedastic regression model was established and the heteroscedastic regression analysis method was presented for mixed data composed of complete data,type-Ⅰ censored data and type-Ⅱ censored data from the location-scale distribution.The best unbiased estimations of regression coefficients,as well as the confidence limits of the location parameter and scale parameter were given.Furthermore,the point estimations and confidence limits of percentiles were obtained.Thus,the traditional multiple regression analysis method which is only suitable to the complete data from normal distribution can be extended to the cases of heteroscedastic mixed data and the location-scale distribution.So the presented method has a broad range of promising applications.     

涡轮盘低循环疲劳寿命的概率分析

疲劳寿命呈现异方差特性,其标准差随弹性应变幅和塑性应变幅的减小而增大,因此在Man-son-Coffin公式中引入标准正态变量μ和线性标准差σ_e,σ_p,将ε-N曲线参数表示为标准正态变量μ的函数,建立了低循环疲劳寿命的概率模型.针对某涡轮盘材料,在低循环疲劳试验数据的基础上应用异方差回归分析方法获得了概率模型的参数,应用该模型对涡轮盘销钉孔的低循环疲劳寿命进行了Monte-Carlo数值模拟,获到了寿命的概率分布.得到可靠度0.998 7的概率寿命与轮盘技术寿命相一致,相对误差仅为4%.该模型参数均来自疲劳试验数据的统计分析,寿命预测精度高,具有较好的工程应用前景.      

涡轮盘低循环疲劳寿命概率分析

大量试验证明疲劳寿命符合对数正态分布,并且对数寿命标准差随应变水平降低而增大;在此基础上,引入对数寿命的线性标准差及标准正态随机变量μ,将Mason-Coffin公式随机化,疲劳性能参数均表示为μ的函数,建立了基于试验数据统计分析的概率寿命模型.对GH4133材料疲劳试验数据进行线性异方差回归分析,得到了疲劳性能参数的随机表达式及概率密度曲线,各参数并不服从正态分布或对数正态分布.应用该模型对某涡轮盘进行了低循环疲劳寿命可靠性分析,获得了轮盘寿命分布,对应最大概率和可靠度0.9987的寿命均与轮盘的试验分析相吻合.