Crack initiation and subcritical crack growth in glass sheet and SIC bar specimen under static loading were investigated to study the failure process. It has been demonstrated that the lifetime ...Crack initiation and subcritical crack growth in glass sheet and SIC bar specimen under static loading were investigated to study the failure process. It has been demonstrated that the lifetime process of brittle materials involves three possible forms of crack growth: subcritical crack growth, partly subcritical crack growth and instantaneous fracture without subcritical crack growth. Curves of ν-K obtained in step-by-step static fatigue tests and in constant loading rate tests showed different trends for borosilicate glass sheet. α-SiC that is generally considered immune to mechanical fatigue effect and environmental attack was also tested under static loading and the lifetime was measured. The results showed that the threshold load to damage effect was over 80% of the initial strength for the SiC.展开更多
高温环境下合金600在压力和输送介质的耦合作用下易发生应力腐蚀开裂,是合金管道的潜在失效模式,在多种影响因素共同作用下,一般参数化模型存在预测精度不高、泛化能力较差的问题,影响合金管道安全评估的准确性。将Faure序列初始种群、...高温环境下合金600在压力和输送介质的耦合作用下易发生应力腐蚀开裂,是合金管道的潜在失效模式,在多种影响因素共同作用下,一般参数化模型存在预测精度不高、泛化能力较差的问题,影响合金管道安全评估的准确性。将Faure序列初始种群、自适应引力全局搜索、精英保留策略局部搜索引入烟花算法,使用改进烟花算法(Improved Fire War Algorithm,IFWA)对结合Lasso回归和随机森林组成的回归增强随机森林算法(Regression-Enhanced Random Forest,RERF)超参数基学习器数量(n_estimate)、树的最大深度(max_depth)寻优,以RMSE为目标值使RERF达到全局搜索和局部搜索最优,形成基于IFWA-RERF的合金600应力腐蚀裂纹扩展速率预测模型,引入MAE和R2作为模型性能评价指标,建立数据集与测试集进行对比。结果表明:使用基于IFWA-RERF的合金600应力腐蚀裂纹扩展速率预测结果最接近实际数据,预测精度和稳定性均优于其他对比模型,有助于建立准确的安全评估模型。展开更多
基金This work was supported by the National Natural Science Foundation of China(No.59872035 and No.59902227)the Science Foundation of Beijing(2002019).
文摘Crack initiation and subcritical crack growth in glass sheet and SIC bar specimen under static loading were investigated to study the failure process. It has been demonstrated that the lifetime process of brittle materials involves three possible forms of crack growth: subcritical crack growth, partly subcritical crack growth and instantaneous fracture without subcritical crack growth. Curves of ν-K obtained in step-by-step static fatigue tests and in constant loading rate tests showed different trends for borosilicate glass sheet. α-SiC that is generally considered immune to mechanical fatigue effect and environmental attack was also tested under static loading and the lifetime was measured. The results showed that the threshold load to damage effect was over 80% of the initial strength for the SiC.
文摘高温环境下合金600在压力和输送介质的耦合作用下易发生应力腐蚀开裂,是合金管道的潜在失效模式,在多种影响因素共同作用下,一般参数化模型存在预测精度不高、泛化能力较差的问题,影响合金管道安全评估的准确性。将Faure序列初始种群、自适应引力全局搜索、精英保留策略局部搜索引入烟花算法,使用改进烟花算法(Improved Fire War Algorithm,IFWA)对结合Lasso回归和随机森林组成的回归增强随机森林算法(Regression-Enhanced Random Forest,RERF)超参数基学习器数量(n_estimate)、树的最大深度(max_depth)寻优,以RMSE为目标值使RERF达到全局搜索和局部搜索最优,形成基于IFWA-RERF的合金600应力腐蚀裂纹扩展速率预测模型,引入MAE和R2作为模型性能评价指标,建立数据集与测试集进行对比。结果表明:使用基于IFWA-RERF的合金600应力腐蚀裂纹扩展速率预测结果最接近实际数据,预测精度和稳定性均优于其他对比模型,有助于建立准确的安全评估模型。
