一种疲劳缺口系数计算新方法  

A new calculation approach for fatigue notched coefficient

作　　者：金丹[1] 田大将[1] 缑之飞 林伟[1] 

机构地区：[1]沈阳化工大学能源与动力工程学院110142沈阳

出　　处：《应用力学学报》2015年第2期271-275,355,共5页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金(11102119);国家重点基础研究发展计划项目(2011CB706504);辽宁省教育厅项目(L2011066)

摘　　要：针对Mod.9Cr-1Mo铁素体钢锐缺口件进行了一系列非比例载荷低周疲劳试验,采用直流电位差法测量裂纹萌生寿命,比较了非比例路径对疲劳裂纹萌生寿命的影响。结果表明:缺口件裂纹萌生寿命占总寿命的比例与非比例路径直接相关;随着非比例度增加,裂纹萌生寿命所占比例增加。采用Neuber律和Peterson模型进行缺口局部应力应变损伤的计算,结合Smith-WatsonTopper(SWT)模型进行疲劳寿命预测。采用Neuber律并结合SWT模型预测的结果与实际结果相比普遍偏低,采用Peterson模型预测的结果与实际结果相比偏高,与本文结果相比预测结果较高。基于应变路径非比例度的概念,针对Peterson模型进行修正,提出了一种新的疲劳缺口系数计算方法,结合SWT模型进行了疲劳寿命预测。结果表明,该方法改善了非比例路径下的疲劳寿命预测结果,大部分预测结果位于2倍分散带内。A series of tests for low cycle fatigue are conducted for the notched specimen of Mod.9Cr-1Mo ferrite steel under multiaxial loading. The initiation life is measured by the method of concurrent potential difference. Effect of the notched radius and nonproportional path on crack initiation life is discussed. It is shown that the ratio of the crack initiation life to the whole life is related to the strain path. The ratio of the crack initiation life to the whole life is increasing with the increase in the nonproportional degree. Smith-Watson-Topper(SWT) approach is employed to predict the fatigue life based on the local stress and strain results from Neuber rule and Peterson rule. On the whole, the prediction results are bad for above two approaches. A new approach for calculating the fatigue notched coefficient is proposed by modifying Peterson rule based on the nonproportional degree together with SWT approach to predict the fatigue life. It is shown that the acceptable prediction results can be obtained from the new approach and most results are within the factor-2 scatter band.

关 键 词：缺口件 Neuber律 Peterson模型 疲劳缺口系数 非比例度 

分 类 号：O346[理学—固体力学]