基于临界距离-临界平面方法预测DZ125缺口低循环疲劳寿命  

Low Cycle Fatigue Life Prediction of Notched DZ125 Component Based on Combined Critical Distance-Critical Plane Approach

作　　者：黄佳[1] 杨晓光[1] 石多奇[1] 王井科[2] 胡晓安[1] 

机构地区：[1]北京航空航天大学能源与动力工程学院 [2]中国人民解放军95899部队

出　　处：《机械工程学报》2013年第22期109-115,共7页Journal of Mechanical Engineering

摘　　要：考虑到镍基定向凝固合金滑移相关的塑性流动和裂纹萌生机制,视其面心立方晶体结构中可能开动的滑移系为临界平面并以最大分切应变范围(?γmax)为损伤参数,分别采用热点法和临界距离理论(Theory of critical distance,TCD)对DZ125的低循环疲劳寿命进行分析和预测。研究结果表明,基于热点法的临界平面法其寿命预测偏保守,且应力集中程度越大其保守程度越明显;运用TCD时发现,缺口试件的临界距离不仅同材料、失效寿命以及应力比有关,同应力集中程度亦相关。如果以尖锐缺口试件为校准试样或采用平均思想处理临界距离,其寿命分散带均大于10倍。而假定临界距离同应力集中程度相关时获得的寿命预测分散带缩小为2倍。Considering the plastic flow and crack initiation mechanism occurred on the slip systems of ni-base directionally solidified （DS） supealloy, the critical plane method with the combination of ＂hot point＂ concept and theory of critical distance（TCD） is conducted on low cycle fatigue （LCF） life prediction of notched DZ125 at 850 ~C. The damage parameter on slip planes is the maximum resolved shear strain range A~,m~. The obtained results exhibits that the prediction ability of the ＂Hot point＂ method is conservative and Kt related. Furthermore, TCD is introduced and the analysis results show that the critical distance is not only related to material, failure cycles and stress ratio, but also related to the degree of stress concentration. Using the sharp notch as standard sample or dealing critical distance with statistics average method, the scatter band of predicted life is more than 10. However, based on the Kt modified critical distance, the scatter band is increased to 2.

关 键 词：低循环疲劳 临界距离理论 临界平面法 滑移系 定向凝固镍基高温合金 

分 类 号：V231[航空宇航科学与技术—航空宇航推进理论与工程]