镍基单晶合金非对称循环载荷低周疲劳实验研究与寿命预测  

STUDY ON LOW-CYCLE FATIGUE EXPERIMENTS AND LIFE PREDICTION OF SINGLE CRYSTAL NICKEL-BASED SUPERALLOYS UNDER ASYMMETRICAL CYCLIC LOAD

作　　者：陈吉平[1] 丁智平[1] 尹泽勇[2] 刘义伦[3] 

机构地区：[1]湖南工业大学机械工程学院,株洲412008 [2]中国航空动力机械研究所,株洲412002 [3]中南大学机电工程学院,长沙410083

出　　处：《固体力学学报》2007年第2期115-120,共6页Chinese Journal of Solid Mechanics

基　　金：湖南省自然科学基金(02JJY5014)资助;湖南省教育厅重点科研基金(05A047)资助.

摘　　要：对三种不同晶体取向的DD3单晶合金试样在680℃温度下进行非对称循低周疲劳试验,表明晶体取向对疲劳寿命有显著影响.用取向函数修正总应变范围可在很大程度上消除晶体取向对疲劳寿命的影响,引入参量k表示非对称循环载荷对疲劳寿命的影响,它与循环寿命之间呈幂函数关系.根据影响单晶合金低周疲劳寿命的主要因素,提出由总应变范围、取向函数和参量k构成循环塑性应变能的计算方法。用塑性应变能作为损伤参量导出单晶合金低周疲劳寿命预测模型,利用DD3单晶合金低周疲劳试验数据进行验证,光滑试样和缺口试样试验数据分别落在2.6倍和2倍的偏差分布带内.Low cycle fatigue of single crystal superalloys DD3 was tested along three different orientations under asymmetrical cyclic loads at 680℃. It is shown that crystal orientation affects low cycle fatigue life significantly. By modifying strain range with orientation function, the effect of crystal orientation can be eliminated. A parameter k is introduced to denote the effect of asymmetrical cyclic loads and power law relationship between k and cyclic life was shown. According to main factors affecting low cycle fatigue life for single crystal superalloy, the formula of cyclic plastic strain energy, which is composed of total strain range, orientation function and the parameter k, is put forward. A low cycle fatigue life model for single crystal superalloy was deduced with cyclic plastic strain energy, and verified with fatigue tests data of single crystal superalloy DD3. The all data of smooth specimens and notched specimens fall into the factor of 2.6 and 2.0 scatter band, respectively.

关 键 词：单晶合金 非对称载荷 低周疲劳 循环塑性应变能 

分 类 号：O346[理学—固体力学]