摘要
疲劳是导致工程结构或构件断裂的主要原因。针对某型航空发动机涡轮盘用GH4133B合金,对其疲劳损伤和断裂机理进行研究。测量GH4133B合金的疲劳极限,并考察电阻变化与疲劳周次之间的关系。对试验数据进行回归与概率统计分析,获取理论疲劳极限与P-S-N关系表达式,推导电阻变化率表征的损伤演化方程。结果表明,GH4133B的理论与实测疲劳极限吻合较好,修正Chaboche损伤模型能较精确预测GH4133B的疲劳损伤。应用扫描电子显微镜对疲劳断口进行微观分析。由断口形貌分析可知,GH4133B疲劳源区呈混合断裂模式,断面上出现二次裂纹。扩展区呈现出典型的疲劳条带,且在较低应力幅值下可观察到脆性疲劳条带。瞬断区呈准脆性断裂模式,且韧窝的尺寸和数量随应力幅值的增加而减小。
Fatigue is the main reason for fracture of structure.The fatigue damage and fracture mechanism of GH4133B superalloy used in turbine disk of aero-engine are studied.The fatigue limit of GH4133B is measured,and the relation between the ratio of resistance change and the fatigue cycle is investigated at room temperature.The experiment data are processed by using the regression analysis and the probabilistic method,the theoretical fatigue threshold and P-S-N representation are achieved,and the fatigue damage evolution equation is deduced.The results show that the theoretical fatigue threshold agrees well with the experimental one,and the modified Chaboche model can precisely predict the accumulated damage of GH4133B.Then,the fracture surfaces of GH4133B are micro analyzed by using scanning electron microscopy(SEM).It can be found from the fracture surface morphologies that in the initiation region,the superalloy exhibits a mixed fracture mode and many secondary cracks emerge.In the propagation region,a series of typical fatigue striations can be observed,especially at lower stress amplitude,some brittle fatigue striations can be found.In the final rupture region,the fracture surface appears as a typical semi-brittle fracture mode,furthermore,the size and number of dimples decrease with the increase of stress amplitude.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2011年第6期92-100,共9页
Journal of Mechanical Engineering
关键词
涡轮盘
疲劳
损伤
断口分析
Turbine disk Fatigue Damage Fratrography
