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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 cause of structural failure or structural failure. Aiming at the GH4133B alloy for aeroengine turbine disk, the fatigue damage and fracture mechanism are studied. The fatigue limit of GH4133B alloy was measured and the relationship between the resistance change and fatigue cycles was investigated. The experimental data were analyzed by regression and probability, and the relationship between theoretical fatigue limit and P-S-N was obtained. The damage evolution equation was characterized by the rate of resistance change. The results show that the theory of GH4133B is in good agreement with the measured fatigue limit, and the modified Chaboche damage model can predict the fatigue damage of GH4133B more accurately. The fatigue fracture was analyzed microscopically by scanning electron microscope. According to the fracture surface analysis, the source region of GH4133B is mixed fracture mode, and secondary cracks appear on the section. The extension zone presents a typical fatigue band and a brittle fatigue band can be observed at lower stress amplitudes. The instantaneous fault zone presents a quasi-brittle fracture mode, and the size and number of dimples decrease with the increase of stress amplitude.