氧化铝陶瓷缺口件循环疲劳及断裂机理

用实验方法研究了Ａｌ＿２Ｏ＿３陶瓷缺口试件在循环载荷作用下的疲劳寿命。结果表明，缺口导致的应力集中效应显著降低了循环疲劳寿命；若用缺口根部最大应力为应力水平，则不同缺口半径陶瓷试件具有相同疲劳断裂规律，说明陶瓷材料的疲劳集中系数和理论应力集中系数相同。本文还分析讨论了陶瓷材料的循环疲劳寿命表达式和循环疲劳断裂机理。

CYCLIC FATIGUE LIFE OF NOTCHED ALUMINA AND CYCLIC FATIGUE MECHANISM

Cyclic fatigue testing of notched specimens of alumina wasperformed at frequency f=10￣15Hz,stress ratio R=0.15 with a sinusoidalstress wave function was applied by four-point bending.Two differentnotch radii,θ=1.5mm and ρ=0.5mm,were tested in this experiment. The test results show that cyclic life is largely reduced by stressconcentration factor.If fatigue life is correlated to the stress at notch tip,the fatigue life with different theoretical stress concentration factors arearound the same S-N curve,that is,the theoretical notch factor and fatiguenotch factor is roughly equal,The mechanism of fatigue failure is the grainboundary friction and damage evaluation of the micro cracks.