摘要
采用气膜孔薄壁平板试样模拟冷却叶片,并与无气膜孔薄壁平板试样蠕变试验结果进行对比,研究了气膜孔对镍基单晶合金冷却叶片模拟试样高温持久断裂寿命的影响.试验结果表明:在950℃和377MPa条件下,无气膜孔薄壁平板试样的高温持久断裂寿命大约是气膜孔薄壁平板试样的2倍,扫描电镜(SEM)断口分析可以看出蠕变损伤首先发源于气膜孔周围并在气膜孔边缘开始起裂.基于晶体塑性理论建立单晶材料蠕变数值计算模型,将其编入Abaqus用户子程序中,对气膜孔和无气膜孔两种薄壁平板试样进行模拟分析.模拟结果显示在气膜孔周边存在应力集中和应力重分布,数值模拟分析结果与试样的断口表面形貌吻合.为便于工程应用,将高温持久断裂寿命与十二面体滑移系最大分切应力幅表达成指数关系,蠕变试验结果表明此式在该应力、温度条件下具有良好的精度.
Thin-walled plate specimens with cooling holes were used to model the aircooled turbine blades.Specimens without holes were employed for comparison.The effect of cooling holes on the creep life of nickel-based single crystal cooling blades was studied.Experimental results show that at 950℃,the creep lives of specimens without cooling holes are nearly twice the specimens with cooling holes when the stress is kept as 377MPa.The scanning electron microscopy（SEM）analysis on the fractured surface reveals that the creep damage stems from the local region around the holes and the ruptures initially occurs at holes edges.Based on the crystal plasticity theory,a creep model for the creep experimental data of single crystal material was developed,and implemented into the Abaqus user subroutine（UMAT）to simulate the plate specimens with and without holes.The results show thatstress concentration and redistribution occur around the cooling holes,and the form of the fracture surface is consistent well with numerical analysis.For engineering application,the relationship between the creep life and the maximum resolved shear stress amplitude of dodecahedron slip system is expressed by an exponential function.The creep test result shows that the formula has good accuracy under 950℃,377MPa.
出处
《航空动力学报》
EI
CAS
CSCD
北大核心
2014年第5期1197-1204,共8页
Journal of Aerospace Power
基金
国家自然科学基金(51175424
51210008)
西北工业大学基础研究基金(JC201238
JC201239)
西北工业大学研究生创业种子基金资助(Z2014012)
关键词
蠕变
气冷涡轮叶片
镍基单晶合金
气膜孔
薄壁平板
晶体塑性理论
creep
air-cooled turbine blades
nickel-based single crystal superalloy
cooling hole
thin-walled plate
crystal plasticity theory
