复杂载荷下轴流压气机叶片疲劳损伤数值研究
Numerical Study on the Fatigue Damage of Compressor Blade under Complex Loads

为提高叶片的服役寿命,针对压气机叶片疲劳损伤进行了数值研究。在获取叶片表面气动压力及强度分布的基础上,结合非线性连续损伤力学模型,得到叶片多级加载损伤累积方程,提出了开展结构寿命预测和损伤评估的数值计算方法。对轴流压气机叶片在典型工况转速下受离心、气动复杂载荷作用下的应力分布规律和疲劳损伤行为进行了分析。计算结果表明:叶片排气侧4％叶高处有明显的应力集中,容易发生疲劳失效;在叶片疲劳加载过程中,损伤累积速率逐渐增大,加载周期的末期易发生瞬时断裂;考虑载荷顺序对损伤累积行为的影响,和Miner线性损伤模型相比,多级加载损伤模型体现了损伤演化过程的非线性,计算结果更为准确。
In order to improve the service life of blades, the fatigue damage of compressor blade is studied by numerical method. The methods of structural fatigue life prediction and damage assessment is proposed, including blade aerodynamic pressure calculation using computational fluid dynamics (CFD), structural strength analysis based on FEM under different working conditions, and Chaboche fatigue life prediction and damage accumulation equation under multi？？level loading by nonlinear continuum damage mechanics. The fatigue damage analysis on an aero？？engine high？？pressure compressor blade is carried out by this method under aerodynamic and centrifugal loads in typical working conditions. Results indicate that the exhaustion edge in blade root has distinct stress concentration, and it is the dangerous location where fatigue failure is liable to occur. In the process of fatigue loading, the rate of damage accumulation gradually increases, and the blade fractures instantaneously in the end of the loading cycle. Considering the effect of load sequence on damage accumulation behavior, the multi？？level loading damage model can reflect the nonlinearity of damage evolution and achieve more accurate calculations compared with Miner linear damage model