透平叶片疲劳强度可靠性设计的研究

STUDY ON RELIABILITY DESIGN OF TURBINE BLADE

本文提出了透平叶片疲劳强度的可靠性设计方法。该方法把透平叶片的静应力、动应力和叶片疲劳强度处理为随机变量 ,使用疲劳应力分布和疲劳强度分布的干涉模型 ,在设计阶段确定透平叶片的可靠度。

A reliability design method is presented for fatigue strength of turbine blades.The method considers static stresses,dynamic stresses and the blade endurance strength as random variables.The scatter effects of the centrifugal tensile stress,the centrifugal bending stress and the gas bending stress are taken into consideration when the distribution parameters of static stresses are determined.The scatter effects of the static natural frequency,the dynamic natural frequency,the stimulus and the amplification factor are considered as the distribution parameters of dynamic stresses are determined.The distribution parameters of the blade endurance strength are determined under the condition that the scatter effects of the corrosion correction factor,the surface quality correction factor,the stress concentration correction factor,the dimension correction factor and the material fatigue limit are taken into account.The distribution parameters of the fatigue stress and the fatigue strength for turbine blades are obtained by the plotting method from the blade endurance strength graphs.The reliability of turbine blades can be estimated in the designing stage by use of interference models for fatigue stress distribution and fatigue strength distribution,which provides a scientific basis for designers to analyze and improve reliability of the turbine blades.