热声环境下燃烧室结构高频疲劳寿命评估方法

HIGH-FREQUENCY FATIGUE LIFE EVALUATION METHOD OF COMBUSTION CHAMBER STRUCTURE IN THERMAL-ACOUSTIC ENVIRONMENT

  • 摘要: 针对热声环境下发动机燃烧室结构高频疲劳寿命评估问题开展研究,基于有限元-统计能量混合方法和零阶矩应力谱法、考虑平均应力效应的Dirlik方法,提出了一种综合考虑多重热效应的结构高频疲劳寿命评估方法,进而评估了材料弹性模量、材料S-N曲线、热应力等热效应和噪声载荷对发动机燃烧室结构高频疲劳寿命的影响。研究结果表明:对于该文所研究的发动机燃烧室结构,随着温度升高,材料弹性模量的降低会使结构疲劳寿命升高;材料疲劳性能会变差,使结构疲劳寿命降低;结构热应力会增大,导致结构疲劳寿命降低。材料S-N曲线的变化对结构疲劳寿命影响程度最高,弹性模量的变化次之,热应力变化的影响较小。同时,噪声载荷量级越高,结构疲劳寿命越低。

     

    Abstract: A study was conducted on the high-frequency fatigue life evaluation of engine combustion chamber structures in thermal-acoustic environment. Based on the hybrid finite element-statistical energy analysis method, the zero-order moment stress spectrum method and the Dirlik method considering the mean stress effect, a high-frequency fatigue life evaluation method that comprehensively considers multiple thermal effects is proposed. The influence of material elastic modulus, S-N curve, thermal stress and acoustic load on the high-frequency fatigue life of the chamber structure is evaluated. The results indicate that for the engine combustion chamber structure studied in this paper, with the increase of temperature, the reduction of material elastic modulus leads to the increase of structural fatigue life. The material fatigue performance becomes worse, which result in the reduction of the structural fatigue life. While the increasing structural thermal stress leads to a decrease in the fatigue life. The change in material S-N curve has the greatest influence on the fatigue life of the structure, followed by the change of elastic modulus and the change of thermal stress. Meanwhile, the higher the level of acoustic loads, the lower the fatigue life of the structure.

     

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