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高速飞行器由于其很高的飞行速度而无可避免地受到气动加热作用的影响,进而引起结构特性的时变。采用理论或有限元方法(FEM)进行数值分析,难以获取反映结构在飞行(工作)状态下的真实模态参数。通过辨识获取高速飞行器热环境下的时变结构模态参数是一项十分具有挑战性的任务。针对此问题,引入参数化时频域的最大似然方法,对气动加热作用下的高速飞行器升力面结构的时变模态参数进行了辨识。通过模拟真实飞行状态的数值算例研究,说明参数化时频域的最大似然方法能够很好地辨识出低信噪比(SNR)情况下的模态频率和模态振型,验证了参数化时频域最大似然方法适用于具有显著时变特征的高速飞行器热结构的时变结构模态参数辨识,可为将来相关的工程研究和应用提供良好的理论支持。
The high-speed aircraft is inevitably affected by the aerodynamic heating due to its high flight speed, which in turn causes the time-varying structural characteristics. Using theoretical or finite element method (FEM) for numerical analysis, it is difficult to obtain the true modal parameters reflecting the structure in flight (working) state. Obtaining the time-varying structural modal parameters under the thermal environment of high-speed aircraft through the identification is a very challenging task. In order to solve this problem, the maximum likelihood method in parametric time-frequency domain is introduced to identify the time-varying modal parameters of the lifting surface structure of a high-speed aircraft under aerodynamic heating. Numerical simulations that simulate real state of flight show that the maximum likelihood method in parametric time-frequency domain can well recognize the modal frequencies and mode shapes under low signal-to-noise ratio (SNR) The time-frequency domain maximum likelihood method is suitable for the identification of time-varying structural modal parameters of the thermal structure of a high-speed aircraft with significant time-varying features, which can provide good theoretical support for the related engineering research and application in the future.