Analysis of nonstationary random vibration data during lift-off
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摘要: 对飞行器助推段非平稳随机振动信号采用局部平稳模型进行分析,把此段非平稳随机信号的时变谱分解成2个独立的过程:决定时变均方值的确定性过程和决定频率特性的平稳随机过程.利用小波分析对确定性信号和随机信号进行分离,用信号的全部带宽计算非平稳信号的时变均方值,缩短了平均时间,减少了偏置误差;用信号的整个持续时间确定非平稳信号的谱特性,提高了频率分辨率,减少了随机误差.对分离出的平稳随机振动自功率谱密度进行了归纳,得到了飞行器助推段的振动环境.Abstract: The locally stationary parametric model was established to analyze the nonstationary random vibration environment of aircraft during lift-off. The computation of a time-varying spectrum was decomposed into two separate operations, one to define the time-varying mean square value of the signal, and the other to define the spectral properties of the signal. The wavelet transforms were used to separate the nonstationary vibration signal into the deterministic signal and random signal. Specifically, the time-varying mean square value of the signal was computed using the entire signal bandwidth,and the averaging time could be made short without causing a large bias error. Conversely, the basic spectra character of the signal was computed using the entire signal duration, and the frequency resolution bandwidth could be made small without causing a large random error. The vibration environment of aircraft during lift-off was obtained by concluding the auto-spectra of stationary random vibration.
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Key words:
- random vibration /
- wavelet transforms /
- nonstationary
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