柔性薄壁轴承的周期性冲击背景特性及其分离

Periodic impact background characteristics of flexible thin-wall bearing and its separation

柔性薄壁轴承的内外圈是椭圆,这使得它和普通滚动轴承的振动特性完全不同。这种轴承旋转过程中椭圆长短轴会对轴承造成周期性冲击,这种正常的周期性冲击和轴承元件损伤引起的故障周期性冲击混合在一起,掩盖了故障周期性冲击。分析了这种正常周期性冲击的频率分布特点,根据奇异值和频率的内在关系,提出利用奇异值分解(Singular Value Decomposition,SVD)来消除这种正常周期性冲击,选择正常周期性冲击的频率成分对应的奇异值进行SVD重构,可以准确地分离出这种正常冲击,从而消除其对故障周期性冲击的干扰。进而采用连续Morlet小波变换对消除了正常周期性冲击的柔性薄壁轴承振动信号进行故障冲击特征提取,选择峭度最大的尺度为故障特征尺度,清晰地提取到了柔性薄壁轴承的故障冲击特征,故障特征提取效果优于没有消除正常冲击时的故障特征提取效果。

The inner and outer rings of the flexible thin-wall bearing(FTB)are ellipses,and its vibration characteristics are completely different from those of the ordinary rolling bearing.The long and short axes of the ellipse will cause periodic impact on the FTB during the rotation of the bearing,this normal periodic impact and the fault periodic impact caused by the damage of the bearing elements are mixed together,and the fault periodic impact is completely masked.In this paper,the frequency distribution of the normal periodic impact is analyzed,and the singular value decomposition(SVD)is proposed to eliminate this normal periodic impact based on the intrinsic relationship between singular value and frequency.The singular values corresponding to the frequencies of the normal periodic impact are selected for SVD reconstruction,and the normal periodic impact can be accurately separated,thus eliminating its interference to the fault periodic impact.On this basis,the continuous Morlet wavelet transform is used to extract the fault impact feature of the vibration signal in which the normal periodic impact is eliminated,the fault impact feature of the FTB is clearly extracted by selecting the scale with the maximum kurtosis as the fault feature scale,and the effect is much better than that of the case in which the normal periodic impact background is not eliminated.