基于HHT方法的时变多自由度系统的损伤识别

Damage Identification of Time Varying Multi-Degrees of Freedom Systems Based on Hilbert-Huang Transform

将HHT(Hilbert-Huang Transformation,简称HHT)方法用于时变多自由度系统的损伤识别。首先对加速度响应信号进行HHT运算,得到各阶模态频率变化时程;对瞬时频率变化时程进行分析,如果频率在某时刻发生突变且随后降低,则认为该时刻系统有损伤发生;反之,则认为系统无损伤发生。数值仿真结果表明,HHT法能较好地区分时变多自由度系统的响应变化是由外激励变化引起还是由系统损伤引起,从而能根据系统响应时程信号较好地识别损伤是否发生以及发生的时刻。

The Hilbert-Huang transform(HHT) is employed to identify the damage of a time varying multi-degrees of freedom(MDOF) system.The signal is processed by HHT to obtain the instantaneous frequency of each mode,which is further used as the damage indicator to identify the onset of damage.If the instantaneous frequencies have leaps and lower,the onset of damage is diagnosed,otherwise,the system is undamaged.Numerical results show that the HHT method is capable of distinguishing the variation of response time histories of the system caused by a sudden change in excitation or a loss of structural stiffness.Thereby,it can identify whether and when the damage occurs by means of response time histories of the system.