基于HHT的单自由度结构渐进损伤识别方法

Progressive Damage Identification of Single Degree of Freedom Structure Using Hilbert-Huang Transform

为了解决结构健康监测中非平稳随机信号的时变性并有效地监测损伤过程,研究了基于Hilbert-Huang变换的结构渐进损伤识别方法。首先,该方法模拟产生单自由度结构系统发生渐进损伤的加速度振动信号;然后对加速度振动信号进行经验模式分解,将其分解为多个平稳的固有模式函数之和;最后再选取若干个包含主要损伤信息的固有模式函数进行Hilbert变换,提取瞬时频率作为特征参数进行损伤特征提取。研究结果表明,瞬时频率可以作为结构渐进损伤的特征参数,它对损伤较敏感;损伤前后,瞬时频率会发生明显的变化。

In order to solve time-variable of a non-steady random signal during the process of structure health monitoring and identify the damage efficiently,a progressive damage identification method for the single degree of freedom(DOF)structure is studied based on Hilbert-Huang transform(HHT).Firstly,vibration acceleration signals of a single-DOF structure model were generated by reducing the stiffness gradually.Secondly,the signals were decomposed into several smooth intrinsic mode function(IMF),some IMFs which contain dominant damage information were selected and transformed by HHT.Finally,the instantaneous frequency was calculated as the feature parameter.The result indicates that the instantaneous frequency is sensitive to damages and changes obviously after the damage,which can be taken as a feature index to monitor the progressive structural damage.