基于改进HHT方法的密集模态结构参数识别

Application of an improved HHT method for modal parameters identification of structures with closely spaced modes

针对Hilbert-Huang变换(HHT)方法在识别结构模态参数中存在的经验模式分解(EMD)模态分解能力不足以及固有模式函数(IMF)分量之间不正交这2个问题,分别提出采用波组信号前处理和正交化经验模式分解的方法予以改进,并将此方法称为改进的Hilbert-Huang变换方法。在介绍正交化经验模式分解方法和波组信号前处理基本原理的基础上,给出基于此改进Hilbert-Huang变换方法识别结构模态参数的基本步骤,并通过一个具有密集模态的三自由度结构在脉冲荷载激励下的模态参数识别算例予以验证。研究结果表明:该方法可有效识别密集模态结构的模态参数,且识别效果优于基于HHT的模态参数识别方法的效果。

In the modal parameters identification proceeding using Hilbert-Huang transform（HHT） method,there exist some problems such as the deficiency of mode separation of empirical mode decomposition（EMD） and the non-othogonality between the intrinsic mode function（IMF） components.For these two problems,the improved Hilbert-Huang transform method which combined the wave group（WG） signal preceding method with the orthogonal empirical mode decomposition（OEMD） was proposed.The basic principle of OEMD and the wave group（WG） signal preceding method were introduced,and the basic procedure of modal parameters identification using the newly improved HHT method was proposed and applied in the modal parameters identification of structures.A 3-DOF structure with closely spaced modes during the impulse excitation was used to validate this method.The results show that the proposed improved HHT method can identify the modal parameters efficiently and is better than the traditional HHT method.