EMA与OMA模态参数辨识统一性方法

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振动与冲击 ›› 2016, Vol. 35 ›› Issue (12) : 7-12.

论文

EMA与OMA模态参数辨识统一性方法

董磊1，宋汉文2，郑铁生1

作者信息 +

Unity Method for EMA and OMA in Frequency Domain

DONG Lei 1??Zheng Tiesheng 1??SONG Hanwen2

Author information +

文章历史 +

摘要

现代模态测试的对象正从系统部件转向整体结构，系统的动力学特征正变得越来越复杂，表现在结构组件众多导致系统模态密集化、局部化。在实际的工程结构中，甚至无法对大型结构施加有效的激励或激励的成本很高，使得EMA方法不能进行，只能使用OMA方法。在系统动力学特征越加复杂与参数辨识难度增加的同时，对参数辨识的要求越来越高，对算法的模态辨识能力要求越来越高。EMA与OMA都面临着整体频段的拟合困难、模型阶次与模态参数选择困难以及测点数的迅速增大带来的计算量剧增等困难。并且，EMA与OMA之间还存在着辨识方法不能统一的问题。本文简要回顾了VF算法原理，并进一步将VF算法拓展到OMA问题中，将频域内的EMA与OMA建立一个统一辨识流程，实现了整个频段上的整体拟合。简化了模态参数辨识流程，减少人工介入工以及由于频段划分不当造成的识别质量的下降。利用公开数据进一步验证了EMA问题中，VF算法在低信噪比和大规模曲线数目时的辨识效果，以及在OMA问题中的良好适用性。

Abstract

The complexity of system dynamics characteristics is increasingly outstanding due to the trend of the tested objects turns from isolated components to the integral structures. Local behavior of the components and closely spaced modal increase with this complexity Exertion or measurement of the excitation is almost impossible for large-scale structures. Only the outputs is available, in which case OMA is issued. While the complexity of the system and the difficulty of analysis increasing, the higher analysis highlights current limitations of modal analysis process Several difficulties: analysis of the complete frequency band simultaneously, high system orders, the large number of measurements to be processed, exist both in EMA and OMA process. Specific mathematical models between EMA and OMA made no universal method for modal analysis. The present paper reviews the theory of VF，extends VF method to OMA. A coherent model description and Unified identification process are presented for both EMA and OMA in frequency domain. The implementation of the analysis in the whole frequency band at the same time is obtained by using a high model order (over 100), which simplify the identification process. The decrease of identification quality could be avoided by the reduction of user interaction An EMA case is discussed, which validates the VF method when it is applied to large number of FRFs (over 1000) with significant data noise. The excellent result is also confirmed in the OMA case study.

导出引用

董磊1，宋汉文2，郑铁生1. EMA与OMA模态参数辨识统一性方法[J]. 振动与冲击, 2016, 35(12): 7-12

DONG Lei 1??Zheng Tiesheng 1??SONG Hanwen2. Unity Method for EMA and OMA in Frequency Domain[J]. Journal of Vibration and Shock, 2016, 35(12): 7-12

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