OPERATIONAL MODAL ANALYSIS UPON ANALYTIC SECOND-ORDER BLIND IDENTIFICATION AND DISCRIMINATION BETWEEN PHYSICAL AND SPURIOUS MODES
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摘要:
自动获取运行中的模态参数对于大型土木结构的健康状态实时在线监测具有重要意义。针对现有方法模态分辨困难的问题,提出了一种基于解析二阶盲辨识的工作模态分析方法,并相应提出了真假模态区分方法以实现模态参数自动识别。与传统方法不同,该方法无需引入稳定图,可直接从结构振动响应中有效分离出各阶模态响应。通过构造模态特征指标和K均值聚类实现真假模态自动区分,并采用频域参数拟合法估计模态参数。通过8自由度数值算例和混凝土重力拱坝工程实例对该文方法效果进行了验证。结果表明:该方法具有较好的模态自动分离和筛选能力,对固有频率、阻尼比和振型的识别精度均较高,尤其对于密集模态的识别具有显著优势。
Abstract:The automated extraction of operational modal parameters is of great importance to real-time health monitoring of large infrastructures. Regarding to the shortage of the existing methods in view of the difficulty of modes discrimination, an operational modal analysis method based on analytic second-order blind identification is proposed. A companion method to discriminate between physical and spurious modes for automated identification is also developed. Unlike traditional methods, the modal responses of each mode can be separated directly from structural vibration responses without using stabilization diagrams. Physical and spurious modes can be discriminated by introducing modal metrics and adopting K-means clustering. Modal parameters can then be estimated by the frequency domain parameter fitting method. The proposed method is validated by a numerical example of 8-DOF system and an engineering example of concrete arch-gravity dam. The results show that the method has preferable ability in automated modes separation and discrimination and, demonstrates high precision in the identification of natural frequencies, of damping ratios and, of mode shapes, showing remarkable advantages, especially in the appearance of closely spaced modes.
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表 1 本文方法识别的模态参数与理论值的比较
Table 1 Comparisons between modal parameters identified by the proposed method and theoretical values
模态
阶次固有频率/Hz 阻尼比 MAC/
(%)理论值/
Hz本文方法/
Hz误差/
(%)理论值/
(%)本文方法/
(%)误差/
(%)1 2.058 2.059 0.034 2.19 2.14 2.32 99.999 2 3.325 3.326 0.024 1.35 1.42 5.84 99.998 3 4.465 4.464 −0.028 1.26 1.26 0.01 99.992 4 5.212 5.210 −0.037 1.50 1.57 4.34 99.992 表 2 EFDD识别的模态参数与理论值的比较
Table 2 Comparisons between modal parameters identified by EFDD and theoretical values
模态
阶次固有频率 阻尼比 MAC/
(%)理论值/
Hz本文方法/
Hz误差/
(%)理论值/
(%)本文方法/
(%)误差/
(%)1 2.058 2.058 0.014 2.19 2.38 8.39 99.999 2 3.325 3.326 0.022 1.35 1.25 −7.37 99.999 3 4.465 4.464 −0.039 1.26 1.23 −2.68 99.956 4 5.212 5.210 −0.011 1.50 1.18 −21.44 99.974 表 3 频域参数拟合法计算表
Table 3 Calculation table of frequency domain parameter fitting method
模态阶次 ω1 ω2 ω3 ω4 ω5 ω6 ω7 {\boldsymbol{P}}({\omega _1}) {\boldsymbol{P}}({\omega _2}) {\boldsymbol{P}}({\omega _3}) {\boldsymbol{P}}({\omega _4}) {\boldsymbol{P}}({\omega _5}) {\boldsymbol{P}}({\omega _6}) {\boldsymbol{P}}({\omega _7}) {\lambda _r} 1 18.71 19.19 19.66 20.14 20.62 21.10 21.58 0.03+0.04i 0.05+0.03i 0.06+0.02i 0.08−0.01i 0.05−0.05i 0.03−0.03i 0.02−0.03i −0.92+19.99i 2 27.34 27.82 28.30 28.78 29.26 29.74 30.22 0.02+0.04i 0.03+0.05i 0.06+0.04i 0.09+0.003i 0.06−0.03i 0.04−0.03i 0.02−0.03i −0.78+28.69i 3 37.41 37.89 38.37 38.85 39.33 39.81 40.29 0.03+0.03i 0.04+0.04i 0.06+0.03i 0.08+0.004i 0.07−0.04i 0.04−0.04i 0.03−0.04i −1.00+38.99i 4 39.33 39.81 40.29 40.77 41.25 41.73 42.21 0.01+0.03i 0.02+0.04i 0.04+0.04i 0.07+0.02i 0.06−0.01i 0.05−0.02t 0.04−0.03i −1.04+40.89i 5 50.36 50.84 51.32 51.80 52.28 52.76 53.24 0.03+0.05i 0.07+0.05i 0.08+0.02i 0.09−0.003i 0.08−0.05i 0.04−0.05i 0.03−0.04i −0.99+51.65i 注:i为虚数单位。 表 4 本文方法和EFDD方法识别的模态参数
Table 4 Modal parameters identified by the proposed method and EFDD
模态阶次 固有频率/Hz 阻尼比/(%) MAC/(%) 振型描述 本文方法 EFDD 本文方法 EFDD 1 3.185 3.184 4.60 5.62 97.98 对称 2 4.567 4.580 2.71 2.18 99.61 反对称 3 6.207 6.260 2.55 2.20 85.23 对称 4 6.510 − 2.54 − − 对称 5 8.222 8.232 1.91 1.95 98.02 反对称 -
[1] 刘宇飞, 辛克贵, 樊健生, 等. 环境激励下结构模态参数识别方法综述[J]. 工程力学, 2014, 31(4): 46 − 53. doi: 10.6052/j.issn.1000-4750.2012.11.0873 LIU Yufei, XIN Kegui, FAN Jiansheng, et al. A review of structure modal identification methods through ambient excitation [J]. Engineering Mechanics, 2014, 31(4): 46 − 53. (in Chinese) doi: 10.6052/j.issn.1000-4750.2012.11.0873
[2] PEREIRA S, REYNDERS F, MAGALHÃES F, et al. The role of modal parameters uncertainty estimation in automated modal identification, modal tracking and data normalization [J]. Engineering Structures, 2020, 224: 111208. doi: 10.1016/j.engstruct.2020.111208
[3] ZINI G, BETTI G, BARTOLI G. A quality-based automated procedure for operational modal analysis [J]. Mechanical Systems and Signal Processing, 2022, 164: 108173. doi: 10.1016/j.ymssp.2021.108173
[4] 杨志林, 罗漪, 王海峰. 基于数据库的优化随机子空间法识别精度评价[J]. 工程力学, 2023, 40(4): 116 − 128, 192. doi: 10.6052/j.issn.1000-4750.2021.10.0769 YANG Zhilin, LUO Yi, WANG Haifeng. Identification accuracy evaluation of optimized random subspace method based on database [J]. Engineering Mechanics, 2023, 40(4): 116 − 128, 192. (in Chinese) doi: 10.6052/j.issn.1000-4750.2021.10.0769
[5] 施袁锋, 朱正言, 陈鹏, 等. 基于EM算法和模态形式的状态空间模型自降阶工作模态分析[J]. 工程力学, 2021, 38(9): 15 − 25. doi: 10.6052/j.issn.1000-4750.2020.08.0618 SHI Yuanfeng, ZHU Zhengyan, CHEN Peng, et al. Operational modal analysis using EM algorithm and modal-form state-space model with auto model order reduction [J]. Engineering Mechanics, 2021, 38(9): 15 − 25. (in Chinese) doi: 10.6052/j.issn.1000-4750.2020.08.0618
[6] 何定桥, 杨军. 基于HHT的结构模态参数自动化识别方法和试验验证[J]. 工程力学, 2022, 39(11): 109 − 122. doi: 10.6052/j.issn.1000-4750.2021.06.0466 HE Dingqiao, YANG Jun. An automatic structural modal parameters identification method based on HHT and its experimental verification [J]. Engineering Mechanics, 2022, 39(11): 109 − 122. (in Chinese) doi: 10.6052/j.issn.1000-4750.2021.06.0466
[7] MAGALHÃES F, CUNHA Á, CAETANO E. Online automatic identification of the modal parameters of a long span arch bridge [J]. Mechanical Systems and Signal Processing, 2009, 23(2): 316 − 329. doi: 10.1016/j.ymssp.2008.05.003
[8] REYNDERS E, HOUBRECHTS J, DE ROECK G. Fully automated (operational) modal analysis [J]. Mechanical Systems and Signal Processing, 2012, 29: 228 − 250. doi: 10.1016/j.ymssp.2012.01.007
[9] 郑沛娟, 林迪南, 宗周红, 等. 基于图论聚类的随机子空间模态参数自动识别[J]. 东南大学学报(自然科学版), 2017, 47(4): 710 − 716. doi: 10.3969/j.issn.1001-0505.2017.04.014 ZHENG Peijuan, LIN Dinan, ZONG Zhouhong, et al. Automatic stochastic subspace identification of modal parameters based on graph clustering [J]. Journal of Southeast University (Natural Science Edition), 2017, 47(4): 710 − 716. (in Chinese) doi: 10.3969/j.issn.1001-0505.2017.04.014
[10] 张永祥, 刘心, 褚志刚, 等. 基于随机子空间法的模态参数自动提取[J]. 机械工程学报, 2018, 54(9): 187 − 194. ZHANG Yongxiang, LIU Xin, CHU Zhigang, et al. Autonomous modal parameter extraction based on stochastic subspace identification [J]. Journal of Mechanical Engineering, 2018, 54(9): 187 − 194. (in Chinese)
[11] 祝青鑫, 王浩, 茅建校, 等. 基于聚类分析的桥梁结构模态参数自动识别方法[J]. 东南大学学报(自然科学版), 2020, 50(5): 837 − 843. doi: 10.3969/j.issn.1001-0505.2020.05.007 ZHU Qingxin, WANG Hao, MAO Jianxiao, et al. Automated modal parameter identification method for bridges based on cluster analysis [J]. Journal of Southeast University (Natural Science Edition), 2020, 50(5): 837 − 843. (in Chinese) doi: 10.3969/j.issn.1001-0505.2020.05.007
[12] BELOUCHRANI A, ABED-MERAIM K, CARDOSO J F, et al. A blind source separation technique using second-order statistics [J]. IEEE Transactions on Signal Processing, 1997, 45(2): 434 − 444. doi: 10.1109/78.554307
[13] PONCELET F, KERSCHEN G, GOLINVAL J C, et al. Output-only modal analysis using blind source separation techniques [J]. Mechanical Systems and Signal Processing, 2007, 21(6): 2335 − 2358. doi: 10.1016/j.ymssp.2006.12.005
[14] MCNEIL S. An analytic formulation for blind modal identification [J]. Journal of Vibration and Control, 2011, 18(14): 2111 − 2121.
[15] LI J M, BAO T F, VENTURA C E. An automated operational modal analysis algorithm and its application to concrete dams [J]. Mechanical Systems and Signal Processing, 2022, 168: 108707. doi: 10.1016/j.ymssp.2021.108707
[16] BRINCKER R, ZHANG L M, ANDERSEN P. Modal identification of output-only systems using frequency domain decomposition [J]. Smart Material and Structures, 2001, 10(3): 441 − 445. doi: 10.1088/0964-1726/10/3/303
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