A New Online Operational Modal Analysis Method for Vibration Control for Linear Time-Varying Structure

From the viewpoint of vibration control, if the amplitude of the main frequencies of the vibration response can be reduced, the vibration energy of the structure is greatly reduced. Modal parameters, including modal shapes, natural frequencies, and damping ratios, can reflect the dynamics of the structure and can be used to control the vibration. This paper integrates the idea of “forgetting factor weighting” into eigenvector recursive principal component analysis, and then proposes an operational modal analysis (OMA) method that uses eigenvector recursive PCA with a forgetting factor (ERPCAWF). The proposed method can identify the transient natural frequencies and transient modal shapes online and realtime using only nonstationary vibration response signals. The identified modal parameters are also suitable for online, real-time health monitoring and fault diagnosis. Finally, the modal identification results from a three-degree-of-freedom weakly damped linear time-varying structure shows that the ERPCAWF-based OMA method can effectively identify transient modal parameters online using only nonstationary response signals. The results also show that the ERPCAWF-based approach is faster, requires less memory space, and achieves higher identification accuracy and greater stability than autocorrelation matrix recursive PCA with a forgetting factor-based OMA.

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Recursive principal component analysis with forgetting factor for operational modal analysis of linear time-varying system

International Journal of Applied Electromagnetics and Mechanics ◽

10.3233/jae-162187 ◽

2016 ◽

Vol 52 (3-4) ◽

pp. 999-1006 ◽

Cited By ~ 2

Author(s):

Wei Guan ◽

Cheng Wang ◽

D.S. Chen ◽

Xiangyu Luo ◽

F.F. Su

Keyword(s):

Principal Component Analysis ◽

Modal Analysis ◽

Linear Time ◽

Principal Component ◽

Component Analysis ◽

Operational Modal Analysis ◽

Time Varying ◽

Forgetting Factor

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Identification of Historical Veziragasi Aqueduct Using the Operational Modal Analysis

The Scientific World JOURNAL ◽

10.1155/2014/518608 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 8

Author(s):

E. Ercan ◽

A. Nuhoglu

Keyword(s):

Modal Analysis ◽

Natural Frequencies ◽

Model Updating ◽

Dynamic Properties ◽

Dynamic Test ◽

Element Model ◽

Operational Modal Analysis ◽

Modal Identification ◽

Ambient Vibration ◽

Mode Shapes

This paper describes the results of a model updating study conducted on a historical aqueduct, called Veziragasi, in Turkey. The output-only modal identification results obtained from ambient vibration measurements of the structure were used to update a finite element model of the structure. For the purposes of developing a solid model of the structure, the dimensions of the structure, defects, and material degradations in the structure were determined in detail by making a measurement survey. For evaluation of the material properties of the structure, nondestructive and destructive testing methods were applied. The modal analysis of the structure was calculated by FEM. Then, a nondestructive dynamic test as well as operational modal analysis was carried out and dynamic properties were extracted. The natural frequencies and corresponding mode shapes were determined from both theoretical and experimental modal analyses and compared with each other. A good harmony was attained between mode shapes, but there were some differences between natural frequencies. The sources of the differences were introduced and the FEM model was updated by changing material parameters and boundary conditions. Finally, the real analytical model of the aqueduct was put forward and the results were discussed.

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DIC-Based Operational Modal Analysis of Bridges

Advances in Civil Engineering ◽

10.1155/2021/6694790 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Gongfa Chen ◽

Zhihua Wu ◽

Chunjian Gong ◽

Jiqiao Zhang ◽

Xiaoli Sun

Keyword(s):

Modal Analysis ◽

Natural Frequencies ◽

Operational Modal Analysis ◽

Mode Shapes ◽

Modal Parameters ◽

Small Displacement ◽

Dynamic Displacement ◽

Bridge Model ◽

Shooting Distance ◽

Dic Technique

A new method has been proposed to identify the natural frequencies and mode shapes of a bridge model, in which the digital image correlation (DIC) technique is used to track the dynamic displacement. A key issue in vibration-based damage detection for a bridge is to determine its modal parameters. It is difficult to use traditional acceleration sensors to obtain the accurate mode shapes of bridges as the sensors are only deployed on a few measurement points of the bridges. In this article, the DIC technique is used to capture the movement of the entire experimental bridge model. A steel truss is used as a bridge model and stimulated by a hammer; its dynamic displacement is recorded by using a digital video camera. The correlation analysis is used to track the displacement of the points of interest, and their displacement time histories are inputted into a modal analysis system; the natural frequencies and mode shapes of the bridge model were obtained by both operational modal analysis (OMA) and traditional experimental modal analysis (EMA) methods. (1) The DIC results are compared with those obtained by a traditional acceleration sensor-based method; the natural frequencies obtained by the two measurement methods are very close. (2) The DIC results are sensitive to the amplitude of the measured displacement and the shooting distance; small displacement amplitudes and long shooting distance may result in the low quality of the measured time-history curves, and low-frequency noise signals might be observed in their power spectral density (PSD) curves, while they can be easily solved by the filtering method in this article. (3) In addition, the first frequencies obtained by EMA and OMA are very close, which validates the applicability of the DIC measurement under ambient excitation. The research has illustrated the feasibility of the DIC method for obtaining the modal parameters of the bridges.

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Maximum likelihood estimator of operational modal analysis for linear time-varying structures in time–frequency domain

Journal of Sound and Vibration ◽

10.1016/j.jsv.2014.02.001 ◽

2014 ◽

Vol 333 (11) ◽

pp. 2339-2358 ◽

Cited By ~ 8

Author(s):

Si-Da Zhou ◽

Ward Heylen ◽

Paul Sas ◽

Li Liu

Keyword(s):

Maximum Likelihood ◽

Modal Analysis ◽

Frequency Domain ◽

Maximum Likelihood Estimator ◽

Linear Time ◽

Operational Modal Analysis ◽

Time Varying ◽

Likelihood Estimator ◽

Time Frequency

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Isomap-Based Three-Dimensional Operational Modal Analysis

Scientific Programming ◽

10.1155/2020/6348372 ◽

2020 ◽

Vol 2020 ◽

pp. 1-18

Author(s):

Cheng Wang ◽

Weihua Fu ◽

Haiyang Huang ◽

Jianwei Chen

Keyword(s):

Modal Analysis ◽

Natural Frequencies ◽

Three Dimensional ◽

Transformation Matrix ◽

Vibration Response ◽

Operational Modal Analysis ◽

Modal Parameter ◽

Matrix Assembly ◽

Random Decrement Technique ◽

Low Dimensional

In order to identify the modal parameters of time invariant three-dimensional engineering structures with damping and small nonlinearity, a novel isometric feature mapping (Isomap)-based three-dimensional operational modal analysis (OMA) method is proposed to extract nonlinear features in this paper. Using this Isomap-based OMA method, a low-dimensional embedding matrix is multiplied by a transformation matrix to obtain the original matrix. We find correspondence relationships between the low-dimensional embedding matrix and the modal coordinate response and between the transformation matrix and the modal shapes. From the low-dimensional embedding matrix, the natural frequencies can be determined using a Fourier transform and the damping ratios can be identified by the random decrement technique or natural excitation technique. The modal shapes can be estimated from the Moore–Penrose matrix inverse of the low-dimensional embedding matrix. We also discuss the effects of different parameters (i.e., number of neighbors and matrix assembly) on the results of modal parameter identification. The modal identification results from numerical simulations of the vibration response signals of a cylindrical shell under white noise excitation demonstrate that the proposed method can identify the modal shapes, natural frequencies, and ratios of three-dimensional structures in operational conditions only from the vibration response signals.

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Operational modal analysis for slow linear time-varying structures based on moving window second order blind identification

Signal Processing ◽

10.1016/j.sigpro.2016.10.016 ◽

2017 ◽

Vol 133 ◽

pp. 169-186 ◽

Cited By ~ 7

Author(s):

Cheng Wang ◽

Jianying Wang ◽

Tianshu Zhang

Keyword(s):

Modal Analysis ◽

Linear Time ◽

Second Order ◽

Operational Modal Analysis ◽

Blind Identification ◽

Time Varying ◽

Moving Window

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Operational Modal Analysis on a 3D Scaled Model of a 3-Storey Aluminium Structure

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i4.27.22485 ◽

2018 ◽

Vol 7 (4.27) ◽

pp. 78

Author(s):

M. Fadhil Shazmir ◽

N. Ayuni Safari ◽

M. Azhan Anuar ◽

A. A.Mat Isa ◽

Zamri A.R

Keyword(s):

Domain Decomposition ◽

Modal Analysis ◽

Frequency Domain ◽

Natural Frequencies ◽

Operational Modal Analysis ◽

Mode Shapes ◽

Modal Parameters ◽

Modal Assurance Criterion ◽

Scaled Model ◽

Frequency Domain Decomposition

Obtaining a good experimental modal data is essential in modal analysis in order to ensure accurate extraction of modal parameters. The parameters are compared with other extraction methods to ascertain its consistency and validity. This paper demonstrates the extraction of modal parameters using various identification algorithms in Operational Modal Analysis (OMA) on a 3D scaled model of a 3-storey aluminium structure. Algorithms such as Frequency Domain Decomposition (FDD), Enhanced Frequency Domain Decomposition (EFDD) and Stochastic Subspace Identification (SSI) are applied in this study to obtain modal parameters. The model test structure is fabricated of aluminium and assembled using bolts and nuts. Accelerometers were used to collect the responses and the commercial post processing software was used to obtain the modal parameters. The resulting natural frequencies and mode shapes using FDD method are then compared with other OMA parametric technique such as EFDD and SSI algorithm by comparing the natural frequencies and Modal Assurance Criterion (MAC). Comparison of these techniques will be shown to justify the validity of each technique used and hence confirming the accuracy of the measurement taken.

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Operational modal analysis for linear time-varying continuous dynamic structure based on LMPCA

International Journal of Applied Electromagnetics and Mechanics ◽

10.3233/jae-162085 ◽

2016 ◽

Vol 52 (1-2) ◽

pp. 701-709 ◽

Cited By ~ 1

Author(s):

Wei Guan ◽

Cheng Wang ◽

Tian Wang ◽

Huizhen Zhang ◽

Xiangyu Luo ◽

...

Keyword(s):

Modal Analysis ◽

Linear Time ◽

Dynamic Structure ◽

Operational Modal Analysis ◽

Time Varying ◽

Continuous Dynamic

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Full-Field Operational Modal Analysis of an Aircraft Composite Panel from the Dynamic Response in Multi-Impact Test

Sensors ◽

10.3390/s21051602 ◽

2021 ◽

Vol 21 (5) ◽

pp. 1602

Author(s):

Ángel Molina-Viedma ◽

Elías López-Alba ◽

Luis Felipe-Sesé ◽

Francisco Díaz

Keyword(s):

Modal Analysis ◽

Energy Absorption ◽

High Speed ◽

Operational Modal Analysis ◽

Modal Identification ◽

Image Correlation ◽

Composite Panel ◽

Impact Excitation ◽

Full Field ◽

The Impact

Experimental characterization and validation of skin components in aircraft entails multiple evaluations (structural, aerodynamic, acoustic, etc.) and expensive campaigns. They require different rigs and equipment to perform the necessary tests. Two of the main dynamic characterizations include the energy absorption under impact forcing and the identification of modal parameters through the vibration response under any broadband excitation, which also includes impacts. This work exploits the response of a stiffened aircraft composite panel submitted to a multi-impact excitation, which is intended for impact and energy absorption analysis. Based on the high stiffness of composite materials, the study worked under the assumption that the global response to the multi-impact excitation is linear with small strains, neglecting the nonlinear behavior produced by local damage generation. Then, modal identification could be performed. The vibration after the impact was measured by high-speed 3D digital image correlation and employed for full-field operational modal analysis. Multiple modes were characterized in a wide spectrum, exploiting the advantages of the full-field noninvasive techniques. These results described a consistent modal behavior of the panel along with good indicators of mode separation given by the auto modal assurance criterion (Auto-MAC). Hence, it illustrates the possibility of performing these dynamic characterizations in a single test, offering additional information while reducing time and investment during the validation of these structures.

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