Variable Residue Method for Modal Parameter Estimation

1995 ◽  
Vol 117 (4) ◽  
pp. 392-397
Author(s):  
R. M. Lin ◽  
M. K. Lim ◽  
K. M. Liew
Keyword(s):  
Parameter Estimation ◽  
Frequency Response Function ◽  
Modal Parameters ◽  
Practical Case ◽  
Nonlinear Structures ◽  
Modal Parameter ◽  
Engineering Structures ◽  
Data Points ◽  
Linear And Nonlinear ◽  
Modal Parameter Estimation

A new method for the estimation of modal parameters is presented in this paper. Unlike the majority of the existing methods which involve complicated curve fitting and interpolative procedures, the proposed method calculates the modal parameters by using different sets of frequency response function (FRF) data points around resonance and assumes that the residue (contribution of other modes) of the mode to be analyzed can vary with different frequency. Such features can make the proposed method be very accurate and versatile, especially in the case where modal parameters of close modes are to be identified. The method is further developed to cope with the practical case where FRF data are measured from nonlinear structures and has been found to be very effective. To demonstrate its practical applicability, the method has been applied to data measured from real engineering structures, both linear and nonlinear, and promising results have been obtained.

Simultaneous Dynamics-Based Visual Inspection Using Modal Parameter Estimation

2011 ◽  
Vol 23 (1) ◽  
pp. 180-195 ◽  
Author(s):  
Hua Yang ◽  
◽  
Takeshi Takaki ◽  
Idaku Ishii
Keyword(s):  
Parameter Estimation ◽  
Real Time ◽  
Visual Inspection ◽  
Dynamic Properties ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Modal Parameter ◽  
Resonant Frequencies ◽  
Modal Parameter Estimation ◽  
Non Destructive

In this study, we introduce the concept of dynamicsbased visual inspection with High-Frame-Rate (HFR) video analysis as a novel non-destructive active sensing method for verifying dynamic properties of a vibrating object. The HFR video is used for determining the structural dynamic properties of an object, such as its resonant frequencies and mode shapes, which can be estimated as modal parameters by modal analysis only when the object is excited. By improving and implementing a fast output-only modal parameter estimation algorithm on a real-time 2000-fps vision platform, the modal parameters of an excited object are simultaneously estimated as its input-invariant dynamic properties for dynamics-based visual inspection evenwhen the objects undergo different excitation conditions. Our simultaneous 2000-fps visual inspection system can facilitate non-destructive and longterm monitoring of the structures of beam-shaped objects vibrating at dozens or hundreds of hertz, and it can detect small changes in the dynamic properties of these objects caused by internal defects such as fatigue cracks in real time, even when their static appearances are similar. To demonstrate the performance of the proposed 2000-fps simultaneous dynamics-based visual inspection approach, the resonant frequencies and mode shapes for beam-shaped cantilevers with different artificial cracks and weights, excited by human finger tapping, were estimated in real time.

scholarly journals Operational Modal Identification of Time-Varying Structures via a Vector Multistage Recursive Approach in Hybrid Time and Frequency Domain

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Si-Da Zhou ◽  
Li Liu ◽  
Wu Yang ◽  
Zhi-Sai Ma
Keyword(s):  
Parameter Estimation ◽  
Frequency Domain ◽  
Real Time ◽  
Time Estimation ◽  
Recursive Estimation ◽  
Modal Parameters ◽  
Time Varying ◽  
Modal Parameter ◽  
Structural Dynamic ◽  
Modal Parameter Estimation

Real-time estimation of modal parameters of time-varying structures can conduct an obvious contribution to some specific applications in structural dynamic area, such as health monitoring, damage detection, and vibration control; the recursive algorithm of modal parameter estimation supplies one of fundamentals for acquiring modal parameters in real-time. This paper presents a vector multistage recursive method of modal parameter estimation for time-varying structures in hybrid time and frequency domain, including stages of recursive estimation of time-dependent power spectra, frozen-time modal parameter estimation, recursive modal validation, and continuous-time estimation of modal parameters. An experimental example validates the proposed method finally.

scholarly journals Spatial Information in Autonomous Modal Parameter Estimation

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Randall J. Allemang ◽  
Allyn W. Phillips
Keyword(s):  
Parameter Estimation ◽  
State Vector ◽  
Spatial Information ◽  
Modal Parameters ◽  
Great Promise ◽  
Consistent Estimate ◽  
Modal Parameter ◽  
Traditional Methods ◽  
Domain State ◽  
Modal Parameter Estimation

Recent work with autonomous modal parameter estimation has shown great promise in the quality of the modal parameter estimation results when compared to results from traditional methods by experienced users. While autonomous modal parameter estimation means slightly different things to different researchers and practitioners, for the purpose of this discussion, autonomous will require an automated procedure which sorts and processes a large number of possible modal parameter solutions to yield one consistent estimate with no user interaction after initial thresholds are chosen. In the work discussed, this final, consistent set of modal parameters is identifiable due to the combination of temporal and spatial information in azdomain state vector of relatively high order (5–10). Since thiszdomain state vector has both complex modal frequency and modal vector information as embedded content, sorting consistent estimates from the multitude of possible solutions is relatively trivial. Because thiszdomain state vector can be developed from the results of any modal parameter estimation method, possible solutions from different traditional methods can be utilized in the autonomous procedure to yield one consistent set of modal parameters.

scholarly journals Improved Wavelet Reassigned Scalograms and Application for Modal Parameter Estimation

2011 ◽  
Vol 18 (1-2) ◽  
pp. 299-316 ◽  
Author(s):  
Z.K. Peng ◽  
G. Meng ◽  
F. L. Chu
Keyword(s):  
Parameter Estimation ◽  
Estimation Accuracy ◽  
Modal Parameters ◽  
Modal Parameter ◽  
Comprehensive Investigation ◽  
New Methods ◽  
Frequency Components ◽  
Improvement Method ◽  
Modal Parameter Estimation ◽  
Better Than

The present work carries out a comprehensive investigation into the border distortion deficiency for the conventional scalogram and the reassigned scalogram. The reasons for this deficiency are analyzed, and a simple way is suggested to determine the border distortion ranges. New methods are proposed to reduce the border distortions in both the scalograms. The practical meanings of the border distortion improvement method are demonstrated by applying both the scalograms with and without border distortion improvements to estimate the modal parameters for a 2-DOF linear system. The estimation results indicate that, in the presence of noise, which is inevitable in practice, for the mode with weak amplitude, the reassigned scalogram can perform better than the conventional scalogram in estimating the modal parameters. In addition, for the mode with short effective duration, its frequency components at the border distortion ranges are of great importance for the modal parameter estimation purpose, and the border distortion improvement method can greatly increase the estimation accuracy.

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