Separation of structural modes and harmonic frequencies in Operational Modal Analysis using random decrement

2013 ◽  
Vol 41 (1-2) ◽  
pp. 366-379 ◽  
Author(s):  
S.V. Modak
Keyword(s):  
Modal Analysis ◽  
Operational Modal Analysis ◽  
Harmonic Frequencies ◽  
Random Decrement

A random decrement technique for operational modal analysis in the presence of periodic excitations

2009 ◽  
Vol 223 (7) ◽  
pp. 1525-1534 ◽  
Author(s):  
M Asayesh ◽  
B Khodabandeloo ◽  
A Siami
Keyword(s):  
White Noise ◽  
Modal Analysis ◽  
Degrees Of Freedom ◽  
Domain Decomposition Method ◽  
Gaussian White Noise ◽  
Operational Modal Analysis ◽  
Modal Parameters ◽  
Periodic Excitation ◽  
Random Decrement Technique ◽  
Random Decrement

Operational modal analysis (OMA) is a procedure that allows the identification of the modal parameters of a structure using measured responses to unknown excitation. OMA techniques are based on the assumption that the input to the structure is stationary white noise. One of the OMA techniques, which is based on the assumption of a zero mean Gaussian white noise excitation, is the random decrement (RD) technique. In many practical cases, however, periodic excitation is often present in addition to the white noise. In this study, a method based on the concept of RD transformation is proposed to extract the response of a structure to the random input from the measured response that is due to both random and periodic excitations. Applying the RD method to the extracted random response, RD signatures were estimated. Modal parameters were estimated from RD signatures using the Ibrahim time domain algorithm. It is assumed that the period of the periodic excitation is known a priori. To verify the applicability of the method, a numerical simulation of a discrete two-degrees-of-freedom (DOF) dynamic system with a viscous damping is carried out. The results of this method were also compared with the results obtained from the enhanced frequency domain decomposition method. The efficiency of the proposed method, in the cases where the frequencies of harmonic components of periodic excitation are located at the natural frequencies of the system, is also evaluated.

Response and Operational Modal Analysis from Wind Tunnel Test of the EOLO Flexible Aircraft

2021 ◽  
Author(s):  
David F. Castillo Zuñiga ◽  
Alain Giacobini Souza ◽  
Roberto G. da Silva ◽  
Luiz Carlos Sandoval Góes
Keyword(s):  
Wind Tunnel ◽  
Modal Analysis ◽  
Wind Tunnel Test ◽  
Operational Modal Analysis ◽  
Flexible Aircraft

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

Sensors ◽  
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.

scholarly journals Operational modal analysis for characterization of mechanical and thermal–hydraulic fluctuations in simulated neutron noise

2021 ◽  
Vol 373 ◽  
pp. 111017
Author(s):  
Luis Alejandro Torres Delgado ◽  
Vasudha Verma ◽  
Cristina Montalvo ◽  
Abdelhamid Dokhane ◽  
Agustín García-Berrocal
Keyword(s):  
Modal Analysis ◽  
Operational Modal Analysis ◽  
Neutron Noise

Operational modal analysis of a self-supporting antenna mast

2021 ◽  
Vol 209 ◽  
pp. 104490
Author(s):  
K. Luis García ◽  
K. Maes ◽  
V. Elena Parnás ◽  
G. Lombaert
Keyword(s):  
Modal Analysis ◽  
Operational Modal Analysis
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