Developments with Motion Magnification for Structural Modal Identification Through Camera Video

2015 ◽  
pp. 49-57 ◽  
Author(s):  
Justin G. Chen ◽  
Neal Wadhwa ◽  
Frédo Durand ◽  
William T. Freeman ◽  
Oral Buyukozturk
Keyword(s):  
Modal Identification ◽  
Motion Magnification

Modal identification of simple structures with high-speed video using motion magnification

2015 ◽  
Vol 345 ◽  
pp. 58-71 ◽  
Author(s):  
Justin G. Chen ◽  
Neal Wadhwa ◽  
Young-Jin Cha ◽  
Frédo Durand ◽  
William T. Freeman ◽  
...  
Keyword(s):  
High Speed ◽  
Modal Identification ◽  
High Speed Video ◽  
Motion Magnification

scholarly journals A Novel Approach for 3D-Structural Identification through Video Recording: Magnified Tracking

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1229 ◽  
Author(s):  
Yunus Harmanci ◽  
Utku Gülan ◽  
Markus Holzner ◽  
Eleni Chatzi
Keyword(s):  
Computer Vision ◽  
Motion Tracking ◽  
Video Recording ◽  
Video Camera ◽  
Diagnostic Techniques ◽  
Modal Identification ◽  
Spatial Density ◽  
Operational Conditions ◽  
Novel Approach ◽  
Motion Magnification

Advancements in optical imaging devices and computer vision algorithms allow the exploration of novel diagnostic techniques for use within engineering systems. A recent field of application lies in the adoption of such devices for non-contact vibrational response recordings of structures, allowing high spatial density measurements without the burden of heavy cabling associated with conventional technologies. This, however, is not a straightforward task due to the typically low-amplitude displacement response of structures under ambient operational conditions. A novel framework, namely Magnified Tracking (MT), is proposed herein to overcome this limitation through the synergistic use of two computer vision techniques. The recently proposed phase-based motion magnification (PBMM) framework, for amplifying motion in a video within a defined frequency band, is coupled with motion tracking by means of particle tracking velocimetry (PTV). An experimental campaign was conducted to validate a proof-of-concept, where the dynamic response of a shear frame was measured both by conventional sensors as well as a video camera setup, and cross-compared to prove the feasibility of the proposed non-contact approach. The methodology was explored both in 2D and 3D configurations, with PTV revealing a powerful tool for the measurement of perceptible motion. When MT is utilized for tracking “imperceptible” structural responses (i.e., below PTV sensitivity), via the use of PBMM around the resonant frequencies of the structure, the amplified motion reveals the operational deflection shapes, which are otherwise intractable. The modal results extracted from the magnified videos, using PTV, demonstrate MT to be a viable non-contact alternative for 3D modal identification with the benefit of a spatially dense measurement grid.

THE MODAL IDENTIFICATION METHOD IN NONLINEAR HEAT TRANSFER PROBLEMS

Equipment ◽  
2006 ◽  
Author(s):  
O. Balima ◽  
D. Petit ◽  
J. B. Saulnier ◽  
M. Girault ◽  
Y. Favennec
Keyword(s):  
Heat Transfer ◽  
Modal Identification ◽  
Identification Method ◽  
Nonlinear Heat Transfer ◽  
Transfer Problems

scholarly journals Consistent cross-modal identification of cortical neurons with coupled autoencoders

2021 ◽  
Vol 1 (2) ◽  
pp. 120-127
Author(s):  
Rohan Gala ◽  
Agata Budzillo ◽  
Fahimeh Baftizadeh ◽  
Jeremy Miller ◽  
Nathan Gouwens ◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Modal Identification

Modal characteristics and fluid–structure interaction vibration response of submerged impeller

2021 ◽  
pp. 107754632110036
Author(s):  
Shihui Huo ◽  
Hong Huang ◽  
Daoqiong Huang ◽  
Zhanyi Liu ◽  
Hui Chen
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Damping Ratio ◽  
Pure Water ◽  
Vibration Response ◽  
Modal Identification ◽  
Liquid Oxygen ◽  
Modal Characteristics ◽  
Oxygen Pump ◽  
Turbo Pump

Turbo pump is one of the elements with the most complex flow of liquid rocket engine, and as an important component of turbo pump, an impeller is the weak point affecting its reliability. In this study, a noncontact modal characteristic identification technique was proposed for the liquid oxygen pump impeller. Modal characteristics of the impeller under three different submerged media, air, pure water, and brine with same density as liquid oxygen, were tested based on the noncontact modal identification technology. Submersion state directly affects the modal frequencies and damping ratio. The transient vibration response characteristics of the impeller excited by the unsteady flow field was achieved combining with unsteady flow field analysis and transient dynamic analysis in the whole flow passage of the liquid oxygen pump. Vibration responses at different positions of the impeller show 10X and 20X frequencies, and the amplitude at the root of short blade is significant, which needs to be paid more attention in structural design and fatigue evaluation.

Modal identification of concrete arch dam by fully automated operational modal identification

Structures ◽  
2021 ◽  
Vol 32 ◽  
pp. 228-236
Author(s):  
Hasan Mostafaei ◽  
Mehdi Ghamami ◽  
Pegah Aghabozorgi
Keyword(s):  
Arch Dam ◽  
Modal Identification ◽  
Concrete Arch Dam

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.

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