scholarly journals NOVEL APPROACH TO EXTRACT DENSE FULL-FIELD DYNAMIC PARAMETERS OF LARGE-SCALE BRIDGES USING SPATIAL SEQUENCE VIDEO

2021 ◽  
Vol 27 (8) ◽  
pp. 617-636
Author(s):  
Guojun Deng ◽  
Zhixiang Zhou ◽  
Shuai Shao ◽  
Xi Chu ◽  
Peng Du
Keyword(s):  
High Speed ◽  
Field Of View ◽  
Mode Shapes ◽  
Main Beam ◽  
Dynamic Parameters ◽  
Full Field ◽  
Damage Location ◽  
Study Results ◽  
Field Dynamic ◽  
Low Order

This study proposes the use of a high-speed camera as a holographic visual sensor to obtain the dense full-field dynamic parameters of the main beam of a bridge by the field of view through uniaxial rotation photography. Based on the basic principle that the frequency and mode of a structure are inherent characteristics, the mode coordinates obtained from each field of view are unified, normalized, and matched according to the same name pixels to obtain the dense fullfield dynamic parameters of the entire bridge. The frequency and first three order modes of a self-anchored suspension test bridge are collected by the method proposed in this study. The frequency comparison between the accelerometers and dial gauges is within 3%, and the mode shapes are more holographic and more realistic than those obtained by limited measuring points. In addition, the difference in the curvature mode under various damage conditions obtained by limited measurement points is compared with that obtained by the method proposed in this study. Results shows that the dense full-field modal curvature difference can reflect the change in the damage location even in a low order, which means the sensitivity of the change of damage location in low-order modal.

Detection of Concrete Spalling Using Changes in Modal Flexibility

2010 ◽  
Vol 163-167 ◽  
pp. 2598-2602
Author(s):  
Nadia Hajihasani ◽  
Norhisham Bakhary
Keyword(s):  
Natural Frequencies ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Dynamic Parameters ◽  
Numerical Example ◽  
Damage Location ◽  
Modal Flexibility ◽  
Vibration Parameters

This paper presents a study in the effect of spalling to dynamic parameters such as natural frequencies and mode shapes. Numerical example of a slab is used as an example in this study. The slab will be modelled using ANSYS 11.0 and various types of spalling are imposed. The changes of vibration parameters are monitored and compared. To compare the sensitivity of modal parameters to spalling is determined using the flexibility method. Based on the results it is found that by incorporating mode shapes using flexibility method, damage location and severity can be obtained.

Full-field dynamic deformation and strain measurements using high-speed digital cameras

2005 ◽  
Author(s):  
Timothy E. Schmidt ◽  
John Tyson ◽  
Konstantin Galanulis ◽  
Duane M. Revilock ◽  
Matthew E. Melis
Keyword(s):  
High Speed ◽  
Dynamic Deformation ◽  
Digital Cameras ◽  
Full Field ◽  
Strain Measurements ◽  
Field Dynamic

scholarly journals A Deep Learning Framework for Damage Assessment of Composite Sandwich Structures

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Viviana Meruane ◽  
Diego Aichele ◽  
Rafael Ruiz ◽  
Enrique López Droguett
Keyword(s):  
Deep Learning ◽  
Damage Assessment ◽  
Composite Structures ◽  
High Speed ◽  
Vibration Mode ◽  
Sandwich Structures ◽  
Mode Shapes ◽  
Full Field ◽  
Composite Sandwich ◽  
Composite Sandwich Structures

The vibrational behavior of composite structures has been demonstrated as a useful feature for identifying debonding damage. The precision of the damage localization can be greatly improved by the addition of more measuring points. Therefore, full-field vibration measurements, such as those obtained using high-speed digital image correlation (DIC) techniques, are particularly useful. In this study, deep learning techniques, which have demonstrated excellent performance in image classification and segmentation, are incorporated into a novel approach for assessing damage in composite structures. This article presents a damage-assessment algorithm for composite sandwich structures that uses full-field vibration mode shapes and deep learning. First, the vibration mode shapes are identified using high-speed 3D DIC measurements. Then, Gaussian process regression is implemented to estimate the mode shape curvatures, and a baseline-free gapped smoothing method is applied to compute the damage images. The damage indices, which are represented as grayscale images, are processed using a convolutional-neural-network-based algorithm to automatically identify damaged regions. The proposed methodology is validated using numerical and experimental data from a composite sandwich panel with different damage configurations.

Application of Electronic Speckle Pattern Shearing Interferometry with High-Speed Camera in Vibration Analysis of Piezoelectric Transducer

2019 ◽  
Vol 11 (06) ◽  
pp. 1950056
Author(s):  
Hamidreza Asemani ◽  
Nasser Soltani
Keyword(s):  
Piezoelectric Transducer ◽  
Vibration Amplitude ◽  
High Speed ◽  
Speckle Pattern ◽  
Maximum Amplitude ◽  
Body Motion ◽  
Mode Shapes ◽  
High Speed Camera ◽  
Full Field ◽  
Shearing Interferometry

Electronic speckle pattern shearing interferometry, also known as shearography, is a highly sensitive technique that can measure the distribution of the displacement derivatives of the object surface. This method has also been used to describe the mode shapes of vibrating objects. In the current research, electronic speckle pattern shearing interferometry with high-speed camera was proposed for full-field measurement of the derivative of the vibration amplitude. One of the important limitations of time-average shearography is that this method is only able to provide the qualitative measurement of vibration amplitude. Stroboscopic shearography also has an inevitable limitation on the measurement of vibration amplitude at frequencies lower than 50[Formula: see text]Hz. To study the performance of shearography with high-speed camera, the research concerned the low-frequency vibration of a piezoelectric transducer during its operation. The proposed method overcomes the limitations of conventional shearography methods in quantitative measurement of vibration amplitude at low frequencies. Laser Doppler vibrometry (LDV) method was used to verify the measurement results of shearography with high-speed camera. The obtained results indicated good agreement between both shearography with high-speed camera and LDV methods. However, due to the rigid body motion of the piezoelectric transducer, LDV results generally represented more values for the maximum amplitude.

Application of High Speed Image Correlation for Measurement of Mode Shapes of a Car Bonnet

2011 ◽  
Vol 70 ◽  
pp. 45-50
Author(s):  
Thorsten Siebert ◽  
Wei Zhuo Wang ◽  
John E. Mottershead ◽  
Andrea Pipino
Keyword(s):  
High Speed ◽  
Speckle Pattern ◽  
Measurement Techniques ◽  
Image Correlation ◽  
Mode Shapes ◽  
Analysis Tool ◽  
Full Field ◽  
Digital Speckle Pattern Interferometry ◽  
Full Field Measurement ◽  
Wide Range

For the analysis of vibrations and mode shape extraction in particular the use of optical full-field measurement techniques has grown during the last years. Beside techniques like Digital Speckle Pattern Interferometry, Moiré, Thermography or Photoelasticity the Digital Image Correlation techniques have already been successfully proven to be an accurate displacement analysis tool for a wide range of applications.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

scholarly journals Spatially Resolved Experimental Modal Analysis on High-Speed Composite Rotors Using a Non-Contact, Non-Rotating Sensor

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4705
Author(s):  
Julian Lich ◽  
Tino Wollmann ◽  
Angelos Filippatos ◽  
Maik Gude ◽  
Juergen Czarske ◽  
...  
Keyword(s):  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Fiber Reinforced ◽  
Structural Dynamic ◽  
Spatially Resolved ◽  
Glass Fiber Reinforced ◽  
Vibration Responses ◽  
And Performance

Due to their lightweight properties, fiber-reinforced composites are well suited for large and fast rotating structures, such as fan blades in turbomachines. To investigate rotor safety and performance, in situ measurements of the structural dynamic behaviour must be performed during rotating conditions. An approach to measuring spatially resolved vibration responses of a rotating structure with a non-contact, non-rotating sensor is investigated here. The resulting spectra can be assigned to specific locations on the structure and have similar properties to the spectra measured with co-rotating sensors, such as strain gauges. The sampling frequency is increased by performing consecutive measurements with a constant excitation function and varying time delays. The method allows for a paradigm shift to unambiguous identification of natural frequencies and mode shapes with arbitrary rotor shapes and excitation functions without the need for co-rotating sensors. Deflection measurements on a glass fiber-reinforced polymer disk were performed with a diffraction grating-based sensor system at 40 measurement points with an uncertainty below 15 μrad and a commercial triangulation sensor at 200 measurement points at surface speeds up to 300 m/s. A rotation-induced increase of two natural frequencies was measured, and their mode shapes were derived at the corresponding rotational speeds. A strain gauge was used for validation.

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