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.

Study on Displacement Measurement for Induced Strain Field Based on Digital Speckle Pattern Interferometry Method

2013 ◽  
Vol 273 ◽  
pp. 510-514
Author(s):  
Jing Liu ◽  
Hui Zhang ◽  
Jun Li ◽  
Da Chuan Chen ◽  
Yan Kun Tang
Keyword(s):  
Strain Field ◽  
High Speed ◽  
Speckle Pattern ◽  
Measuring Method ◽  
Full Field ◽  
Digital Speckle Pattern Interferometry ◽  
Level Measurement ◽  
On Line ◽  
Interferometry Method ◽  
Digital Speckle

Digital Speckle Pattern Interferometry ( DSPI for short ) method has become one of the most practical worthy techniques for speckle measuring methods with the high-speed development of optic-electronical technique, image processing technology and electronic computer technology. There is a lot of advantages about it, such as uncomplicated operation, non-contacting, advanced automatic level, measurement on-line and extensive using. In this thesis, the displacement variation of the induced strain field for driving by piezoelectric ceramics can be measured by using this method. Thus we can come to a conclusion that digital speckle pattern interferometry is a new measuring method for extracting small-signal. It also provides a powerfully theoretical and experimental platform for study of automated, full-field, high-precision and nondestructive measurement.

Investigating the Flexural Behaviour of Foams at High Strain Rate Using Optical Measurement Techniques

2013 ◽  
Vol 569-570 ◽  
pp. 799-804
Author(s):  
Duncan A. Crump ◽  
Janice M. Dulieu-Barton
Keyword(s):  
High Speed ◽  
Optical Measurement ◽  
Measurement Techniques ◽  
Maximum Load ◽  
Image Correlation ◽  
Test Machine ◽  
Full Field ◽  
Closed Cell ◽  
Load To Failure ◽  
Point Bend

Polymer closed cell foam beam specimens manufactured from H100 Divinycell (Diab) are tested in four point bend at three loading speeds using a specially designed rig and an Instron VHS test machine. Synchronised high speed images are captured using white light and infra-red thermography (IRT) to obtain the mid-point full-field deflection and strains using digital image correlation (DIC) along with the temperature evolutions. There is a marked increase in the maximum load to failure with loading rate and the optical techniques provide an opportunity to analyse the strain and temperature evolution within the specimens.

scholarly journals Full Field Strain Measurement in Split Hopkinson Bar Experiments

2008 ◽  
Author(s):  
Amos Gilat ◽  
Tim Schmidt ◽  
John Tyson ◽  
Andrew Walker
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Hopkinson Bar ◽  
Image Correlation ◽  
Full Field ◽  
Split Hopkinson Bar ◽  
Strain And Strain Rate ◽  
Full Field Measurement ◽  
Split Hopkinson ◽  
Correlation System

A method for full field measurement of strain (and strain rate) in split Hopkinson bar experiments (compression, tensile, and shear) is introduced. The measurements are done by using the Aramis three-dimensional image correlation system. The system uses two digital high-speed cameras that provide a synchronized stereo view of the specimen. Depending on the number of pixels used, the system is capable or recording frames at a rate of up to about 110,000 per second. Before conducting a test, a random dot pattern is applied to the surface of the specimen. The image correlation algorithm uses the dot pattern to define a field of overlapping virtual gage boxes. The 3-D coordinates of the center of each gage box is determined at each frame, interpolated to better than 1/100 of a pixel. The coordinates are then used for calculating the deformations, strains, and strain rates throughout the surface of the specimen.

Error Estimations in Digital Image Correlation Technique

2007 ◽  
Vol 7-8 ◽  
pp. 265-270 ◽  
Author(s):  
Thorsten Siebert ◽  
Thomas Becker ◽  
Karsten Spiltthof ◽  
Isabell Neumann ◽  
Rene Krupka
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Optical Measurement ◽  
Measurement Techniques ◽  
Image Correlation ◽  
Field Analysis ◽  
Correlation Technique ◽  
Full Field ◽  
Wide Range ◽  
The Impact

The reliability for each measurement technique depends on the knowledge of it’s uncertainty and the sources of errors of the results. Among the different techniques for optical measurement techniques for full field analysis of displacements and strains, digital image correlation (DIC) has been proven to be very flexible, robust and easy to use, covering a wide range of different applications. Nevertheless the measurement results are influenced by statistical and systematical errors. We discuss a 3D digital image correlation system which provides online error information and the propagation of errors through the calculation chain to the resulting contours, displacement and strains. Performance tests for studying the impact of calibration errors on the resulting data are shown for static and dynamic applications.

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.

Tire Experimental Characterization Using Contactless Measurement Methods

2021 ◽  
Keyword(s):  
Combustion Engine ◽  
Measurement Techniques ◽  
Laser Doppler Vibrometer ◽  
Operating Conditions ◽  
Image Correlation ◽  
Optical Methods ◽  
Mode Shapes ◽  
Contactless Measurement ◽  
Full Field ◽  
Static Conditions

In the frame of automotive Noise Vibration and Harshness (NVH) evaluation, inner cabin noise is among the most important indicators. The main noise contributors can be identified in engine, suspensions, tires, powertrain, brake system, etc. With the advent of E-vehicles and the consequent absence of the Internal Combustion Engine (ICE), tire/road noise has gained more importance, particularly at mid-speed driving and in the spectrum up to 300 Hz. At the state of the art, the identification and characterization of Noise and Vibration sources rely on pointwise sensors (microphones, accelerometers, strain gauges). Optical methods such as Digital Image Correlation (DIC) and Laser Doppler Vibrometer (LDV) have recently received special attention in the NVH field because they can be used to obtain full-field measurements. Moreover, these same techniques could also allow to characterize the tire behavior in operating conditions, which would be practically impossible to derive with standard techniques. In this paper we will demonstrate how non-contact full-field measurement techniques can be used to reliably and robustly characterize the tire behavior up to 300 Hz, focusing on static conditions. Experimental modal analysis will extract the modal characteristic of the tire in both free-free and statically preloaded boundary conditions, using both DIC and LDV. The extracted natural frequencies, damping ratios and full-field mode shapes will be used on one side to improve the accuracy of tire models (either by deriving FRF based models or updating FE ones) but also as a reference for future investigation on the tire behavior characterization in rotating conditions.

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.

The Use of Modan 3D in Experimental Modal Analysis

2013 ◽  
Vol 486 ◽  
pp. 36-41 ◽  
Author(s):  
Róbert Huňady ◽  
František Trebuňa ◽  
Martin Hagara ◽  
Martin Schrötter
Keyword(s):  
Modal Analysis ◽  
Vibration Analysis ◽  
High Speed ◽  
Mechanical Vibration ◽  
Steel Sample ◽  
Experimental Modal Analysis ◽  
Image Correlation ◽  
Optical Methods ◽  
Mode Shapes ◽  
Vibration Modes

Experimental modal analysis is a relatively young part of dynamics, which deals with the vibration modes identification of machines or their parts. Its development has started since the beginning of the eighties, when the computers hardware equipment has improved and the fast Fourier transform (FFT) could be used for the results determination. Nowadays it provides an uncountable set of vibration analysis possibilities starting with conventional contact transducers of acceleration and ending with modern noncontact optical methods. In this contribution we mention the use of high-speed digital image correlation by experimental determination of mode shapes and modal frequencies. The aim of our work is to create a program application called Modan 3D enabling the performing of experimental modal analysis and operational modal analysis. In this paper the experimental modal analysis of a thin steel sample performed with Q-450 Dantec Dynamics is described. In Modan 3D the experiment data were processed and the vibration modes were determined. The reached results were verified by PULSE modulus specialized for mechanical vibration analysis.

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