High‐speed electronic speckle pattern interferometry of a struck flat plate

2008 ◽  
Vol 123 (5) ◽  
pp. 3317-3317
Author(s):  
Thomas Moore ◽  
Daniel Zietlow ◽  
Christopher Gorman
Keyword(s):  
Flat Plate ◽  
High Speed ◽  
Speckle Pattern ◽  
Electronic Speckle Pattern Interferometry

Phase Algorithm Integrating Direct-Correlation and Four-Step Phase-Shifting for Electronic Speckle Pattern Interferometry

2013 ◽  
Vol 448-453 ◽  
pp. 3696-3701
Author(s):  
Yan Bin He ◽  
Xin Zhong Li ◽  
Min Zhou
Keyword(s):  
High Speed ◽  
Speckle Pattern ◽  
Phase Shifting ◽  
Electronic Speckle Pattern Interferometry ◽  
High Speed Camera ◽  
Dynamic Measurements ◽  
High Quality ◽  
Correlation Algorithm ◽  
Phase Map

A phase-shifting algorithm, called a (4,4) algorithm, which takes four phase-shifting interferograms before a specimen is deformed and four interferograms after a specimen is deformed, is presented first. This method is most widely used for phase extraction. Its drawback limited it to be used in dynamic measurements. Also shown is an algorithm called a (4,1) algorithm that takes four phase-shifting interferograms before a specimen is deformed and one interferogram after a specimen is deformed. Because a high-speed camera can be used to record the dynamic interferogram of the specimen, this algorithm has the potential to retain the phase-shifting capability for ESPI in dynamic measurements. The quality of the phase map obtained using (4,1) algorithm is quite lower compared to using (4,4) algorithm. In order to obtain high-quality phase map in dynamic measurements, a direct-correlation algorithm was integrated with the (4,1) algorithm to form DC-(4,1) algorithm which is shown to improve significantly the quality of the phase maps. The theoretical and experimental aspects of this newly developed technique, which can extend ESPI to areas such as high-speed dynamic measurements, are examined in detail.

A study of brake disc modal behaviour during squeal generation using high-speed electronic speckle pattern interferometry and near-field sound pressure measurements

2000 ◽  
Vol 214 (3) ◽  
pp. 285-296 ◽  
Author(s):  
M Reeves ◽  
N Taylor ◽  
C Edwards ◽  
D Williams ◽  
C. H. Buckberry
Keyword(s):  
High Speed ◽  
Sound Pressure ◽  
Surface Deformation ◽  
Speckle Pattern ◽  
Near Field ◽  
Electronic Speckle Pattern Interferometry ◽  
Brake Disc ◽  
Pressure Measurements ◽  
Near Field Sound ◽  
Field Sound

The out-of-plane surface vibration of a brake disc during naturally excited squeal has been investigated using a combination of high-speed electronic speckle pattern interferometry (ESPI) and near-field sound pressure measurements. Both techniques provide visualization and quantification of the time-resolved surface velocity. A mathematical description of disc brake squeal modal behaviour is proposed that predicts accurately all of the experimentally observed interferometry and sound field measurements. The complex mode description proposed here is in agreement with that proposed by others for drum brake squeal. This assumes that two identical diametral modes are excited simultaneously, identical except for a spatial and temporal phase shift. The use of a near-field microphone array provided a convenient multipoint, non-contacting vibration probe which may find use in the study of other vibrations characterized by high surface amplitudes and efficient sound radiation. The high-speed ESPI provided a real-time visualization of surface deformation analogous to double- pulsed holographic interferometry, with the benefit of giving a true time series of the surface deformation during a single vibration cycle.

Experimental Study of Local Mass Transfer From a Flat Plate in Uniform Flow Using Electronic Speckle Pattern Interferometry

Volume 1 ◽  
2004 ◽  
Author(s):  
Tara M. Dalton ◽  
David McGuire ◽  
Mark R. Davies
Keyword(s):  
Mass Transfer ◽  
Reynolds Number ◽  
Flat Plate ◽  
Concentration Profile ◽  
Speckle Pattern ◽  
Mass Transfer Rate ◽  
Leading Edge ◽  
Field Measurements ◽  
Electronic Speckle Pattern Interferometry ◽  
Novel Approach

In this paper an investigative study of the relationship between mass and momentum transport, which have a mutual dependence, is presented. Mass transfer is an important design consideration in engineering processes such as evaporation, chemical reactions, corrosion and mixing. The effect that Reynolds number and distance from the leading edge has on mass transport from fluid to fluid interface on flat plate geometry is examined. A concentration profile is developed above a surface by passing airflow across the plate containing a well of ethanol. The rate of mass transfer is obtained from the concentration profile produced as the ethanol vapour diffuses in the airflow. Measurements are taken using the non-intrusive optical technique of Electronic Speckle Pattern Interferometry (ESPI), which has not been applied in this manner before. This novel approach offers the ability to measure in real time the mass transfer rate. A phase-shifting algorithm is also employed to give whole field measurements. The experimental results compare well to the theoretical prediction, showing that as expected the Sherwood number increases with increasing Reynolds number.

Investigative Study of Local Sherwood Numbers Using Phase Measurement Interferometry

2004 ◽  
Author(s):  
David McGuire ◽  
Tara M. Dalton ◽  
Mark R. Davies
Keyword(s):  
Mass Transfer ◽  
Flat Plate ◽  
Concentration Profile ◽  
Phase Measurement ◽  
Speckle Pattern ◽  
Momentum Transport ◽  
Electronic Speckle Pattern Interferometry ◽  
Optical Technique ◽  
Mass Transfer Equation ◽  
The Relationship

This paper investigates the relationship between mass and momentum transport. This study of mass transfer is an important design consideration when looking at engineering processes such as evaporation, chemical reactions, corrosion and mixing. Little is know about the relationship. Using the non-intrusive optical technique of Electronic Speckle Pattern Interferometry (ESPI), concentration profile measurements were carried out. A phase-shifting algorithm was also employed to give whole field measurements. Momentum transport in the velocity boundary layer was examined using Particle Image Velocimetry (PIV), which is also a non-intrusive optical technique. The two measurements were taken independently so as to reduce the effect that seed particles may have on the interferometric measurements. A concentration profile was developed above a surface by passing airflow across a flat plate containing a well of ethanol. The rate of mass transfer is obtained from the concentration profile produced as the ethanol vapour diffuses into the airflow. The experiment is set up to measure diffusion from a flat plate and to compare it with the integral solution of the mass transfer equation. Data is presented to show the dependence of the Sherwood number on the Reynolds number.

Full-Field Laser Vibrometer for Instantaneous Vibration Measurement and Non-Destructive Inspection

2010 ◽  
Vol 437 ◽  
pp. 407-411 ◽  
Author(s):  
James M. Kilpatrick ◽  
Vladimir B. Markov
Keyword(s):  
High Speed ◽  
Fiber Optic ◽  
Speckle Pattern ◽  
Vibration Measurement ◽  
Electronic Speckle Pattern Interferometry ◽  
Laser Vibrometer ◽  
Full Field ◽  
The Matrix ◽  
Interferometric Sensor ◽  
Non Destructive

We describe a system for real-time, full-field vibrometry, incorporating features of high-speed electronic speckle pattern interferometry (ESPI) and laser Doppler velocimetry (LDV). Based on a 2D interferometric sensor array, comprising 16×16 parallel illumination and detection channels, the matrix laser vibrometer (MLV), captures full-field data instantaneously, without beam scanning. The instrument design draws on the advantages of scale offered by modern telecommunications fiber optic and digital electronics. The resulting architecture, comprising a compact measurement probe linked by fiber optic umbilical to a remote electronics unit, facilitates practical application to the full-field study of transient vibrations and rapid non-destructive inspection of composite materials.

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