Development of a multi-component shearography instrument for surface strain measurement on dynamic objects

D. Francis; S. W. James; R. P. Tatam

doi:10.1117/12.796273

11 August 2008 Development of a multi-component shearography instrument for surface strain measurement on dynamic objects

D. Francis, S. W. James, R. P. Tatam

Author Affiliations +

Proceedings Volume 7063, Interferometry XIV: Techniques and Analysis; 706308 (2008) https://doi.org/10.1117/12.796273
Event: Optical Engineering + Applications, 2008, San Diego, California, United States

Abstract

Quantitative surface strain measurement is demonstrated on dynamic test objects using a shearography instrument comprising four measurement channels. The measurement channels are formed using four observation directions and a single illumination direction. Images from the four measurement channels are transported to a shearing interferometer using fibre-optic imaging bundles after which they are spatially multiplexed onto the quadrants of a single CCD camera. This facilitates the simultaneous acquisition of data from the four measurement channels. A pulsed laser source was used to effectively freeze the motion of the dynamic surface at two positions in its cycle. The phase variation caused by surface deformation in the time between the two recordings was calculated using the spatial carrier technique. The orthogonal displacement gradient components which characterize the surface strain of the object were calculated from the unwrapped phase maps from each measurement channel using a matrix transformation. Two test objects were investigated. The first was a thermally loaded PTFE plate rotating at 610 rpm. Images were recorded a frequency of 10 Hz, corresponding to the repetition rate of the laser. The second object was a speaker cone that was set to vibrate at frequencies in the range of 1.9-4.5 kHz. Phase measurements were made from images recorded 1.6 μs apart using dual pulsed illumination in combination with a dual-framing CCD camera.

Citation Download Citation

D. Francis, S. W. James, and R. P. Tatam "Development of a multi-component shearography instrument for surface strain measurement on dynamic objects", Proc. SPIE 7063, Interferometry XIV: Techniques and Analysis, 706308 (11 August 2008); https://doi.org/10.1117/12.796273

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
12 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Cameras

Phase measurement

Shearography

Interferometers

Composites

CCD cameras

Fringe analysis

Show All Keywords

Keywords/Phrases

Search In:

Publication Years