National Technology & Engineering Solutions of Sandia, LLC

Elizabeth M C Jones

Enrico C Quintana

Kathryn N Gabet Hoffmeister

Phillip L Reu

Wendy Flores-Brito

Michael M Montoya

Caroline Winters

Daniel Peter Rohe

Amanda Jones

Bryan Lee Witt

Jacob Thomas Mahaffey

Timothy J Miller

Shannon Elizabeth Murray

A method of X-ray digital image correlation is provided. The method comprises aligning cameras of an X-ray imaging system, wherein the X-ray imaging system comprises two X-ray sources pointed at a target area at a stereo angle and two corresponding X-ray detectors behind the target area. The X-ray imaging system is tuned to determine power levels of the X-ray sources that maximize image contrast and signal-to-noise ratio. The system is calibrated to determine intrinsic and extrinsic stereoscopic imaging parameters. A specimen with a random contrast pattern comprising an X-ray attenuating material is placed in the target area. Stereoscopic X-ray images are taken of the specimen and processed according to the power levels of the X-ray sources to maximize image contrast and signal-to-noise ratio and remove background objects. Kinematic quantities are determined according to changes in the contrast pattern over a number of successive images.

X-ray digital image correlation

The invention advances the ratio method of phosphor thermography using two machine vision cameras for full-field temperature measurements of a solid surface. As an example, algorithms from digital image correlation (DIC) can be used to determine the stereoscopic imaging system intrinsic and extrinsic parameters, and accurately register material points on the sample to subpixel locations in each image with 0.07 px or better accuracy. A phosphor calibration sample fabricated using aerosol deposition can be used for in situ determination of the temperature-versus-intensity ratio relationship. The full calibration methodology and several improvements on two-color phosphor thermography open the door for full-field temperature measurements in dynamic tests with deforming test specimens. In particular, thermographic phosphors can be combined with stereo digital image correlation in a novel diagnostic, TP+DIC, to measure time-resolved full-field surface strains and temperatures simultaneously, thereby enabling testing in combined thermo-mechanical environments.

Thermographic phosphor digital image correlation

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Cedar Crest, NM, United States of America

Elizabeth M C Jones