READ ME File for Dataset of 'Assessment of the heterogeneous microstructure in the vicinity of a weld using thermographic measurements of the full-field dissipative heat source'

Dataset DOI: https://doi.org/10.5258/SOTON/D1775

Read Me Author: Palaniappan Jaya Seelan, University of Southampton

This dataset supports the publication:
AUTHORS: Palaniappan Jaya Seelan, Fabrice Pierron, Janice M.Dulieu-Barton
TITLE: Assessment of the heterogeneous microstructure in the vicinity of a weld using thermographic measurements of the full-field dissipative heat source
JOURNAL: Strain
DOI:10.1111/STR.12406

Raw thermal data provided in the form '.ptw' file for the following tests:

-  3 Hole-in-plate specimen tests at high spatial resolution
-  5 Laser welded specimen tests at low spatial resolution 
-  3 Laser welded specimen tests at high spatial resolution

Matlab codes are provided to obtain the results as described in the paper. It is necessary to have the following functions and calibration data provided 
in the working directory to run the codes:

- G0.5_CalibParam.mat  ==> Pixel-by-pixel calibration file for high spatial resolution
- 27mm_CalibParam.mat ==> Pixel-by-pixel calibration file for low spatial resolution
- getRoi.m/getRoi2.m ==> To select ROI from the raw thermal data
- RKF_ReadCroppedImage.m, RKF_ReadFileInfo.m, RKFLISignal.m ==> To read the '.ptw' files

Run the codes in the same working directory as the data files in the following order:

1. Calibration.m

This code performs the pixel by pixel calibration on the DL values of the raw thermal data. Dead pixels are replaced.
Enter the name of the file to be processed in line 10 e.g. 'MUBv3_385_385MPa.ptw'
Run the code
NOTE: The actuator start frame (ActuatorStartFrame) varies for each data. The codes can detect this frame automatically but occasionally returns an incorrect value. 
Typically the value is in between 1500-2000. If unsure plot s.LI (the lock-in signal) to check the frame at which the cyclic loading starts and key in the value manually if required.

2. MotionCompensation.m (Optional)

This step implements motion compensation on the thermal data and is recommended for high spatial resolution data only. 
No change required. Run code.

3. ImageProcessingPart1.m

This code prepares the 'theta' from the (motion compensated) thermal data.
No change required. Run code.
In the first pop up adjust the region of interest (ROI) selector to get the maximum are for the REFERENCE SPECIMEN. Then double click.
In the second pop up adjust the ROI selector to get the maximum area for SPECIMEN. Then double click.

4. GenerateM.m

This code generates the M matrix for image processing.
Adjust the size of the window as necessary using the variables x, y, and u.
Run the code.

5. ImageProcessingPart2.m

This code performs the final fitting procedure and calculates the dissipative heat source.
Adjust the size of the window as necessary using the variables u0, i0, and j0 consistent with the Generate.m input.
Run the code.

6. ThermoelasticSource.m

This code performs the final fitting procedure and calculates the thermoelastic heat source.
Adjust the size of the window as necessary using the variables u0, i0, and j0 consistent with the Generate.m input.
Run the code.

Date of data collection: Sep 2014 - Feb 2018

Location of data collection: Testing and Structures Research Laboratory (TSRL), University of Southampton, UK

Related projects: Innovate UK “Developing the civil nuclear power supply chain” call number 101438, Residual Stress and Structural Integrity Studies using Thermography (RESIST)

Dataset available under a CC BY 4.0 licence

Publisher: University of Southampton, U.K.

Date: March 2021