Experimental verification of full-field accuracy in stereo-DIC based on the ESPI method

Area of Science:

• Optical Measurement Techniques
• Experimental Mechanics
• Metrology

Background:

• Accurate full-field displacement measurement is crucial in experimental mechanics.
• Digital Image Correlation (DIC) and Electronic Speckle Pattern Interferometry (ESPI) are powerful optical methods.
• Integrating DIC and ESPI can overcome individual limitations and enhance measurement capabilities.

Purpose of the Study:

• To propose and validate a method for merging stereo-DIC and ESPI data through camera calibration.
• To verify the accuracy of full-field out-of-plane displacements measured by stereo-DIC.
• To enable high-precision 3D deformation measurements by unifying coordinate systems of multiple ESPI systems.

Main Methods:

• Camera calibration to merge stereo-DIC and ESPI data.
• Cantilever beam test to evaluate full-field out-of-plane displacement accuracy.
• Analysis of mean absolute error and Root Mean Square Error (RMSE) for displacement measurements.

Main Results:

• Stereo-DIC achieved high accuracy with RMSE of 1.08 µm (60 mm FOV) and 1.48 µm (120 mm FOV).
• Calibration errors influenced displacement accuracy, showing non-uniform distribution at 60 mm FOV.
• The method successfully traced stereo-DIC accuracies to laser wavelength, confirming data integrity.

Conclusions:

• The proposed merging method accurately verifies stereo-DIC measurements and determines rigid-body displacement for ESPI.
• This integration allows for high-precision 3D deformation measurements over large ranges by unifying multiple ESPI systems.
• The technique offers a robust solution for advanced experimental mechanics and metrology applications.