Cluster approach based multi-camera digital image correlation: Methodology and its application in large area high temperature measurement

• Multi-camera DIC for large area measurement without losing accuracy.
• Measures a 3D object in the universal coordinate system without data stitching.
• Detailed methodology of the proposed system is shown.
• The system shows great performance under high termperature.
• Influence factors of building a setup has been discussed.

A cluster approach based multi-camera Digital Image Correlation (DIC) system has been developed to quantify dynamic material response at temperature up to 1200 °C The Monochromatic Light Illuminated Stereo DIC technique was embedded to eliminate surface radiance at high temperature. The employed measurement system not only takes advantage of a conventional 3D DIC system, but also provides a feasible way to enlarge the measurement field without losing effective resolution in the area of interest. Two pairs of pre-calibrated CCD cameras are used to measure a piece of sheet nickel alloy. The view of each pair of cameras covers about half of the specimen. To guarantee the continuity of the evaluation result, an overlapped area that is covered by all four cameras is used in the setup. Unlike the conventional data stitching technique which stitches data from different pairs of cameras, our system with the cluster approach technique, maps all data points into a universal world coordinate system before evaluating the contour, displacement, and strain. To evaluate our system, a specimen was loaded with infrared heaters, and the dynamic contour, displacement, and strain field was evaluated. The methodology of the employed system is introduced in this paper. The system has the potential to be expanded with more cameras to measure a very large surface with one shot.