A method for full field measurement of strain (and strain rate) in split Hopkinson bar experiments (compression, tensile, and shear) is introduced. The measurements are done by using the Aramis three-dimensional image correlation system. The system uses two digital high-speed cameras that provide a synchronized stereo view of the specimen. Depending on the number of pixels used, the system is capable or recording frames at a rate of up to about 110,000 per second. Before conducting a test, a random dot pattern is applied to the surface of the specimen. The image correlation algorithm uses the dot pattern to define a field of overlapping virtual gage boxes. The 3-D coordinates of the center of each gage box is determined at each frame, interpolated to better than 1/100 of a pixel. The coordinates are then used for calculating the deformations, strains, and strain rates throughout the surface of the specimen.
Full Field Strain Measurement in Split Hopkinson Bar Experiments
Gilat, A, Schmidt, T, Tyson, J, & Walker, A. "Full Field Strain Measurement in Split Hopkinson Bar Experiments." Proceedings of the ASME 2008 9th Biennial Conference on Engineering Systems Design and Analysis. Volume 1: Advanced Energy Systems; Advanced and Digital Manufacturing; Advanced Materials; Aerospace. Haifa, Israel. July 7–9, 2008. pp. 561. ASME. https://doi.org/10.1115/ESDA2008-59198
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