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Digital Speckle Radiography (DSR) is a technique allowing full field displacement maps in a plan within an opaque material to be determined. The displacements are determined by tracking the motions of small sub-sections of a deforming speckle pattern, produced by seeding an internal layer of lead and taking flash x-ray images. An improved DSR algorithm is discussed which can improve the often poor contrast in DSR images, such that the mean and variance of the speckle pattern is uniform. This considerably improves the correlation success relative to other similar algorithms for DSR experiments. A series of experiments involving the penetration of granular media by long-rod projectiles, and the improved correlation achieved using this new algorithm, are discussed. [ABSTRACT FROM AUTHOR]

Digital Speckle Radiography (DSR), a technique allowing measurement of the full field displacement maps in a plane within an opaque material, is used to follow the temporal progression of a long-rod (100 mm long, 10 mm diameter) penetrating a granular sample at a variety of rates. Quasi-static rates of 1.5 mm/min are achieved using an Instron machine, 5 m/s is achieved using a drop-weight and velocities between 10 and 200 m/s are achieved using a light gas gun. These experiments are carried out using a series of time delayed flash x-ray images analysed with an optimised Digital Image Cross Correlation algorithm (DICC). The subsequent data sheds considerable light on the response of granular materials to penetration at a variety of rates. Particularly, a large difference in the response of the material between quasi-static and dynamic rates is observed. [ABSTRACT FROM AUTHOR]