Application of Panoramic Speckle Interferometry for Testing Prismatic Porous Samples for Uniaxial Compression

The panoramic speckle interferometry method is used for registering normal displacement fields on the lateral surfaces of prismatic samples shaped as rectangular parallelepipeds under quasistatic compression in a press. The problem of vibrational disturbance is solved by fixing the base of the interferometer optical scheme on the lower frame of the press. A series of experiments are performed to register displacement kinetics on the lateral surfaces of gypsum samples when tested for longitudinal compression. The authors give an example of displacement field construction on the lateral sides of the parallelepiped and present an algorithm of dilatometric calculation for a pair of points randomly chosen on these sides. The calculation is based on the data obtained from the interferogram covering all four lateral sides of the sample due to the special arrangement of the optical scheme. The examples presented in the article show that when solid samples and samples with a through hole are subjected to gradually increasing compression, areas of possible destruction can be identified by areas of concentration of interference fringes. Areas with microcracks can be identified by ruptures in the interference fringe continuity.

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