Experimental investigation of the spatio-temporal localization of deformation and damage in sylvinite specimens under uniaxial tension

In this work, the digital image correlation method and the acoustic emission technique are used to study the spatial-temporal localization of deformation in sylvinite under direct uniaxial tensile loading. The distribution of local strain fields over the lateral surface of the specimen subjected to quasistatic tension is analyzed. It has been found that the process of deformation in sylvinite specimens under quasi-static tension, proceeds as a sequence of two forms of spatial-temporal localization: a system of equidistant stationary areas of localized strain field and a single stationary dissipative localized structure, in which the deformation grows in an avalanche-like manner and ends in macro-fracture. The transition from one localization form to another occurs around the highest possible stress and is accompanied by a sharp decrease in the concentration parameter. The concentration parameter characterizes the degree of interaction between the defects at different scale levels through their elastic fields and can be estimated from the acoustic emission data.