Scattered Damage Distribution in a Thin-Walled Cylinder in Biaxial Cyclic Tension

Experimental results for the damage accumulation kinetics in different strain evolution areas are presented. The major stages of scattered damage accumulation in the material on cyclic loading are examined, and the basic mechanisms of their accumulation at each loading step are described. Methods for assessing the structure of materials, including nondestructive ones, are given. This approach is a promising line of damaging parameters based on statistical estimation of a certain sample of values of the mechanical material properties. One of those parameters is the material structure homogeneity, which became the basis for the LM-hardness method. This method was used to study the distribution of scattered damages over the side surface of fractured tubular 10GN2MFA steel specimens concerning the fracture area. The specimens were cyclically loaded at different principal stress ratios. Varied cyclic loading modes led to a pronounced regular trend of increasing scattered damage levels with the approach to the fracture area. This also corresponds to an increase in residual strain levels induced by fracture. The homogeneity parameters determined on a cylindrical surface in mutually orthogonal directions correlate well. The area’s configuration for determining the structural homogeneity parameters on the surface of a structural element can greatly influence their values due to a difference in distances of the measurement points from the plastic strain localization area.