Study of the effects of stress concentration and variation of the mechanical properties

The article is focused on the comparison of two approaches to determination of the stress-strain states (SSS) and strength calculations for a thin plate with a stress concentrator in the form of a circular hole subjected to static and cyclic loading by solving the elastic problem (Kirsch problem), and also using deformation criteria of deformation and failure developed in IMASH . Using the new approach, the characteristics of the main mechanical properties, values of the rated stresses and strain fields in the stress concentration zones were varied for the first time (four calculated cases). The data analysis showed that at the sites of the cross section located near the stress concentrator, the elastoplastic stresses and strains occur already at the initial stages of loading. The stresses and strains thus determined differ greatly from those obtained using the elastic solution. The strength analysis of a thin plate with a circular hole carried out according to the strain-based criteria showed that SSS differs significantly from that obtained using the traditional elastic solution. This is true not only for the initial loading in the zone of maximum concentration (on the hole contour) but also for other points of dangerous cross-section of a specimen subjected to cyclic  loading. Using the above method one can calculate the stress and strain kinetics in the stress concentration zones (for a given plate cross section) for any loading cycle and thereby determine the stress-strain state kinetics in the concentration zones, and carry out more precise calculations of cyclic durability with allowance for the scatter of the basic mechanical properties of the structural material.

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