Evaluation of cyclic elastoplastic strains near notches

On the basis of direct measurements of the opening displacements of notch contours, we develop an experimental-numerical procedure for the evaluation of the range of local elastoplastic strain Δε_τ. The experimental values of Δε_τ are compared with the data of numerical calculations performed by using formulas known from the literature (Δε). It is shown that, for Δε_τ(Δε)<2%, the experimental and theoretical values are in good agreement but only in the case where the gradients of strains near the tips of the notches are taken into account. For Δε_τ>2%, the theoretical values of Δε are higher than experimental Δε_τ and the smaller the radius of the notch ρ, the greater the difference between these values. Therefore, it reasonable to use the experimentally evaluated and approved values of the parameter Δε_τ. Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 33, No. 2, pp. 62–72, March–April, 1997.