Issue 35

V. Shlyannikov et alii, Frattura ed Integrità Strutturale, 35 (2016) 114-124; DOI: 10.3221/IGF-ESIS.35.14 119 The distributions of the elastic and elastic-plastic constraint parameters along the crack front in the bending specimen under cyclic loading are plotted in Figs. 6 and 7. These distributions correspond to the crack front positions at the accumulated number of loading cycles N 1 =0 (initial front), N 2 = 28000 (intermediate front), N 3 = 38000 (intermediate front), N 4 = 44500 (final failure front). The constraint parameter is plotted against the normalized coordinate  . In this plot  = 0.0 is the crack border (the specimen free surface) while  = 1.0 is the mid-plane of the specimen thickness. It can be observed that all constraint parameters essentially changed along the crack front from the free surface toward the mid-plane. Figure 5 : Constraint parameter distributions for bending plate along crack front (1-initial, 2-3- intermediate , 4-final). Figure 6 : Elastic constraint parameter distributions along crack front under different biaxial loading conditions. The distribution of the elastic-plastic constraint parameters along the crack front in the direction from the free surface toward the mid-plane is plotted in Figs. 6 and 7 for the cruciform specimens under different biaxial loading conditions. The constraint parameters are plotted against the normalized angular coordinate  . It can be observed from these figures that all constraint parameters sufficiently changed along the crack front from the free surface toward the mid-plane as a