Issue 78

A. Zakharov et alii, Fracture and Structural Integrity, 78 (2026) 260-274; DOI: 10.3221/IGF-ESIS.78,16

Coupled effects of the applied stress level and the biaxial loading conditions on the J-integral and plastic SIF Coupled effects of the applied stress level and the biaxial loading conditions on the J-integral and the plastic SIF distributions are presented in Figs.5-7. Fig.5 provides the numerical results of the J-integral calculations for CCP under various biaxial loading conditions as a function of normalized stresses ( σ / σ 0 ). The upper row of Fig.5 corresponds to the CCP with the MN type crack tip. For all biaxial nominal stress states considered, the J-integral increases uniformly with applied stresses. It should be noted that for applied stress levels σ / σ 0 ≤ 0.15, the J-integral remains nearly independent of the crack-tip distance. However, when σ / σ 0 is greater than 0.15 the J-integral distributions become increasingly sensitive to the biaxial stress ratio in within the crack-tip distance range of 4*10 -3 ≥ ( r/a ) ≥ 8*10 -2 . Beyond this range, i.e., for ( r/a ) ≥ 8*10 -2 the J integral distributions are practically independent of the biaxial loading conditions and have the same values over the entire range of applied stress levels.

Figure 5: J-integral distributions as a function of applied stress level. The J-integral distributions for the CCP with the FRC crack-tip configuration are shown in the lower row of Fig. 5. In contrast to the MN case, the J-integral distributions for CCP with FRC crack tip exhibits a pronounced dependence on biaxial loading as well as the applied stress levels. Within the crack-tip distances range from r/a = 4*10 -3 to r/a = 8*10 -3 the character of the J-integral variation changes with the applied stress level. At r/a = 4*10 -3 the J-integral increases with stress level in the range 0.1 ≤ ( σ / σ 0 ) ≤ 0.3, but remains essentially constant for ( σ / σ 0 ) > 0.3 under almost all biaxial loading conditions considered. As the integration contour for the J-integral calculating is moved away from the crack tip ( r/a =

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