Issue 21

A. Yu Fedorova et alii, Frattura ed Integrità Strutturale, 21 (2012) 46-53; DOI: 10.3221/IGF-ESIS.21.06 52 where P – tensile force (Pa), l – half-length of crack, α = 2l/h , h – width of the sample. The values of J-integrals and SIF were calculated based on the formulas (7) - (9). The results are shown in Fig. 8 and Fig. 9. a) b) Figure 8 : The dependence of J-integral versus a distance from the crack tip in the direction of crack propagation. Loading frequency is 5 Hz (a) , loading frequency - 10 Hz (b) . a) b) Figure 9 : The dependence of SIF versus a distance from the crack tip in the direction of crack propagation. Loading frequency is 5 Hz (a) , loading frequency - 10 Hz (b) . Analysis of the data presented in Fig. (8), (9) suggests that the average value of experimentally obtained SIF is approximately equal to the theoretical value of SIF at a distance from 0.4 mm to 1.2 mm from the crack tip. This allows us to use the equations (7-9) to determine the critical condition of the crack with pronounced plastic deformation zone. C ONCLUSION he effect of heat dissipation at the crack tip under cyclic loading has been studied based on the infrared thermography. To calculate the values of heat dissipation at crack tip an original data processing algorithms were developed. The algorithms include the relative motion compensation and spatial-time filtration procedures. As a T