Issue 71

D. S. Lobanov et alii, Fracture and Structural Integrity, 71 (2025) 1-10; DOI: 10.3221/IGF-ESIS.71.01

of specimens were used as the ultimate strength (see Tab. 1). The failure criterion was defined as either a 50% reduction in maximum load from cycle to cycle or the destruction of the specimen into parts.

a b Figure 1: Scheme of specimens ( a) with internal defects ( b ) "dry-spot" and "winkles" [25].

Maximum load, kN

Maximum stress, MPa

Defect

Without defect Dry-spot, a circle

26.1 25.9 23.8

801 801

Wrinkles 712 Table 1: Results of static tensile tests of CFRP specimens.

№

Defect

σ / σ в

Waveform cycle

R

1 2 3 4 5 6 7 8 9

Without defect Without defect Without defect Without defect Without defect Without defect

triangle triangle triangle

0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

0.56 0.64 0.44 0.48 0.56 0.44 0.56 0.64 0.75 0.70 0.64 0.75 0.70 0.70 0.65 0.70 0.75 0.70 0.75 0.65

sinus sinus sinus sinus sinus sinus sinus

Dry-spot Dry-spot Dry-spot Dry-spot Dry-spot Dry-spot Dry-spot Dry-spot Wrinkles Wrinkles Wrinkles Wrinkles Wrinkles Wrinkles

10 11 12 13 14 15 16 17 18 19 20

triangle triangle triangle triangle

sinus sinus sinus

triangle triangle triangle

Table 2: Loading parameters of specimens.

3