Issue 65

D. S. Lobanov et alii, Frattura ed Integrità Strutturale, 65 (2023) 74-87; DOI: 10.3221/IGF-ESIS.65.06

Р =15 kN

Р =30 kN

Moment of failure

(a)

Р =15 kN

Р =30 kN

Moment of failure

(b)

Р =15 kN

Р =30 kN

Moment of failure

(c) Figure 10: Evolution of the thermogram: a - without a defect, b - "glueline defect", square shape, c - the internal "buckling" defect of the inner layer . Based on the test results, the main mechanical properties (tensile strength, modulus of elasticity, maximum deformations during failure) were obtained and presented in Tab. 1. 95% confidence intervals were obtained using the Student's method.

No

Type of defect

Elastic modulus, GPa Tensile strength, MPa

Max load, kN

"layer buckling" defect "glueline defect", circle shape "glueline defect", square shape "glueline defect", rectangle shape

830±49 815±40 892±92 863±60 954±52

39.5±2.4 45.4±2.1 48.9±4.8 47.1±3.1 50.3±1.3

1 2 3 4 5

64.7±2.0 68.2±0.4 67.3±2.0 65.1±0.8 66.1±1.0

without a defect

Table 1: Tensile properties of CFRP specimens.

According to the tensile tests of carbon-fiber samples, the effect of the type ("glueline defect ", "buckling") and geometry (circle, square, rectangle) of the defect was assessed. According to the results of tensile tests, it was found that the "glueline defect" of any geometry in one layer does not affect the change in the mechanical properties of structural carbon-fiber

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