PSI - Issue 54

Artur Kuchukov et al. / Procedia Structural Integrity 54 (2024) 369–375 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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tests, the durability under torsional loading was less than under tensile loading. In addition, proportional loading led to a significant red uction in the durability of the composite material. It was found that the “Proportional 1” mode was more dangerous than the “Proportional 2” mode, where the normal voltage was higher. These data were used in further studies to reduce the strength properties of fiberglass pipes. Combined tests of composite tubular samples were carried out for preliminary proportional cyclic impact with a different number of cycles and further static tension with determination of the residual Young's modulus E and tensile strength σ B . Using the “virtual extensometer” tool of the VIC -3D video system, the deformations of the working part of the sample were determined in quasi- static tensile experiments, with the help of which the secant Young’s modulus was calculated. The results obtained are presented in Table 3. The fatigue sensitivity coefficients K B and K E are defined as the ratio of the tensile strength and Young's modulus of the damaged material to their values for the undamaged material, the preliminary cyclic impact n is calculated as the ratio of the number of impact cycles to the average durability for a given exposure mode.

Table 3 Tests results Loading

N , cycle

σ B , MPa

E , GPa

n

K B

K E

0 0 0

0.000 0.000 0.000 0.273 0.545 0.818 1.091 0.279 0.559 0.838 1.118 0.165 0.330 0.495 0.659 0.824 0.239 0.477 0.716 0.955

218.3 226.5 234.3 259.9 162.9 131.1 259.6 202.2 128.3 206.0 195.1 246.2 197.4 173.7 196.9 294.0 199.3 211.9 177.6 89.6

0.964 1.001 1.035 1.148 0.720 0.579 1.147 0.893 0.567 0.910 0.862 1.088 0.872 0.767 0.396 0.870 1.299 0.880 0.936 0.785

– –

– –

20.2 13.1 12.4 13.4 15.9 17.6 16.9 19.0 16.4 17.1 16.3 12.6 14.9 20.3 16.7 15.3 17.7 –

1.000 0.649 0.614 0.663 0.787 0.871 0.837 0.941 0.812 0.847 0.807 0.624 0.738 1.005 0.827 0.757 0.876 –

Tension (T)

8051

16102 24153 32204 11989 17983 23978 5994

Torsion (To)

407 813

Proportional 1 (Pr1)

1220 1626 2033 3205 6410 9614

Proportional 2 (Pr2)

12819

The experimental dependences K B ( n ) и K E ( n ) are shown in Figure 2.