PSI - Issue 50

Andrey Yu. Fedorov et al. / Procedia Structural Integrity 50 (2023) 83–90 A.Yu. Fedorov et al. / Structural Integrity Procedia 00 (2023) 000–000

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∆ l 2 is the elongation corresponding to the load F 2 , ∆ l 1 is the elongation corresponding to the load F 1 . For tensile testing, we used 4 specimens made of ebonite. The specimen was 200 mm long and had a rectangular cross-section dimensions of 18 × 15 mm. The loading rate was 1 mm / min. The results of tests are presented in Table 3.

Table 3. Determination of the elastic modulus of ebonite samples. Specimen No. Elasticity modulus E ,MPa

Average value of the elasticity modulus E a ,MPa

1 2 3 4

2062.1 2232.1 2044.6 2148.8

2121.9 ± 86.5

Tensile tests of five specimens of epoxy resin (Fig. 2b) and three specimens of P1000 material (Fig. 2c) were carried out in accordance with the GOST 11262–2017 standard on the Testometric FS100CT universal testing machine. The loading rate for specimens made of epoxy resin was 1 mm / min, and for specimens made of P1000 material it was 5mm / min. The results of tests are shown in tables 4 and 5.

Table 4. Determination of the elastic modulus of epoxy resin. Specimen No.

Elasticity modulus E ,MPa

Average value of the elasticity modulus E a ,MPa

1 2 3 4 5

2494.5 2878.1 2678.2 2716.7 2875.6

2728.6 ± 159.2

Table 5. Determination of the elastic modulus of P1000 material. Specimen No. Elasticity modulus E ,MPa

Average value of the elasticity modulus E a ,MPa

1 2 3

1.7 1.7 1.9

1.8 ± 0.1

Testing of the specimen showed that the elastic moduli of epoxy resin and ebonite are of the same order. The modulus of elasticity of the P1000 material is more than three orders of magnitude lower than the modulus of elasticity of ebonite.

3.4. Determination of tensile strength of specimens with V-notches

A tensile test was chosen as a reliable means of determining the e ff ect of the filling material on the strength of the specimens. For testing, we selected ebonite specimens in the form of bars 200 mm long with similar areas of the smallest cross sections (Fig. 1). The depth of the V-notch was 5 mm with an opening angle of 12 . 5 ◦ . The analysis of the photographs taken with a microscope made it possible to establish that the radius of rounding of the notch apex is approximately 0.05 mm. Tests were conducted for two specimens with a V-shaped notch not filled with material, two specimens filled with epoxy resin, and three specimens filled with P1000 material. The loading rate was 1 mm / min. The results of tests are shown in Table 6. The tensile test diagram for three specimens is shown in Fig. 3. When the V-shaped notch is filled with epoxy resin, there is a significant increase in the ultimate load (over 50%) for the V-shaped notch unfilled with material. When the notch is filled with material P1000, the increase in maximum force is 15%.