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H. Bai et alii, Frattura ed Integrità Strutturale, 56 (2021) 16-45; DOI: 10.3221/IGF-ESIS.56.02

Crack initiation stress of crack ①

Crack initiation stress of crack ②

Average value of crack initiation stress

Number

G1

0.61

0.71

0.66

G2

0.78

0.72

0.75

G3

0.82

0.94

0.88

G4

1.07

1.11

1.09

G5

1.38

1.34

1.36

Table 9: Crack initiation stress of ductile group (MPa).

Crack initiation stress of crack ①

Crack initiation stress of crack ②

Average value of crack initiation stress

Number

H1

0.63

0.55

0.59

H2

0.86

0.76

0.81

H3

0.93

0.97

0.95

H4

1.11

1.13

1.12

H5

1.19

1.15

1.17

Table 10: Crack initiation stress of brittle group (MPa).

1.4

1.6

crack ① crack ②

1.4

1.2

1.2

1.0

1.0

crack ① crack ②

0.8

0.8

0.6

0.6

Crack initiation stress (MPa)

Crack initiation stress (MPa)

0.4

0.4

1.0

1.5

2.0

2.5

3.0

3.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Content of epoxide resin and polyamide (%)

Rosin content (%)

Figure 16: The crack initiation stress of two cracks in specimens.

Analysis of peak strain ① Peak strain of ductile group

The peak strain of the specimen with different epoxide resin-polyamide content was obtained by processing the experiment data, as shown in Tab. 11. The relationship between the peak strain of the specimen and the content of epoxide resin polyamide is shown in Fig. 17. It can be seen from the figure that the minimum peak strain of the specimen is 0.80% and the maximum peak strain is 1.55%. Therefore, it can be considered that the change of the content of epoxide resin-polyamide has a relatively striking influence on the peak strain of the specimen. At the same time, with the increase of epoxide resin-polyamide content, the

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