Issue 63

A. Chulkov et alii, Frattura ed Integrità Strutturale, 63 (2023) 110-121; DOI: 10.3221/IGF-ESIS.63.11

(at the speed of 5 mm/second). Black/red dots show the optimal times for defect detection in Sample 13, which was used as the reference. Note that the points out of the blue area reflect optimal observation times, which are outside of the optimal recording time of the device. However, the corresponding simulated defects can be detected at other delay times.

D1

D2

D3

D4

D5

D6

D7

D8

D9

Test parameters

Sample 1, d = 1 mm, h = 3.1 mm

τ m , s C m ,%

110 5.6

106 5.0

119 5.1

113 5.0

112 5.9

99 5.5

89 4.5

84 3.5

- -

Sample 2, d = 1 mm, h = 1 mm

τ m , s C m ,%

34

34

37

33

31

34

32

29

24 4.3

20.1

21.7

21.2

16.4

18.7

23.5

19.3

17.1

Sample 3, d = 0.5 mm, h = 3.6 mm

τ m , s

119 3.9

119 3.5

144 3.4

148 3.1

115 3.6

110 3.4

109 3.1

86 2.3

- -

C m , %

Sample 4, d = 0.5 mm, h = 1.5 mm

τ m , s C m ,%

34 9.4

37 9.9

41

39

39

39

41

34 9.0

- -

10.0

11.2

10.5

12.2

12.5

Sample 5, d = 1.5 mm, h = 2.6 mm

τ m , s C m ,%

116 7.1

111 6.7

106 6.6

102 6.5

102 7.4

86 7.2

81 6.9

75 4.8

- -

Sample 6, d = 0.1 mm, h = 4.1 mm

τ m , s C m ,%

76

67

78

74

66

66

60

49 8.8

- -

13.3

13.0

12.7

11.9

12.5

12.6

11.4

Sample 7, d = 0.1 mm, h = 2.2 mm

τ m , s C m ,%

104 1.0

160 1.3

130 1.9

130 1.3

132 1.2

114 1.3

112 1.0

80 0.7

- -

Sample 8, d = 0.3 mm, h = 3.8 mm

τ m , s C m ,%

125 3.3

131 3.4

131 2.8

124 3.0

112 3.4

120 2.9

116 2.3

94 2.0

- -

Sample 9, d = 0.3 mm, h = 1.7 mm

τ m , s C m ,%

39 8.6

38 9.4

35 8.1

39 8.2

39 8.5

38 8.7

37 8.5

36 7.3

- -

Sample 10, d = 0.3 mm, h = 2.1 mm

τ m , s C m ,%

47 5.5

49 4.9

42 5.6

51 5.5

42 5.4

43 5.8

43 5.4

37 4.1

- -

Sample 11, d = 0.3 mm, h = 4.2 mm

τ m , s C m ,%

137 2.3

143 2.6

132 2.6

180 2.0

- -

120 2.2

102 2.0

- -

- -

Sample 13**

τ m , s C m ,%

136 2.2

111 1.6

120 1.9

111 2.0

108 3.7

87 6.5

81 5.0

47 9.6

42 3.0

* These defects produce C m values below the detection threshold of 2%. ** Sample 12 contained no defects. Sample 13 contained 9 defects, the same as the other 11 samples; it was used as the reference when applying the NN for data characterization. Table 5: Optimal parameters of defect detection in Samples 1-11 and 13 ( d - defect thickness, mm) h - defect depth, mm).

116