Locations vs degrees of damage

Maximum of wavelet coefficients

The results of BP neural network testing

Element 20

Element 50

1 scale

2 scale

3 scale

4 scale

Predicted value

Relative error/%

10%

10%

1.561

2.483

3.438

4.575

10.032

10.013

0.32

0.13

10%

20%

1.571

2.480

3.434

4.569

9.985

19.956

−0.15

−0.22

20%

30%

1.575

2.490

3.447

4.601

20.093

30.112

0.46

0.37

20%

40%

1.595

2.484

3.439

4.591

19.926

39.993

−0.37

−0.02

30%

50%

1.60

2.493

3.452

4.626

30.012

49.883

0.04

−0.23

30%

60%

1.648

2.480

3.434

4.606

30.044

60.022

0.15

0.04

40%

70%

1.695

2.480

3.436

4.634

39.976

70.069

−0.06

0.10

40%

80%

1.813

2.439

3.381

4.678

39.980

79.992

−0.05

−0.01