Evaluation of Bolt Corrosion Degree Based on Non-Destructive Testing and Neural Network

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The reviewed manuscript concerns the problem of detection and evaluation of the damages caused by corrosion of the anchor bolts immersed in concrete, rock, etc. The elastic waves and the artificial neural networks are used to deal with this. Below are several suggestions for the authors of the manuscript:

1.  Line 18 or 27, and others. In the middle of the sentence the word "anchor bolt" should be written in lowercase.

2. Line 28 or 33, and others. After the surname of the author, there is no reference to the literature.

3. Equation 9. There is no clear explanation of the symbols used in this formula.

4. Line 176. The symbol of the plane "xoz" is not clear.

5. Equations 10 - 15, These formulas are cited from some literature. Probably, they are taken from [17]. However, it is not obvious.

6. Line 195. In the text of the manuscript, there are quoted three kinds of elastic wave modes, which are present in a long bolt. They are marked as L, T, and S, while in Figure 6 there are shown the group velocities marked as L, T, and F. Moreover, in Figure 6 the title of the graph and other marks are placed using Chinese symbols.

7.  Lines 198 - 201. "From the dispersion curves, it can be observed that within the frequency range of 0-200 kHz, only one longitudinal mode can exist for the axisymmetric geometry. " This sentence is not understandable. It should be better explained.  Moreover "In the low-frequency range, the guided waves of the L(0,1) mode are non-dispersive." It is not true, because the group velocity strictly depends on the frequency as shown in Figure 6, even in the low-frequency range. Looking at Figure 6, only the mode marked as T(0,1) is non-dispersive.

8. Lines 278 -280. "The excitation signal is received at point A, the transmission end of the sensor, and at point B, the receiving end of the sensor." It is not quite clear. If I understand correctly, the input signal is generated at point A, and the elastic waves travel along the bolt, reflect from the end of the bolt, and come back to the beginning of the bolt, where the dynamic response is registered. It means that in Figures 12 and 13, the first disturbance, which is visible on the left-hand side, is the input signal with the highest amplitude. Is that correct? Moreover, it should describe, what kind of effect the corrosion has on the elastic waves (registered response), namely: amplitude reduction, change in frequency, or shift in phase of the received signal in comparison with the signal obtained from intact structure.

9. Lines 290 - 306. Generally, the question arises of what velocity is estimated: phase or group. The way how mentioned in the text of the manuscript's velocity is measured seems to be incorrect. Why the authors do not use the methods based on, for example, Hilbert transform or cross-correlation?

Taking under considerations, the above remarks I suggest a major revision of the manuscript.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

These have been highlighted in yellow and marked with comments. Please refer to the issues raised in the comments. One of the relationships does not seem correct, in terms of the sizes used or/and the units of measurement.

In the Conclusions I would like you to add some technical data, not just a descriptive part.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The reviewer has no additional comments.

Reviewer 2 Report

Comments and Suggestions for Authors

In the first version there were quite a few inconsistencies. 

At this point, since all the requirements have been resolved, I have no further comments.

 

Good luck!