Nonlinear Ultrasonic Detection Method for Delamination Damage of Lined Anti-Corrosion Pipes Using PZT Transducers

Round  1

Reviewer 1 Report

It is a very good work, I really enjoyed reading it. Congrats to the Authors.

I have some minor changes to suggest and three queries that must be addressed.

Corrections:

- Line 12: "Inevitably, there will be defects". Please change this statement with something weaker, e.g. "Defects may occur" .

- Line 24: "The nonlinear higher-harmonic is sensitivity to".   Shouldn't be "is sensitive to"?

- Abstract in general: please avoid any abbreviation and acronyms! Use them only starting from the Introduction section.

- Line 33: "anti-corrosion pipes are the widely used". Correct with "anti-corrosion pipes are the most widely used" and please put a reference for this strong statement.

- Line 38: Shouldn't be "and in-service" instead of "and serve"?

- Line 54-55-56: Indeed care should be taken when using active thermography over fragile and sensitive materials. However, the use of coded-excitation with low-power heating source has been demonstrated to be an effective solution in case of fragile material inspection, like cultural heritage objects. This technique is known as Pulse-Compression Thermography (PuCT). It will  be worth to mention this possibility that, however, has not been yet tried on pipelines as a possible future application. One modifying Line 54-55-56, please cite:

Tuli, S., & Mulaveesala, R. (2005). Defect detection by pulse compression in frequency modulated thermal wave imaging. Quantitative InfraRed Thermography Journal, 2(1), 41-54.

Mulaveesala, R., & Tuli, S. (2006). Theory of frequency modulated thermal wave imaging for nondestructive subsurface defect detection. Applied Physics Letters, 89(19), 191913.

Laureti, S., Sfarra, S., Malekmohammadi, H., Burrascano, P., Hutchins, D. A., Senni, L., ... & Ricci, M. (2018). The use of pulse-compression thermography for detecting defects in paintings. NDT & E International, 98, 147-154.

Laureti, S., Silipigni, G., Senni, L., Tomasello, R., Burrascano, P., & Ricci, M. (2018). Comparative study between linear and non-linear frequency-modulated pulse-compression thermography. Applied Optics, 57(18), D32-D39.

- Line 74: "method is sensitivity". Correct with "method sensitivity".

- Line 85: "by the finite element model". Correct with "by a finite element model". Also, add "analysis" to "combined the finite element analysis and nonlinear....."

- Line 96: PZT normally stand for PieZo Trasducer. So you should add Lead zirconate titanate Transducer to call them (PZT).

- Line 127: "which could use to" is "which could be used to".

- Figure 1: what is PE? I know that you specify it later but all the the abbreviation must be specified in each figure label. Please make this correction.

- Line 197: "two conditions can be considered as IMFs" should be amended as "two conditions so as to be considered as IMFs.

- Figure 4: I totally understand that T and R stands for Transmitter and Receiver transducer but please specify in the Figure caption. Same in Fig.7.

- Line 321: "the EMD was shown" should be "is shown" as you always referred to this form of past. Please do it also for other cases.

- Line 351: "To verified" is "To verify".

- Line 361: "The nonlinear coefficient was increased" should be "The nonlinear coefficient resulted being increased".

- Line 372-373: I would suggest to change in this way: "The result obtained by using WPT+HHT was found to be the best one."

- For every figure axis label: it is not a good way to specify the unit like this "damage length/mm". Unit should be put into brackets, either normal "(mm)" or straight [mm]. Please amend all the figures and all the axes.

Queries:

- Line 359: normalised to what? please specify the way in which you have normalised the signal.

- How are you sure that the nonlinearity is not due to your apparatus instead by only the delamination, i.e. transducers + amplifier? In other word, what is the effect of your amplifier to the signal recorded and shown in Fig.5?

- What is your driving signal? a toneburst at 80 kHz? please specify somewhere.

Again, nice paper.

Author Response

The authors extremely grateful for the reviewer’ comments and suggestions concerning our manuscript entitled “Nonlinear Ultrasonic Detection Method for Delamination Damage of Lined Anti-Corrosion Pipes Using PZT Transducers” (ID: applsci-383610). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval.

Special thanks to you for your good comments.

Author Response File: Author Response.pdf

Reviewer 2 Report

Extensive editing of English language and style required

Introduction should be revised significantly in terms of the research story 

There are some statements that are not quite correct such as how delamination causes problem in a structure (e.g. change of local mechanical properties)

The literature review is often too shallow and nor critical (e.g. regarding the delamination detection and previous research works)

Regarding the proposed method, the current limitations of the method should be addressed (e.g. PZT transducers are so sensitive to temperature variation so how can the method deal with the problem)

The conclusion should be more technical and summary of the outcomes. Currently it looks more like a report style.

Author Response

suggestions concerning our manuscript entitled “Nonlinear Ultrasonic Detection Method for Delamination Damage of Lined Anti-Corrosion Pipes Using PZT Transducers” (ID: applsci-383610). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. 

Special thanks to you for your good comments.

Author Response File: Author Response.pdf

Round  2

Reviewer 2 Report

The manuscript has been improved significantly and most of the points have been addressed but still English changes and proofreading seem necessary.