The Key Role of Laser Ultrasonics in the Context of Sustainable Production in an I 4.0 Value Chain

Round 1

Reviewer 1 Report

This manuscript addresses the key role of laser ultrasound techniques for online inspection, material integrity, characterization, structural health of critical parts, etc., and especially in the context and challenge of i4.0. The authors have succeeded in summarizing and describing the roadmap of the last 5-years of the main RTOs in this field, but also of several academic laboratories or pilot projects of industrial groups, in nuclear, aerospace, automotive or medical field. From the literature and regarding the national, European, or international projects carried out or in progress in this field, the interest of LUT in i4.0 and such a focus in this area is evident. Perhaps the authors could go into more detail about the various techniques that have also been successfully tested: Eddy current, DIC, IR imaging, contactless acoustic emission, OCT, ultrasound/optical spectroscopy, optical Bragg gratings, radiofrequency/magnetic sensors, embedded X-ray, etc. And more broadly, how to process the signal from these multiphysics data, or how to correlate them, digital cloud strategies, that’s a big challenge too.

Although the ms is not a scientific innovation (that is not the goal here), I can recommend the publication in Applied Science because the ms is well written and there is a good bibliography, but also the focus of LUT in i4.0 will be of interest to readers and in the scopes of AS.

Author Response

Dear Reviewer,

Thank you very much for the feedback. Enclosed are the responses to the comments.

Perhaps the authors could go into more detail about the various techniques that have also been successfully tested: Eddy current, DIC, IR imaging, contactless acoustic emission, OCT, ultrasound/optical spectroscopy, optical Bragg gratings, radiofrequency/magnetic sensors, embedded X-ray, etc.

Some of these methods have been supplemented or explained in more detail in section 3. However, several of these methods are mainly used for components that are already in service; no information could be found on their use in the production process or in subsequent quality control.

And more broadly, how to process the signal from these multiphysics data, or how to correlate them, digital cloud strategies, that’s a big challenge too.

For this purpose, some things have been added and explained in more detail. A further graphic is to represent the data processing in more detail.

Reviewer 2 Report

Please find attacthed the reviewer's report.

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

thank you very much for the feedback. Enclosed are the responses to the comments.

1. Although the title of the manuscript includes “Laser Ultrasonics”, and it is submitted to a special issue of Laser Ultrasonics in Metal Processing, the manuscript does not make a strong connection between the application of the LU and the Industry 4.0. So far, these two topics seems separate. On the one hand, all LU techniques introduced in this paper seems pretty basic and not much content are provided to show how these LU techniques are actually implemented in the industrial environment; on the other hand, this paper gives a lot about Industry 4.0 but does not really clarify how LU technology can be applied/embodied in it. In the reviewer’s opinion, more content and reference should be provided to make a clearer link between the LU technique and the Industry 4.0.

In the revised version, Section 4 goes into more detail about the importance of LUS technology in MUL 4.0. A large section has also been added to the topic of data generation and processing.

The use of an LUS system in a rolling mill for monitoring the grain size of the austenite has also been added and outlined.

 

2. There is a lot of introductory or concluding content in the text, not the least of which is something of great interest to the reviewer. However, when I want to know more about the content, I find that these contents are not marked with references. If these arguments and results are given by the authors, the corresponding arguments and proofs need to be given; if they are from other literature, the references need to be cited.

The revised version contains a lot more references to read up on. The Conclusion part includes a lot of information, which has now also been supplemented with a lot of references in the introduction. A few passages are based on experience, which are not written down, we ask for your understanding that there are no references for those.

Besides, there are some minor issues need to be addressed:

1. In Fig.1, the two reflection mirrors are placed incorrectly.

This mistake was corrected.

2. In line 411, the authors claim that “there are bulk waves on the one hand and surface waves on the other”. In fact, there are other types of waves such as lambs waves and so on.

That was rewritten as well.

Round 2

Reviewer 2 Report

The reviewer is satisfied with the improvements made by the authors therefore thinks the manuscript can be accept in its current form.