Design Optimization of Sensitivity-Enhanced Structure for Fiber Bragg Grating Acoustic Emission Sensor Based on Additive Manufacturing

Round 1

Reviewer 1 Report

The manuscript “

 Design Optimization of Sensitivity-Enhanced Structure for Fi-2 ber Bragg Grating Acoustic Emission Sensor Based on 3D Printing” dealing with 3dprinting of MEX has been refereed. Please comments are listed below. The paper needs major revision. I encourage the author to read and address my comments:

1. Use ASTM 52900 for correct terminologies of AM processes.
2. Add some quantitative results to the abstract.
3. Additive manufacturing now has many advantages over conventional manufacturing. To highlight your work, add a short note in the introduction by using the following paper and mention the privilege of additive manufacturing. “Additive manufacturing a powerful tool for the aerospace industry” 2021.
4. The contribution of the paper is not clear in the current format. Highlight the contribution of the paper and make it bolder.
5. Figure 1 has no point for this paper. Please remove it.
6. What are the future directions of this research? Authors are encouraged to write the future direction.
7. Update the introduction by comparing the following new references on PLA printing with reviewed paper in your article.

• Kumar Mishra, P., S. Ponnusamy, and M.S. Reddy Nallamilli, The influence of process parameters on the impact resistance of 3D printed PLA specimens under water-absorption and heat-treated conditions.
• von Windheim, N., D.W. Collinson, T. Lau, L.C. Brinson, and K. Gall, The influence of porosity, crystallinity and interlayer adhesion on the tensile strength of 3D printed polylactic acid (PLA)
• Afonso, J.A., J.L. Alves, G. Caldas, B.P. Gouveia, L. Santana, and J. Belinha, Influence of 3D printing process parameters on the mechanical properties and mass of PLA parts and predictive models
• Gonzalez Alvarez, A., P.L. Evans, L. Dovgalski, and I. Goldsmith, Design, additive manufacture and clinical application of a patient-specific titanium implant to anatomically reconstruct a large chest wall defect.
• Travieso-Rodriguez, J.A., R. Jerez-Mesa, J. Llumà, G. Gomez-Gras, and O. Casadesus, Comparative study of the flexural properties of ABS, PLA and a PLA–wood composite manufactured through fused filament fabrication.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors present an interesting research about  acoustic emission sensor based on 3D printing and embedded FBGs to improve the sensitivity. A detailed document is well presented and discussed. I ahve some comments to be addressed. 

1. Introduction: please improve the part when is mentioned "Fiber grating sensor has the advantages of rapid response, anti-electromagnetic interference, small size, easy installation, high reliability, etc. The sensor network of distributed or quasi-distributed is easier to setup." I miss some references to highlight this part as potential simultaneous measurement when it is used single FBG element, for instance: Journal of Lightwave Technology 37 (3), 971-980, 2019; Results in Optics, 5, 2021, 100135.
2. There is no details about the FBG fabrication and details about physical length of FBG, intensity, etc. Also, from Fig. 2 seems the FBG design, in terms of physical length for normal I-shaped, more long than improved I-shaped. What is the influence to use different physical FBG length? Or do you used the same FBG length for a correct comparison between both configurations (a and b)? Please be clear about it on the document and also about details of FBG 1 and FBG2.
3. Improve some legends of figures. Some are quite basic.
4. Fig. 16: is not clear about the distance of AE source and sensing elements. Also the read color in the figure is not the best color to read.
5. Fig. 19: how many times was repeated the cycle? just one? please add more data for repeatability test. Also, Y1 and Y2 are not identified in a correct way in figure.
6. ANy type of fixation between the sensing elements to the optical table? What is the influence on it? Please comment.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The paper is ready to go.

Reviewer 2 Report

The paper was improved as suggested and clarified and can be published.