Characterization and Finite Element Modeling of Microperforated Titanium Grade 2
Round 1
Reviewer 1 Report
Comments and Suggestions for Authorssee the attached file
Comments for author File: 
Comments.pdf
Author Response
This is a list of suggestions:
- In the introduction, Integrations of HLFC systems inside the small space of the wing leading edge” should be Integration of HLFC systems within the small space of the wing leading edge”
- The description of the tensile test specimen dimensions could be more detailed, including a labeled diagram for clarity.
- It might be helpful to include more detailed explanations of the testing equipment and methodologies for readers unfamiliar with the specific machines and standards referenced.
Corrections and further explanations have been written.
In the introduction, it is worth noting the technique of the enriched finite element method, which is used to improve the accuracy of the approximation produced by the classical finite element method. Some relevant papers are the following:
- Nudo. A general quadratic enrichment of the Crouzeix–Raviart finite element. Journal of Computational and Applied Mathematics, 451, 116112, 2024.
(and references therein)
We have included a paragraph introducing finite elements with some references.
We have not found relevant publications regarding “microperforated sheets” and “mechanical properties”. There are several publications on perforated metallic panels, but they focus on different topics, such as impact, vibrations, sound absorption, etc.
Overall, the document is well-structured and provides a comprehensive overview of the research. Minor typographical errors should be corrected, and additional explanations could enhance the clarity for a broader audience.
Thank you.
Further explanations have been included in the text.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript “Characterization and Finite Element Modeling of Microperforated Titanium Grade 2” was reviewed for possible publication in Applied Science-MDPI. Below are my recommendations and comments:
1 – I consider the manuscript relevant to the scientific community.
2 – The text has typing errors (Examples: Elastic module/elastic modulus; Titanium/titanium; μ=0.05/ μ = 0.05; ......). Check the text completely.
2 – The abstract must contain the numerical results.
3—The results obtained in this manuscript must be cited and compared with those already published. This comparison will help us understand the convergences and divergences with other published works.
4 – What is the reason for using Ti grade 2? Wouldn’t the Ti6Al4V alloy be more efficient in this application?
5 – The data are presented without experimental errors. Deviations should be included.
6 – Why does Ti-PM have a lower elastic modulus? Explain in the text.
7 – Why does Ti-PM have lower elongation? Explain in the text
8 – Who is the supplier of Ti grade 2?
9 – Did the microcracks alter the crystalline structure of Ti? Could the alpha' phase be formed?
10 – The manuscript looks like a research report, presenting results. It lacks explanations.
Comments on the Quality of English LanguageModerate editing of English language required
Author Response
The manuscript “Characterization and Finite Element Modeling of Microperforated Titanium Grade 2” was reviewed for possible publication in Applied Science-MDPI. Below are my recommendations and comments:
1 – I consider the manuscript relevant to the scientific community.
Thank you very much.
2 – The text has typing errors (Examples: Elastic module/elastic modulus; Titanium/Titanium; μ=0.05/ μ = 0.05; ......). Check the text completely.
These two types of errors have corrected. Rest of the text has been checked.
2 – The abstract must contain the numerical results.
Anisotropic ratios and elongation reduction have been added.
3—The results obtained in this manuscript must be cited and compared with those already published. This comparison will help us understand the convergences and divergences with other published works.
No relevant publications have been found. There are several publications on perforated metallic panels, but they focus on different topics, such as impact, vibrations, sound absorption, etc. In addition, the perforation patterns are so different that comparison would be complicated.
4 – What is the reason for using Ti grade 2? Wouldn’t the Ti6Al4V alloy be more efficient in this application?
Compared con Ti grade 5 (Ti6Al4V), grade 2 is cheaper, has better formability and better corrosion resistance, but it has worse mechanical properties.
Grade 2 is often used in applications where high strength is not the primary requirement, but good corrosion resistance, ductility, and cost are more important, such as outer skins.
Grade 5 is typically used in applications that require high strength, such as critical structural components, engine parts, and fasteners.
5 – The data are presented without experimental errors. Deviations should be included.
Deviations included in table 3 and commented in page 11.
6 – Why does Ti-PM have a lower elastic modulus? Explain in the text.
Commented in the text: “It can be concluded that microperforation significantly reduces the elongation and the elastic modulus. These reductions can be explained by the reduction in resistant area and the concentration of stresses caused by the holes.
7 – Why does Ti-PM have lower elongation? Explain in the text
Explained in previous question.
8 – Who is the supplier of Ti grade 2?
The base material was provided by KASTENS & KNAUER GMBH & CO. (Germany).
The microperforation was applied by Tecniker (Spain).
9 – Did the microcracks alter the crystalline structure of Ti? Could the alpha' phase be formed?
Apha case have not be found.
Microstructural aspects will be discussed in a future paper.
10 – The manuscript looks like a research report, presenting results. It lacks explanations.
Further explanations have been included in the text.
Reviewer 3 Report
Comments and Suggestions for AuthorsDear authors,
There are errors in the English language. I strongly suggest correction by a native English speaker. An example of an error:
"Present paper studies mechanical properties of micro-drilled Titanium grade 2 sheets and its modelling by Finite Element Method (FEM)."
The correct version would be: "The present paper studies the mechanical properties of micro-drilled Titanium grade 2 sheets and their modeling using the Finite Element Method (FEM)."
Another issue: there is a mix of American and British English. Here are some examples:
- American English: Modeling, Behavior
- British English: Modelling, Behaviour
Other corrections:
-
Figure 1 – include units
-
Line 102 (50 ± 3 µm). The correct format would be (50.0 ± 3.0 µm). The same applies to the line below.
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Figure 4: increase the resolution of the image (especially Figure 4b)
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Table 7: keep it on the same page
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Figure 6: what would be the explanation for the discrepancy observed between the experimental line and the finite element line (in the region of 7.5)?
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Line 251: start the sentence with a capital letter.
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Line 362: "increase a little but significantly." Wouldn't it be more formal to provide a percentage increase?
There are errors in the English language. I strongly suggest correction by a native English speaker.
Author Response
There are errors in the English language. I strongly suggest correction by a native English speaker. An example of an error:
We have reviewed and corrected the entire article.
"The present paper studies the mechanical properties of micro-drilled Titanium grade 2 sheets and their modelling by Finite Element Method (FEM)."
"The present paper studies the mechanical properties of micro-drilled Titanium grade 2 sheets and their modelling using the Finite Element Method (FEM)."
Correction made
Another issue: there is a mix of American and British English. Here are some examples:
- American English: Modelling, Behaviour
- British English: Modelling, Behaviour
Only British English is used now.
Other corrections:
- Figure 1 – include units
- Line 102 (50 ± 3 µm). The correct format would be (50.0 ± 3.0 µm). The same applies to the line below.
- Figure 4: increase the resolution of the image (especially Figure 4b)
- Table 7: keep it on the same page
Corrections made
- Figure 6: what would be the explanation for the discrepancy observed between the experimental line and the finite element line (in the region of 7.5)?
There is no displacement of the punch between 7.5 and 12.5, but there is a variation in the force. We do not have a clear explanation for this fact. Possible explanations:
- Small slippages between specimen and retainer
- Specimens present little initial buckling
The FE model produces a flat line across the range 7.5-12.5, as expected.
- Line 251: start the sentence with a capital letter.
Correction made
- Line 362: "increase a little but significantly." Wouldn't it be more formal to provide a percentage increase?
This a mistake, we do not consider “significative”. It is also explained in lines 300-305.
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsRegarding the answer to question 9, the alpha' differs from the alpha case. The α' phase is metastable with a hexagonal close-packed (HCP) crystal structure, similar to the stable alpha (α) phase. Intense plastic deformation can induce the alpha' phase (as performed in this work).
Structural and microstructural characterizations play a fundamental role in understanding the mechanical behavior of titanium alloys, which is influenced by phase changes. This understanding is essential for the study of these alloys.
A reason must be given to explain why the crystal structure of the materials was not investigated.
Author Response
Dear reviewer, thank you four your comment.
We agree that microstructure plays a fundamental role in understanding mechanical behavior. This first paper focuses on the mechanical characterization of microperforated titanium sheets, with emphasis on formability and anisotropy. The microstructural aspects, and their relationship with tensile testing and fracture, will be published in another paper shortly. We are currently working on it.
We think that including tensile testing, Nakajima testing, fracture, microstructure and FE modelling would have made the paper too long.
Best regards
