Theoretical Analysis of Plastic Behavior of Sandwich Beam with Metal Foam under Repeated Impacts
Round 1
Reviewer 1 Report
The review entitled "Theoretical analysis on plastic behavior of sandwich beam with metal foam under repeated impacts” established a theoretical model to analyze the plastic mechanical behavior of MFSBs suffering from repeated impacts, in which the Membrane Factor Method is applied to derive the analytical solutions for the plastic responses of MFSBs.
This manuscript is well-written and provides valuable theoretical analysis. The manuscript can be accepted after considering the following comments:
Comments:
1- The author should increase their discussion on previous related research and highlight how their study is providing a different approach or adding significantly to what has been done.
2- The abbreviations should be defined at the first call in the text and then they can be used. For example, what is the meaning of “MFSBs”?
3- Did the authors consider the slip interaction between the three layers? The authors need to provide the assumptions that were assumed in the developed analytical model.
4- It is recommended to provide a flowchart that summarize the sequence of the developed analytical model.
5- Line 131: What is the meaning of this expression "h/(c+2t)?
6- Figure 1(b): The dimension “h” is not accurate in this figure.
Author Response
We are very grateful to your and the reviewers’ critical comments and thoughtful suggestions about our manuscript. The responses to reviewer's comment have been finished, please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
In this manuscript authors show theoretical analysis on plastic behavior of sandwich beam with metal foam under repeated impacts. The information showed in the manuscript could be interesting. However, there are some points which the authors should improve:
1. The information showed in this manuscript are very similar to authors previous works
2. The auto-citation level is too high – authors should improve it
My recommendation is major revision
Regards
Author Response
We are very grateful to your and the reviewers’ critical comments and thoughtful suggestions about our manuscript. The responses to reviewer's comment have been finished, please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 3 Report
Authors stated the theoretical analysis on plastic behavior of sandwich beam with metal foam under repeated impacts, however it seems many of publications are available as descried. Also reference 30 & 31 are belongs similar theme only minor concept has been implemented. Moreover the authors needs to add few experimental data and to be validated with theoretical and experimental results, as they discussed in earlier proof of concept.
Authors stated the theoretical analysis on plastic behavior of sandwich beam with metal foam under repeated impacts, however it seems many of publications are available as descried. Also reference 30 & 31 are belongs similar theme only minor concept has been implemented. Moreover the authors needs to add few experimental data and to be validated with theoretical and experimental results, as they discussed in earlier proof of concept.
Author Response
We are very grateful to your and the reviewers’ critical comments and thoughtful suggestions about our manuscript. The responses to reviewer's comment have been finished, please see the attachment.
Author Response File: Author Response.pdf
Reviewer 4 Report
Presented problem considering the very useful problem of composite structure subjected to repeated impacts has great practical and scientific meaning.
Manuscript is very well organized and in my opinion is worth publishing.
I propose to emphasize the new and original elements of the presented problem. In conclusion, further investigations should be indicated.
Some doubt is connected with the cross-section deformation of the sandwich structure. It can be linear, classical broken line or nonlinear. Some comments rather should be presented.
Author Response
We are very grateful to your and the reviewers’ critical comments and thoughtful suggestions about our manuscript. The responses to reviewer's comment have been finished, please see the attachment.
Author Response File: Author Response.docx
Reviewer 5 Report
Based on the rigid-plastic assumption, the theoretical model is established to analyze the plastic mechanical behavior of MFSBs suffering from repeated impacts, in which the Membrane Factor Method (MFM) is applied to derive the analytical solutions for the plastic responses of MFSBs. The theoretical predictions agree well with the results of impact tests and numerical simulations. Besides, the dynamic responses of MFSBs are analyzed based on MFM, and the effect of core strength and effect of face thickness on deflection responses are determined.
In my opinion, the work is interesting and can be accepted after following revisions:
1- Please present some of main results in Abstract.
2- Please present novelties and research highlights of present study in the last paragraph of Introduction.
3- Please provide a brief review about the structure of paper at the end of Introduction.
4- The following Refs may be useful to be reviewed, since they are related
https://doi.org/10.1080/17455030.2022.2091182
DOI: 10.15632/jtam-pl.53.4.859
https://doi.org/10.1590/1679-78251099
5- Please proofread the paper regarding the punctuation, mistakes, …. For example, in Fig.1, Combined stress is true not combing.
6- Most of Eqs are general and well known; please cite them with Proper Refs.
7- The details of FEM model for validation in Figs 9 and 10 must be presented. Plasticity model, mesh convergency, numerical integration model, element type, …
8- The difference between difference solutions is too much, and it cannot be considered as a validation. Why have the authors proposed their solution as an efficient tool?
Please proofread the paper regarding the punctuation, mistakes and grammatical errors
Author Response
We are very grateful to your and the reviewers’ critical comments and thoughtful suggestions about our manuscript. The responses to reviewer's comment have been finished, please see the attachment.
Author Response File: Author Response.pdf
Reviewer 6 Report
The problem presented in the manuscript is very interesting. The behavior of layered structures subjected to dynamic loads is constantly the subject of interesting research. All the more so because these structures have common industrial applications.
Below I present some critical remarks in the order in which the relevant content appears in the manuscript.
1. Abstract. The abbreviation MFBS appeared without any explanation. It should be "Metal Foam Sandwich Beam (MFBS)".
2. Introduction - review of the literature.
Let me be clear - I consider it unethical to citee 30% of publications from one center (Wuhan). Without going into details, I would like to report the need to radically change the cited works, regardless of substantive issues.
3. Regardless of what works were cited, I found the literature review to be disjointed. I couldn't find any main idea or thought that would help readers understand the article. This part of the work requires significant improvement.
4. The English language is generally at a good level. I found some phrases that raise my doubts, e.g. on page 3:
"When suffering from external loadings, the structures will occur plastic deformation, 118 including plastic bending and axial tension."
5. Section 2. A Unified Yield Criterion for Sandwich Structures
I have great doubts about superposition. In the case of linear behavior, we can always talk about a superposition of effects (effects rather than forces). When the material behaves non-linearly, this is no longer the case. The question arises how to treat a perfectly elastic-plastic material (the authors do not define the constitutive relationship, so the author is forced to guess). Can the stress diagram be divided into two parts? Yes. The authors called them the M and N effect. Is it the bending and stretching effect? In my opinion - no. The moment and normal force can be obtained by integrating the normal stress distribution at height. Why the moment would not result in normal stresses in the core part - I have no idea. There are even more misunderstandings here, because the linear strain distributions drawn in Fig. 1 (there is a doubt whether they are really linear?) result in constant stresses on the fragments. I ask the authors to think carefully about this again. I had too little time and information to analyze it thoroughly. Nevertheless, the problem is interesting and intriguing, and your work intrigued me greatly.
6. Section 3. Analytical solutions.
The authors use the symbol "m" for mass, although it was previously used as M/Mp. What m means in equation 13 - I have no idea.
7. Section 4, equation (68). The notations used in the equation are not explained.
8. What does it mean "platform stress" - line 285?
9. The numerical model was not described sufficiently (I would not be able to make a similar model based on the description provided).
10. I don't see stiffness moduli in Table 1, but certain ones are needed.
The rest of the article presents parametric analyses, so they are a certain effect of the presented approach.
Author Response
We are very grateful to your and the reviewers’ critical comments and thoughtful suggestions about our manuscript. The responses to reviewer's comment have been finished, please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Accept.
Accept.
Reviewer 5 Report
The paper is revised accordingly and can be accepted in the present form.
Reviewer 6 Report
The authors introduced significant changes to the content of the article. In response to the review, he will also address several of the reviewer's comments. After the corrections, in my opinion the article is suitable for publication.
