The Effect of Impactor Geometry on the Damage Patterns Generated by Low-Velocity Impacts on Composite Pressure Vessels
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsMany thanks to the authors for this really interesting and useful research on a not simple topic. Very interesting the results about the influence of the shape and the diameter of the impactors.
I suggest the publication after some revisions necessary to help the reader in the understanding.
Line 23: …..then analyses the shape and size of the impactors influence damage patterns, …………… I would add: “and the curved shape of the vessel”;
Line 107: ………….. and resulting damage “on a curved shape”;
Line 118: please, write the value of the temperature;
Line 157 and figure 2a : the shape of the impactor seems to be conical. Please, enlarge the particular of figure 2a; How many tests per each conditions?
Page 5, line 163 – 164: why did you select these energy levels? The impact point was the same in all the tests?
Page 8: You foicused only on the damage evolution but it would be interesting to add the load curves of the different test conditions overlapped;
It would be good to plot the data from Table 3 on a graph;
How did you investigate the dewlamination? And how did you see that the delamination propagated only between layers oriented at 90° and others? It seems to be a qualitative investigation.
Figure 6 needs explanation: what is the difference with the tests showed in figure 5? It seems that the numerical model doesn’t see the damage. On the contrary, a more clear correlation is necessary. The same for figure 7. In the latter, is the cut section longitudinal or transversal?
Line 363 – 368: I would expect the contrary;
What is shown in figure 8 and 9? The numerical simulations? However, they show qualitative results. I would suggest to plot the measurements to give an idea of the trend of damage propagation.
Also figure 10 is not clear and it is not clear the difference with figure 9 and 8 about matrix cracks and fibre failure. It is always underlined the increasing of the damage at the increasing of the impact energy. But this results is common and expected. There is nothing new in this aspect.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe present manuscript presents an experimental and computational modeling investigation of low-velocity impact (LVI) on Type IV carbon fiber composite hydrogen pressure vessels. The study aims to validate the accuracy of a hybrid computational model on damage prediction by comparing its results with those obtained experimentally. The primary variables examined include impactor geometry (spherical and cylindrical) and impact energy levels (300 J, 400 J, and 500 J). Despite some minor writing issues, the manuscript is well-organized, and the study is clearly described. However, the document lacks of a deeper discussion on damage mechanisms observed and how they are related to the experimental and computational data. From may point of view, the manuscript can be considered for further publication following major revisions especially those concerning results discussion. The attached document contains recommendations and comments that may improve document quality before publication.
Comments for author File: Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe paper presents an interesting topic and the fabrication of the pressure vessel is an interesting study case example. The attached file gives suggestions and observations for the improvement of the paper. The most important are listed bellow:
a) in general, leave a space between number and units of measurement and write units with normal characters and not italic;
b) page 2 line 56 - be specific and divide citations into categories of subjects as specific comments are done subsequently;
c) cite references in order; citation [13]; where is reference [12] cited? after [13] should come in order citations [14], [15], [16]; after [18] cite references [19] and [20];
d) page 3 line 119 - give details about the temperatures utilized during the curing process;
e) give reference for material properties used in Table 1;
f) page 6 line 177 - give details about the used elements and their number in each layer;
g) page 6 lines 192 and 193 - this statement is not clear - please explain in detail;
h) page 7 line 229 - give values of the material constants used in the numerical model;
i) Figure 4 - explain what is the meaning of the legend for numerical simulation leave space before J;
j) Table 3 - which delamination? was only one or several? where is this delamination?; why "indentation" written here and not in the same row as surface damage and delamination?
k) Figure 5 - put the scale in between(a) and (b) and not bellow figures as to be seen more clearly; everywhere space before J;
l) Figure 6 - leave everywhere space before units why are figures (a) needed as you have to point out more clearly the delamination; in figures (b) the quality of the pictures is quite bad, as being out of focus; can you improve them?
m) Figure 7 - why is now the pressure vessel wall flat and not curved as in Fig. 6;
n) page 13 line 360 - make specific comments concerning the differences in the delaminations; where are they situated?
o) page 13 lines 365-368 - these are no news as the impact with a spherical impactor in very localized!
p) Figure 9 - what is the meaning of the legend? between 400 J and 500 J there is no big difference in the damage - why?
q) page 17 - place Figure 10 bellow this paragraph and not on the next page;
r) page 19 line 465 - not really!
Comments for author File: Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThe paper presents a well-structured and comprehensive investigation into the effects of impactor geometry on damage patterns in composite pressure vessels subjected to low-velocity impacts. The combination of experimental and numerical approaches strengthens the reliability of the findings, and the validation of the numerical model against experimental results adds credibility to the research. Please find my comments below to improve this manuscript before publications:
1) Some figures (e.g. 2 and 3) lack sufficient labeling or captions to make them fully self-explanatory.
2) More relevant studies should be provided in the literature review as there are currently only 5 refs but I am confident there are more (relevant ones) in the literature.
3) Inconsistency in table/figure numbering ([1] or 1).
4) Line 180 - 181, the authors need to provide solid support to why the region can be ignored to save computational cost. This problem space reduction approach must be justified. I recommend a read and reference this study to support this argument (https://doi.org/10.3390/ma16247580).
5) The practical implications of the findings could also be elaborated further. While the study provides valuable insights into damage mechanisms, it would benefit from a more detailed discussion on how these findings can influence real-world applications, such as safety standards or design recommendations for composite pressure vessels. Additionally, the paper could include more specific suggestions for future research, such as exploring additional impactor geometries or testing under operational conditions.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsAll the comments were addressed, although the manuscript formation must be revised (sections' numeration and other minor text typos and grammar details). After those minor revisions, the manuscript is read for publication.
Reviewer 3 Report
Comments and Suggestions for AuthorsI still do not understand why in many places you do not want to leave a space between number and units of measurement, as before mm and J.
Reviewer 4 Report
Comments and Suggestions for AuthorsThe authors have revised the manuscript well, and provided a robust respond and rebuttal to reviewer. I can now recommend paper acceptance.
