Strength and Deformation Analyses of Selected Filaments for Large-Format Additive Manufacturing Applicable to the Production of Firefighting Water Tanks

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript entitled “Stress and Deformation Analysis of Materials for the Large-Format Additive Manufacturing of Firefighting Water Tank” by Hnilicová et al. investigates the feasibility of using a library of high-performance polymers to manufacture firefighting water tank through LFAM technique. The authors highlight the design considerations that dictate the final strength and deformation of the printed part. The results presented suggest that the polymers can perform adequately for the application although their performance is still inferior to steel and composite materials. The work performed is missing a few critical aspects regarding the fundamental analysis of the material properties and process physics. There are some major issues associated with the manuscript, as outlined below, that makes it unsuitbale for publication in the Applied Sciences journal.

Comments to the Authors:

1.       A major criticism is that much of the manuscript simply states what has been found from the simulation rather than synthesizing the results to provide clear insights into the underlying physics/chemistry that govern the observations. Much of the manuscript reads as a paragraph-by-paragraph listing of the results trying to characterize the mechanical and bioactivity characteristics of the prepared composites but with the absence of a narrative tying them together. It is much more of a listing and much less of critical thoughts on the work that it reports on. There are few real insights, and many of the needs for moving forward are missing. The manuscript would benefit from a clearer description of exactly what the critical challenges are, what routes have been demonstrated to somewhat address these (as well as the failures, which are valuable to know so future researchers do not go down the same proverbial rabbit hole) as this would better set up the future direction.

2.       The entire Results section is condensed into 2.5-3 pages of discussion which is not sufficient at all. No effort has been made to characterize the different materials and correlate that with their printability and eventually stress/deformation behavior.

3.       The bullet points in the Introduction are well known in the AM community and might be repetitive.  The introduction is missing a brief paragraph highlighting what is fundamentally new in this current work.

4.       Please either use “big area additive manufacturing” or “large format additive manufacturing” in the manuscript. Also, please declare them to be BAAM or LfAM at the first mention in the manuscript and continue using the abbreviation for the rest of the manuscript.

5.       The Conclusion section reads like an Introduction section. Please be more specific and quantitative about how this work is advancing the current state of the art and focus less on the existing challenges in the field.

6.       Resolution of Figure 2b must be improved.

7.       A lot of general information is provided in Section 2. Readers can easily find this information on the website of each of the materials; they do not add anything significant to the current manuscript.

8.       No mention of simulation or modeling was made before Section 3 and as such it seems to come up suddenly.

 

 

Comments on the Quality of English Language

Please carefully go through the entire manuscript and address any spelling and/or grammatical mistakes.

Author Response

The answer is attached in the file

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The paper, through its title, arouses the reader's interest. However, the content of thepaper does not correspond to the title.

The introductory part of the paper insists on presenting the specific aspects of manufacturing through additive technologies: LFAM and BAAM.

The content of the paper, however, presents the results of finite element analysis applied to a water tank. The only connection with the topic of the paper and with the introductory part is represented by the materials under analysis.

I believe that the hypothesis according to which the authors consider homogeneous materials is not correct. The various structures that can be obtained through additive technologies must be taken into account.

I think the authors should limit themselves to one or two materials and insist on the technological factors of the 3D printing process and their implications on the obtained structures. Finite element analysis is interesting to perform on various types of structures.

In this sense, I recommend either changing the title and the introductory part of the article or performing analyzes on the real structures.

Moreover, the development of a test program to determine the mechanical characteristics of the real structures would provide the certainty of the efficiency of the application of additive technologies for the analyzed product.

Author Response

The answer is attached in the file

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The authors introduced LFAM method with multiple 3D printable materials, along with composite materials on manufacturing firefighting water tanks. FEA was done on the water tank with different materials. The max stresses, along with deformation were extracted and visualized for further validation tests. The writing and organization of the paper is relatively clean and clear. However, the following points should be addressed and clarified before reconsideration.

1.        Is the static hydrostatic pressure representative enough for the water tank? Since it is attached to the vehicle and some acceleration and velocity should be added too. Please provide some justification on this.

2.        Please provide the documentation or references of the material properties shown in table 1.

3.        Please clarify how the two categories of material are applied in ANSYS model. What kind of rule of mixture is applied here? This may also explain another question: how could the authors show the stress and deformation on two materials (resin and mat M5) separately in the simulations, shown in Fig. 5?

4.        What’s the goal here to show the max stress on resin and M5 separately, since they are mixed as composite materials?

5.        Does Von Mises suitable for all the 3D printable materials? Usually, Von Mises is used for ductile materials, like metal. Can the authors provide justification on why the 3D printable materials use Von Mises stress as threshold here? At least ABS behaves more closer to brittle materials, instead of ductile materials. Also, Von Mises is based on J2-plascity, which means it can’t detect hydrostatic stress components in the stress tensor, which is the loading condition that the authors added on the water tank. The max. principal stress should be more robust here for the 3D printable materials. 

6.        Legend shown in Fig 5 is Von Mises, but in the context, it says max Principal. Please correct.

7.        Please explain why the authors use middle-section integration points to visualize the results, instead of the surface ones, since they are larger.

8.        Provide a plot with the ratio of strength/mass for different materials is more efficient to show the benefits of the 3D printable materials.

Thanks!

Author Response

see attachment

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

1. What do the authors mean by "advanced fiber"? This should be explained.
2. The introduction can be better organized for coherence, especially regarding the idea of using composite materials instead of homogeneous ones.
3. The authors used two terms, "production volume" and "production speed," for the same value in lines 78-79.
4. When discussing composite materials, it's important to note that mixing two polymers to create composite materials is a chemical process resulting in a new compound. In contrast, adding fibers to a material without full integration is a physical mixing.
5. The authors did not explain the abbreviation DATEFF.
6. The authors stated that composite materials and steel are three-dimensional materials without explaining why.
7. "LFMA" should be corrected to "LFAM."
8. It is unclear why the authors discussed the importance of adding fibers to the filament when the research focuses on comparing composite materials and common materials in 3D printing for producing fire-fighting tanks.
9. The authors mentioned the necessity of conducting an analysis using Ansys for the filament, but the analysis was done for the tank instead.
10. At the beginning of the experiments section, it was not mentioned that there would be a comparison, through Ansys analysis, between tanks manufactured with composite materials and different 3D printing materials.
11. It should be clarified if the study aims to examine the total effect. What is the benefit of studying the stresses separately between the inside and the outside? There is no explanation through pictures about whether compressive forces were applied, their center of influence, or their direction.
12. In Figure 3, it is unclear why the maximum deformation value is greater than the highest value indicated by the color scale. For example, in ABS, the maximum value is 19, but the red scale's maximum value is 12. Why?
13. The abstract suggests the study is about using fibers inside the filament in 3D printing, but the research goes in a completely different direction.
14. The purpose of analyzing each individual layer of the composite materials in Figure 5 needs to be explained more clearly. It should be clarified whether the tank was considered as made of each layer separately with forces applied to it or if the test was done by adding layers incrementally. If the aim was to study the deformation of the composite material as a whole, what is the benefit of studying each layer alone?
15. During the explanation of the results, the authors mentioned that the stress values do not exceed the tensile properties of the material listed in Table 2. However, Table 2 does not contain these values.
16. An important observation from the results is that when the difference between internal and external stresses increases, the total deformation elevates. This should be highlighted.
17. The authors did not mention that computer modeling would be conducted in this research or provide any information about the possibility of actual 3D printing in the future. The technology used in 3D printing can impact the results.
18. The authors discussed the use of fibers in materials for printing but did not clarify how this relates to his research.
19. In Chart No. 8, the authors compared the yield strength point and tensile strength with the simulation results, which is good. However, it would be better to apply this comparison to all materials within the same figure, not just steel.
20. The authors did not include a paragraph for recommendations, proposals, or a future vision.

Comments on the Quality of English Language

N/A

Author Response

see attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have addressed the comments raised by the reviewers in their revised submission. However, a discussion pertaining to the rationale behind selecting the materials for LFAM should be provided in the Introduction section. Consider the following publications to construct that discussions.

1. https://doi.org/10.1016/j.progpolymsci.2021.101411

2. https://doi.org/10.1016/j.addma.2020.101218

3. https://doi.org/10.1016/j.addma.2021.102177

Author Response

the answer is attached

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

My comments, after reading the authors' response, are the following:

- The title, even in this version, does not reflect the content. I believe that the work must address:

- either a simple finite element analysis of the reservoir structure - in this case it does not bring anything new

- either to focus on the manufacturing of the structure through additive technologies - this requires other studies which, from the authors' answer, it is understood that they are not possible to carry out

- At point 3, the authors consider it correct to study a homogeneous structure. If no details are provided regarding the printing technology, there are no arguments in this regard.

- Point 6 - without having the possibility to perform the practical experiment - printing and, respectively, tests on different printing technologies - we cannot risk giving credibility to an ordinary FEM analysis.

Author Response

the answer is attached

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

All comments and questions have been addressed.

Reviewer 4 Report

Comments and Suggestions for Authors

N/A