Creep Simulation and Validation for a Finite Element Analysis of Expanded Polystyrene-Based Cushioning Systems

Round 1

Reviewer 1 Report (Previous Reviewer 2)

Dear authors,

Thank you for the answers and explanations.

At this time, I consider that you have completed the manuscript taking into account some of my observations, and thank you.

 

However, in point 1 I recommended the improvement of the state of the art:

1.      The state-of-the-art is poorly written and does not report and discuss the most recent results related to the creep of Expanded Polystyrene. It should focus on the results achieved at the international level, by remarkable researchers, and published in journals. Based on an appropriate state-of-the-art, the author has to further emphasise the progress beyond the state-of-the-art, describing the novelty of the research and how the results will improve the scientific knowledge in the field of EPS creep behavior.

For example, Gnip, I. Y., Vaitkus, S., Keršulis, V., & Vėjelis, S. (2011). Analytical description of the creep of expanded polystyrene (EPS) under long-term compressive loading. Polymer Testing, 30(5), 493–500. doi:10.1016/j.polymertesting.2011.03.012

But there are other works with interesting results:

Gnip, I. Y., Vaitkus, S., Keršulis, V., & Vėjelis, S. (2010). Experiments for the long-term prediction of creep strain of expanded polystyrene under compressive stress. Polymer Testing, 29(6), 693–700. doi:10.1016/j.polymertesting.2010

etc

The state of the art should be improved. The results presented in other reference papers should be analyzed.

 The list of references has to be updated, by citing at least 10 recent scientific articles published in journals.

 

You summarized yourself by adding the 2 works indicated by me. I think that state of the art must be improved.

Regarding point 5:

5.  It is known that the coefficient of friction influences the simulation results (stresses and strains), but it is not specified in the paper.

it would have been interesting to present some results on the influence of the friction coefficient or a reference to other studies

 

Regarding point 7:

7. Simulation parameters are not specified. What are the plastic parameters of the material used?

the authors did not respond to the request

Regarding point 9:

9. The Burgers model constants determined with nonlinear regression are presented, but no analysis of the results is made (for example standard deviation), only the coefficient of determination is presented.

the authors did not respond to the request

=

 

Considering that the authors did not respond to all my observations, I cannot recommend publication at this time.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

I think that most suitable referees can review this paper, unfortnatly, I can not understand some things in the paper.

 

Regards

 

Referee

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report (New Reviewer)

This paper intends to validate the EPS creep behavior, for improving the FEA reliability with respect to EPS-based cushioning systems. The analysis is simple and not very originality. The language (English) in the paper should be improved.

 

1. In the sentence “To measure the horizontal displacement on the both sides of a test specimen, a jig was designed, in which…”, what’s the meaning of the “jig” ?

 

2. The typical creep behavior or microstructural evolution of the EPS should be provided using OM or SEM.

 

3. During the heating period (different-temperature tests), the density of the EPS could be changed in comparison to the as-received one. How does the authors deal with this problem?

 

4. The language in the paper should be improved.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report (Previous Reviewer 2)

Dear authors,

Thank you for the answers and explanations.

At this time, I consider that you have completed the manuscript taking into account some of my observations, and thank you.

Regarding the editing of the article: figure 10 has low quality, and the legend is not legible; all the bibliography must be written in English (see reference 15); reference 10 has the year of publication 2011, etc

 

In conclusion, I appreciate the work done and recommend the publication of the paper in Applied Sciences.

Reviewer 2 Report (New Reviewer)

The revised version can be accepted for publication.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

This paper only provides a very general description of the creep of EPS, and the experimental data is analyzed by statistics, which is of very limited significance for other researchers. Without any explanation and discussion of the mechanism, the models related to creep constructed have few meanings. As an academic paper,  the reviewer thinks it is far from enough.

Reviewer 2 Report

The purpose of this paper was to validate the EPS creep behavior, for improving the FEA reliability with respect to EPS-based cushioning systems. The elastic modulus and Poisson's ratio, as well as creep properties, were measured. Creep properties are validated to ensure the finite element analysis (FEA) reliability regarding the creep behavior of EPS-based cushioning systems.

The paper topic is interesting, the author has done a lot of work, but there are changes that must be brought to the paper, before being considered for publication, as follows:

1. The state-of-the-art is poorly written and does not report and discuss the most recent results related to the creep of Expanded Polystyrene. It should focus on the results achieved at the international level, by remarkable researchers, and published in journals. Based on an appropriate state-of-the-art, the author has to further emphasise the progress beyond the state-of-the-art, describing the novelty of the research and how the results will improve the scientific knowledge in the field of EPS creep behavior.

For example, Gnip, I. Y., Vaitkus, S., Keršulis, V., & Vėjelis, S. (2011). Analytical description of the creep of expanded polystyrene (EPS) under long-term compressive loading. Polymer Testing, 30(5), 493–500. doi:10.1016/j.polymertesting.2011.03.012

But there are other works with interesting results:

Gnip, I. Y., Vaitkus, S., Keršulis, V., & Vėjelis, S. (2010). Experiments for the long-term prediction of creep strain of expanded polystyrene under compressive stress. Polymer Testing, 29(6), 693–700. doi:10.1016/j.polymertesting.2010

etc

The state of the art should be improved. The results presented in other reference papers should be analyzed.

 The list of references has to be updated, by citing at least 10 recent scientific articles published in journals.

2. I don’t understand the novelty of this paper. From the reader’s point of view, it is necessary to write the novelty in the last paragraph of the introduction section.
3. For the uniaxial compression test, I don't understand what the loading rates are (page 3, line 122).
4. The preferred geometry of the specimen according to ISO 844 is the right prism with a base of 100mmx100mm and a thickness of 50 mm. Why have the recommended dimensions changed?
5. The mesh size of the model was large. How many elements did the model have? Maybe it was good to use progressive mesh.
6. It is known that the coefficient of friction influences the simulation results (stresses and strains), but is not specified in the paper.
7. Simulation parameters are not specified. What are the plastic parameters of the material used?
8. The technical content has to be improved. New arguments, based on the cause & effect discussion, have to be added to the results of the simulation, in order to scientifically explain the results of the analysis. It is interesting to present the stress distribution in the specimen after the simulation.
9. The Burgers model constants determined with nonlinear regression are presented, but no analysis of the results is made (for example standard deviation), only the coefficient of determination is presented.
10. It is not clear how the values presented in Table 5 were established. How was "conformity" calculated? 100%???

 

There are a number of minor grammatical and spelling errors. These can be easily edited.

For example, on page 10, line 277: table 5 not table 4.

While I am unable to recommend publication at this time, I believe that the authors should revise the manuscript and rectify its shortcomings.

Reviewer 3 Report

EPS is widely used in various industrial fields; in particular, when used as a packaging cushioning material, its greatest advantage is the ability to mass-produce uniform-quality cushioning materials. The authors explored a CAE prediction technology development of inclinations for unitized loads of packaged appliances applied to EPS-based cushioning systems. In the article, the EPS creep properties were validated for ensuring the reliability of the FEA results for the creep behavior of EPS-based cushioning systems. But the paper need further improvement:

 

1. There are too many keywords and the initials of keywords should be capitalized.
2. In the first and second paragraphs, the introduction of EPS materials is too much, and it is suggested to be appropriately deleted.
3. Why are the mechanical properties of materials measured only at temperatures ranging from 0 to 60 °C? Beyond this range, will the mechanical properties be significantly affected by temperature?
4. It can be seen from Table 5 that with the increase of density, the value of “Conformity” gradually decreases. Whether the accuracy of the prediction method can be considered to decrease with the increase of density? Please give a reasonable explanation.
5. In the conclusion, the author refers to “With increasing density, the EPS Poisson's ratio increases almost linearly”, but the article only studies the specific density range, this conclusion seems not very rigorous.
6. The coordinate axes of some pictures are not marked, please check.
7. There are few references in this paper, and most of them are not in recent years. It is suggested to supplement and replace them.