Study on Performance and Structural Design of Bamboo Helmet

Round 1

Reviewer 1 Report

The manuscript on performance and structural design of of bamboo helmet contains interesting data. The processing is well described but the presentation of data is often unclear e.g. figs 3 and 4.

By the side of the problem of readability, the information is not transmitted. A remodelling of the section 3: Results and discussion. I note also a confusion between bamboo and its components e. g.  line 272—273 the crystallinity of bamboo must be the crystallinity of cellulose.

The conclusion is also too vague.

Author Response

Reply one comment to reviewer

Point 1: The manuscript of bamboo helmet performance and structural design contains interesting data. The process is well described, but the presentation of the data is often unclear, as in Figures 3 and 4.

Response 1: Based on this comment, we rearranged and painted the picture to make it clear and easy to read.

Point 2: In terms of readability issues, information does not transfer. Refactoring in Section 3: Results and discussion. I also note the confusion between bamboo and its components, as in lines 272-273 the crystallinity of bamboo must be that of cellulose.

Response 2: Based on the reviewer's comments, the impact performance and color changes of the helmet were reshaped in section 3 to ensure clear structure. In terms of the expression of crystallinity, the crystallinity of bamboo becomes that of bamboo cellulose.

Point 3: B The conclusion is too vague.

Response 3: Based on the comments of reviewers, we added specific shock resistance times and color changes to our conclusions. At the same time, the product performance and mechanism are divided into two parts.

In this study, the material optimization, weaving and manufacturing of bamboo helmet were realized by making full use of the gradient structure and flexibility of bamboo. The biodegradable bamboo helmet developed in this work has excellent environmental adaptability, and the impact strength of high temperature, low temperature and soaking water is 2.85kN, 2.92kN and 2.59kN respectively, which is lower than 4.9kN. After modification with urea-formaldehyde resin, the color Labs of bamboo safety helmet changed from 58.13, 2.87, 45.39 to 63.92, 5.04, 20.93, and glossiness increased from 0.96 to 1.17. The photosensitivity and gloss of the surface of bamboo helmet modified by urea-formaldehyde resin were improved and the warning function of bamboo helmet was enhanced.

The excellent performance of bamboo helmet comes from the structural design that imitates the gradual change of bamboo and the modification of urea-formaldehyde resin. As a structural optimization, the bamboo helmet adopts the high strength bamboo green part as the top skeleton, the second strength bamboo part in the hat, and finally chooses the low strength bamboo yellow part. The middle of the helmet. The impact resistance of bamboo helmet modified by urea-formaldehyde resin was increased from 4.17kN to 1.17kN. Urea - formaldehyde resin modified to fill bamboo pores and repair bamboo defects. At the same time, urea - formaldehyde resin and bamboo surface chemical reaction, forming a tight bond. In addition, the crystallinity of modified bamboo decreased from 36.72% to 34.09%, which improved the impact resistance of bamboo to helmet. The development and manufacture of bamboo helmet provide a supplement and choice for the traditional safety helmet market, and open up a new way to use bamboo efficiently and with high quality.

Author Response File: Author Response.docx

Reviewer 2 Report

Hi, This is a good topic, however, further details are required.

1) The research methodology is presented very vaguely. 

2) You need to discuss how to create contact between the different members.

3) The type of element in meshing was ignored.

Overall, the conclusion does not reflect the main contribution of the paper. 

Author Response

Point 1: The research methodology is presented very vaguely.

Response 1: According to the opinions of the reviewers, we rewrote the research methods in the manuscript. The rewritten research methods include bamboo safety helmet manufacturing, bamboo safety helmet performance test and anti-impact performance mechanism.

Point 2: You need to discuss how to create contact between the different members.

Response 2: In this study, firstly, the properties of bamboo helmet were discussed, including the environmental adaptability of bamboo safety helmet at high temperature, low temperature and soaking in water. At the same time, the color characteristics of safety helmet were studied, which showed that the color sensitivity of safety helmet was increased after urea-formaldehyde modification. After that, the performance enhancement mechanism of bamboo helmet was discussed, including the structural design optimization of bamboo helmet and the physical and chemical strengthening mechanism of urea-formaldehyde resin on bamboo. By discussing the performance of safety helmet and the reasons for its excellent performance, the characteristics of bamboo safety helmet were studied.

Point 3: The type of element in meshing was ignored.

Response 3: By examining the data, we determine that the type of mesh in the finite element analysis is the triangular mesh of free mesh.

Author Response File: Author Response.docx

Reviewer 3 Report

Manuscript No.: forests-1781687-peer-review

Title: Study on performance and structural design of bamboo helmet

Authors: Chen et. al.

 General

The article describes the possibility of making a protective helmet from bamboo, which is then impregnated with urea-formaldehyde resin. In general, the topic is interesting and could be potentially useful, but the results in the article are difficult to use because many methods described are quite unclear. The results are also presented in a rather confusing manner and contradict each other in some places.

The authors explain that helmets made of bamboo are environmentally friendly. Explain the environmental impact of urea-formaldehyde resins!

Specific

 All Figures: the text is not clear. Font is to small.

L58-69 The aim of the article is not clear. The last paragraph in the introduction is basically the abstract and not the aim.

Figure 2: The individual production steps are not clearly shown. In individual pictures, only some machines can be seen, which could show anything.

L94-95 “The test was performed using a drop hammer at the height of 1000 mm, and the shock absorption force was recorded (Fig 3).” – On the figure 3 only the results are presented and not the method as indicated by the sentence. Why the Figure from the results is cited in the method section?

L117-124 Where did you get the information about the material? Why is the helmet material modelled as an isotropic material? How is the bamboo fiber modelled? What are the other parameters? Why is the support fixed when the real conditions are not?

Figure 5a and 3b. Why the impact absorption force is different in the figures under the same condition : Figure 3b, untreated 1.68 kN  and Figure 5a: untreated 4kN??

L302 “…and its impact strength is lower than 4.9 KN.” How the strength can be explained with kN? The appropriate units can only be MPa or similar. Are you talking about the impact transmission force?

L310 “impact resistance of the bamboo helmet increased from 4.17 KN to 1.17 KN” The values are decreasing and not increasing. Express the results more clearly!!

Author Response

Response to Reviewer 3 Comments

Point 1: All Figures: the text is not clear. Font is to small.

Response 1: According to the reviewer's opinion, we have modified the picture to make it easier to read.

Point 2: L58-69 The aim of the article is not clear. The last paragraph in the introduction is basically the abstract and not the aim

Response 2: According to the opinions of the reviewers, we have modified the relevant sentences as follows:' In this study, the helmet's performance was evaluated by impact strength and modified color change. Then, the mechanism of helmet performance enhancement is studied. The structural design characteristics of bamboo safety helmets are studied by finite element analysis. The mechanism of physical and chemical enhancement of helmet by urea-formaldehyde resin was studied by SEM, FTIR, and XRD. The research results provide a theoretical basis for the development and function expansion of bamboo helmets and provide a new way for global energy saving and emission reduction and replacing plastic with bamboo.’

Point 3: Figure 2: The individual production steps are not clearly shown. In individual pictures, only some machines can be seen, which could show anything.

Response 3: We are very sorry for this problem, due to the low degree of automation of helmet production, mainly by manual production, so the picture uses some machines as the representative.

Point 4: L94-95 “The test was performed using a drop hammer at the height of 1000 mm, and the shock absorption force was recorded (Fig 3).” – On the figure 3 only the results are presented and not the method as indicated by the sentence. Why the Figure from the results is cited in the method section?

Response 4: We are very sorry for this error, which is caused by the mislabeling of the picture. Figure 3 shows the test results rather than the test method, and there is no picture of the test method in the manuscript. We have revised the manuscript.

Point 5: Figure 5: L117-124 Where did you get the information about the material? Why is the helmet material modelled as an isotropic material? How is the bamboo fiber modelled? What are the other parameters? Why is the support fixed when the real conditions are not?

Response 5: We are very sorry for the trouble caused by this problem to the reviewers. The material information in our manuscript comes from The structure and mechanics of Moso bamboo material. The reason for the isotropy of helmet modeling is that the simplified model can simulate the performance changes of safety helmets during impact, which is not only for bamboo helmets but also for plastic helmets, so in the finite element analysis, the fiber model is also simplified to provide more concise results. In addition, the fixed support at the bottom is set in the simulation because, in the actual use of the safety helmet, it needs to be carried out with the plastic head cover, and the force supporting part is the bottom plastic head cover.

Point 6: Figure 2: Figure 5a and 3b. Why the impact absorption force is different in the figures under the same condition : Figure 3b, untreated 1.68 kN  and Figure 5a: untreated 4kN??

Response 6: The reason for this is that we have used two different batches of samples in different tests, so we have different results. At the same time, the results of the two experiments are similar.

Point 7: Figure 2: L302 “…and its impact strength is lower than 4.9 KN.” How the strength can be explained with kN? The appropriate units can only be MPa or similar. Are you talking about the impact transmission force?

Response 7: Our impact mechanics test is based on the reference standard GB 2812 2006, so the unit is KN, and the safety helmet cannot be measured by MPa because of the difference in force size and material. KN is used to express the possible weight of the head, which can show the performance of the helmet.

Point 8: Figure 2: L310 “impact resistance of the bamboo helmet increased from 4.17 KN to 1.17 KN” The values are decreasing and not increasing. Express the results more clearly!!

Response 8: We are very sorry to cause trouble to the reviewers, because the lower impact resistance represents a better safety strength, so when the impact strength value decreases, its strength is increased. In order to eliminate this problem, we changed the expressions such as' increase'or 'decrease' described in the manuscript to 'change'.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The revised version is satisfactiry.

Author Response

Thank you so much for your valuable comments.

Reviewer 2 Report

 The revised version was considered. The suggested modifications were completely addressed.

Author Response

Thank you so much for your valuable comments.

Author Response File: Author Response.docx

Reviewer 3 Report

The authors have considered some comments, but not all.

For example, the comment:

All Figures: the text is not clear. Font is too small.

This comment is not considered at all. On figure 4a also at big magnification of pdf file the name of axes are not clear!!!!!!

And further:

Figure 5a and 3b. Why the impact absorption force is different in the figures under the same condition : Figure 3b, untreated 1.68 kN  and Figure 5a: untreated 4kN??

And authors response:

Response 6: The reason for this is that we have used two different batches of samples in different tests, so we have different results. At the same time, the results of the two experiments are similar.

 How similar are the results of two tests if the first test gives a value of 1.68kN and the second test gives a value of 4kN. Plot the results together as an average or draw two sets of results. Also explain in the text whether it is one mean or two different sets of results!!!!

With the current presentation of the results, the reader is completely confused because first the results represent one value and later another value for the same condition.

Author Response

Response 1: I am very sorry to confuse the reviewers. We attach great importance to the opinions of the reviewers, and we modify the font in the picture to make it easier to read according to the reviewers' opinions.

Response 2: I am very sorry to confuse the reviewers. In Fig 3, the untreated means that the untreated impact resistance is 1.68KN without high temperature, low temperature or immersion treatment, while the untreated one in Fig 5 is not treated with UF and the untreated impact resistance is 1.68KN. So the two unprocessed represent different ways of handling. In order to avoid confusion, we change the untreated in Fig 3a to control. The specific modifications are as follows：

‘Compared to the control bamboo helmet at room temperature, the impact force increased after high temperature, low-temperature, and water immersion treatments (Fig 3b).’

We are very sorry for the trouble my answer has caused to the reviewers, and we would like to express our deep apologies here.

Author Response File: Author Response.docx

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.