A Fractal Prediction Model for the Friction Coefficient of Wet Clutch Friction Plates

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors,

please follow the comments:

1. the paper is not prepared according to the journal format. However, this is a matter of editing and easy to do, so it does not affect the substantive assessment of the paper.

2. Line 40 - please explain M-B fractal model.

3. After the first paragraph in the introduction, the authors should add a paragraph explaining the fractal theory. What is a fractal dimension, a fractal, and how these concepts can be used to describe rough surfaces. Please cite: https://doi.org/10.1016/j.jasrep.2024.104637

The authors correctly wrote that fractals are irregular and complex shapes, which, however, have important properties in the form of self-similarity to each other and scale invariance. Therefore, rough surfaces can be described by multifractals.

4. Lines 43-88 - The authors wrote what others have done on this topic, but they did not provide a reflective conclusion as to how good the earlier work was and how much it requires further development. Therefore, it is necessary to clearly indicate what the novelty of this work is.

5. Line 97 - research? please change the title of this section

6. The conclusions section is quite weak. Please write more conclusions from your research.

Author Response

1.The paper is not prepared according to the journal format. However, this is a matter of editing and easy to do, so it does not affect the substantive assessment of the paper.

Response 1:The format has been revised.

2.Line 40 - please explain M-B fractal model.

Response 2:The explanation of M-B fractal model has been added.Please see in P1:L37-42

3.After the first paragraph in the introduction, the authors should add a paragraph explaining the fractal theory. What is a fractal dimension, a fractal, and how these concepts can be used to describe rough surfaces. Please cite: https://doi.org/10.1016/j.jasrep.2024.104637

The authors correctly wrote that fractals are irregular and complex shapes, which, however, have important properties in the form of self-similarity to each other and scale invariance. Therefore, rough surfaces can be described by multifractals.

Response 3:The paragraph has been added after the first paragraph in the introduction.Please see in P2:48-54.

4.Lines 43-88 - The authors wrote what others have done on this topic, but they did not provide a reflective conclusion as to how good the earlier work was and how much it requires further development. Therefore, it is necessary to clearly indicate what the novelty of this work is.

Response 4:The novelty of this work has been added.Please see in P3:L124-128.

5.Line 97 - research? please change the title of this section

Response 5:The whole title is “Friction Plate Surface Roughness Contact Characteristics Research”. pPlease see in P3:L136.

6.The conclusions section is quite weak. Please write more conclusions from your research.

Response 6:The conclusions has been revised.Please see in L410-424.

 

 

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript "A Fractal Prediction Model for the Friction Coefficient of Wet Clutch Friction Plates", submitted for publication on Applied Sciences has been reviewed. In the abstract it is presented as theoretical modelling and experimental results of friction plates under various working conditions.

The manuscript is NOT well arranged. After a theoretical introduction the theoretical modelling is based on fractal prediction model for the friction coefficient. The experimental results have been carried out with MM6000 friction and wear machine. Results look more like a technical report rather than a research article. Materials and methods are not introduced (which materials have been tested, what about the surface roughness and so on).

The analysis of the state of the art is not up-to-date. All references are quite ancient. It is not clear what is new in relation to the state of the art. Images and graphs are low quality.

English is not a problem despite the authors are not english native speaker.

In conclusion I can't recommend the manuscript for publication in the present form and it must be rejected.

Author Response

1.The manuscript is NOT well arranged. After a theoretical introduction the theoretical modelling is based on fractal prediction model for the friction coefficient. The experimental results have been carried out with MM6000 friction and wear machine. Results look more like a technical report rather than a research article. Materials and methods are not introduced (which materials have been tested, what about the surface roughness and so on).

Response 1:The material and roughness values are shown in Table 1.Please see in P11:L360.

2.The analysis of the state of the art is not up-to-date. All references are quite ancient. It is not clear what is new in relation to the state of the art. Images and graphs are low quality.

Response 2:Some new literatures have been added and summarized.Please see in P1:L70-90,P3:124-128.

3．English is not a problem despite the authors are not english native speaker.In conclusion I can't recommend the manuscript for publication in the present form and it must be rejected.

Response 3:Syntax and format changes have been made.

 

Reviewer 3 Report

Comments and Suggestions for Authors

The authors present a method for predicting wet clutch engagement frictional behavior by analyzing rough surface characteristics using fractals. The concept is interesting; however, before the article can be considered for publication, the following major issues must be addressed:

1. The introduction needs significant revision to address three key aspects:

a. The authors reference a limited number of sources, many of which are not recent. To broaden the context of this work and to reference comparable studies, I have indicated some recent literature on wet clutch engagement behavior for the authors' consideration: https://doi.org/10.1016/j.ijmecsci.2023.108507, https://doi.org/10.1016/j.triboint.2021.106940,  https://doi.org/10.1016/j.triboint.2021.107125, https://doi.org/10.3390/pr8111474, 

b. The introduction should also be refined to better integrate and highlight the relevance of the cited references to the current work, rather than merely listing them.

c. Lastly, the introduction must explicitly state the novelties of the work.

2.  What is the main scope of using the fractal model?

3. The cited reference for Eq. 7 is a book which could not be located. The authors need to clarify and provide a proper explanation for this equation.

4. The derivation process of Eqs. 6, 11 is unclear. What is the physical explanation for D=1.5 condition? What does "the edge of the contact point" refer to (line 193) ?

5. What is the basis of the assumption in lines 180-182?

6. It is unclear if the surface topography characteristics obtained from the profilometer were used as inputs for the simulation. Furthermore, the detailed simulation procedure should be explained in the manuscript.

7. The authors should compare their analytical results directly with experimental data. Currently, the manuscript presents separate fittings for each of the two data sets.

Comments on the Quality of English Language

The English language used is satisfactory.

Author Response

1. The introduction needs significant revision to address three key aspects:

a.The authors reference a limited number of sources, many of which are not recent. To broaden the context of this work and to reference comparable studies, I have indicated some recent literature on wet clutch engagement behavior for the authors' consideration: https://doi.org/10.1016/j.ijmecsci.2023.108507, https://doi.org/10.1016/j.triboint.2021.106940, https://doi.org/10.1016/j.triboint.2021.107125, https://doi.org/10.3390/pr8111474,

Response a:The literature has been added.Please see in P1:L70-90.

b.The introduction should also be refined to better integrate and highlight the relevance of the cited references to the current work, rather than merely listing them.

Response b:The relevance of the cited references to the current work has been highlighted.Please see in P3:L124-128.

c.Lastly, the introduction must explicitly state the novelties of the work.

Response c:The novelty of this work has been added.Please see in P3:L124-128

2.What is the main scope of using the fractal model?

Response 2:Please see in P2:L52-54.

3.The cited reference for Eq. 7 is a book which could not be located. The authors need to clarify and provide a proper explanation for this equation.

Response 3:This book is a paper reference book, and pictures can be uploaded if necessary.

4.The derivation process of Eqs. 6, 11 is unclear. What is the physical explanation for D=1.5 condition? What does "the edge of the contact point" refer to (line 193) ?

Response 4:Eq 6: According to reference 7, the value range of fractal dimension is 1<D<2, so the median 1.5 is taken as the value of fractal dimension.

Eq 11:"The edge of the contact point" is revised as “the circumference of the circle of contact”

See in P6:L240.

5.What is the basis of the assumption in lines 180-182?

Response 5:The basis of the assumption has been added.See in P6:L224-228.

6.It is unclear if the surface topography characteristics obtained from the profilometer were used as inputs for the simulation. Furthermore, the detailed simulation procedure should be explained in the manuscript.

Response 6:The surface topography features obtained by the profiler are used as input for the simulation.

The simulation results are theoretical results based on the structural function measure dimension method.

 

7.The authors should compare their analytical results directly with experimental data. Currently, the manuscript presents separate fittings for each of the two data sets.

Response 7:The comparison results are shown in Figures 9(d) and 9(f).Please see in P13.

 

 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript has been significantly improved in the revised version and can now be accepted in the present form.

Author Response

Comments 1 The manuscript has been significantly improved in the revised version and can now be accepted in the present form.

Response 1  Thank you for your review

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have addressed some of the concerns raised by this Reviewer; however, further revisions are necessary to enhance the manuscript.

Specifically, the experimental data have not yet been directly compared with the simulation results, as they are presented in separate subplots. To better illustrate deviations, besides comparing the trends, these results should be plotted on the same graphs.

Additionally, the conclusions section should be presented as continuous text, rather than in a list form and it should also integrate key quantitative metrics.

Furthermore, the authors should clarify the conditions and inputs used to solve the equations presented in Figures 9d and 9f. Please specify the equations being solved and detail the necessary input parameters. How were these inputs approximated based on the experimental measurements so that experimental and simulation results can be compared?

Also the authors should clarify which surface roughness parameter Table 1 shows and also to fill in the thickness value in this Table.

Additionally, the authors have not resolved the issue with Ref 15. Please, consider cite additional references which can be found for this Eq.

Finally, the authors should elaborate on the methodology used to derive D and G from the profilometer measurements.

Author Response

Comments 1:Specifically, the experimental data have not yet been directly compared with the simulation results, as they are presented in separate subplots. To better illustrate deviations, besides comparing the trends, these results should be plotted on the same graphs.

Responses 1:The fitting data in Fig.9(d) and 9(f) are from experimental data. The experimental data have been directly compared with the simulation data in Figure 9 (d) and Figure 9 (f).

Comments 2:Additionally, the conclusions section should be presented as continuous text, rather than in a list form and it should also integrate key quantitative metrics.

Responses 2:The conclusion has been presented as a continuous text.Please see in P13:L429-444.

Comments 3:Furthermore, the authors should clarify the conditions and inputs used to solve the equations presented in Figures 9d and 9f. Please specify the equations being solved and detail the necessary input parameters. How were these inputs approximated based on the experimental measurements so that experimental and simulation results can be compared?

Responses 3:Related content has been added.Please see in P12:398-415.

Comments 4:Also the authors should clarify which surface roughness parameter Table 1 shows and also to fill in the thickness value in this Table.

Responses 4:The thickness has been added.Please see in P11:L360 Table 1.

Comments 5:Additionally, the authors have not resolved the issue with Ref 15. Please, consider cite additional references which can be found for this Eq.

Responses 5:The Ref 15 has been changed.Please see in P15:L488.

Comments 6:Finally, the authors should elaborate on the methodology used to derive D and G from the profilometer measurements.

Responses 6:D and G are calculated according to the formula provided in the Ref 25 and have been marked in the manuscript.Please see in P12:L381-382 and P15:L506.

Round 3

Reviewer 3 Report

Comments and Suggestions for Authors

Although the authors have addressed some of the comments, the manuscript is still not recommended for publication. The following issues need to be addressed:

1. The calculation of G and D should be explained in greater detail throughout the manuscript. Simply citing Ref. 25 is insufficient.

2. It is unclear why the authors chose to fit the experimental data and compare the analytical model with the fitted data instead of directly comparing it with the experimental data. A direct comparison between the analytical and experimental data is necessary.

3. The manuscript does not clearly explain the benefit of integrating the fractal model. The authors fail to discuss the results presented in Fig. 9 in sufficient detail. While the results in Fig. 9 seem promising regarding the model's predictive capabilities, it is unclear how the fractal model could be effectively used in the simulation of clutch systems if the evolution of the surface topography (required to calculate G and $D$) needs to be provided as input.

4. The authors should include a nomenclature section.

5. The Results section of the manuscript is underdeveloped. The results presented in Fig. 9 do not provide sufficient insight into how the fractal model, which is the main novelty of this work, affects engagement performance. The authors are strongly encouraged to include additional results, particularly focusing on the effect of the fractal parameters.

6. What is ψ in Eq. 2? How are Eqs. 6, 7 derived?

Author Response

Comments 1.The calculation of G and D should be explained in greater detail throughout the manuscript. Simply citing Ref. 25 is insufficient.

Response 1: The calculation of G and D has been added. Please see in P4:L183-L216.

Comments 2.It is unclear why the authors chose to fit the experimental data and compare the analytical model with the fitted data instead of directly comparing it with the experimental data. A direct comparison between the analytical and experimental data is necessary.

Response 2: The figures have been changed. Please see in P17, Fig 13(c)-(d).

Comments 3.The manuscript does not clearly explain the benefit of integrating the fractal model. The authors fail to discuss the results presented in Fig. 9 in sufficient detail. While the results in Fig. 9 seem promising regarding the model's predictive capabilities, it is unclear how the fractal model could be effectively used in the simulation of clutch systems if the evolution of the surface topography (required to calculate G and D) needs to be provided as input.

Response 3: The benefit of integrating the fractal model has been added. Please see in P8:L320-328.

Comments 4. The authors should include a nomenclature section.

Response 4: The nomenclature section has been added. Please see in P17-18:L578,Table of notes.

Comments 5.The Results section of the manuscript is underdeveloped. The results presented in Fig. 9 do not provide sufficient insight into how the fractal model, which is the main novelty of this work, affects engagement performance. The authors are strongly encouraged to include additional results, particularly focusing on the effect of the fractal parameters.

Response 5: The effect of the fractal parameters has been added. Please see in P11:L415-452,P17:L564-570,L572-577.

Comments 6.What is ψ in Eq. 2? How are Eqs. 6, 7 derived?

Response 6: ψ in Eq. 2 has been explained in P7:L281-282. The derivation process of Eqs.6, 7 has been added in P5:L217-298.