Fatigue Reliability Prediction Method of Large Aviation Planetary System Based on Hierarchical Finite Element
Round 1
Reviewer 1 Report
Good work and well written
Conclusions may be shortened
Author Response
Dear reviewer, we are grateful for your effort in reviewing our paper and your positive feedback. We have carefully addressed all the reviewer’s concerns.
We have made appropriate adjustments and deletions to the concluding section of the manuscript。
We hope you are satisfied with the answers we provided.
Reviewer 2 Report
Comments and Suggestions for Authors
The paper reports an interesting and very useful experimental work covering behavior of the large aviation planetary system. The manuscript is well structured and can be published after some revisions. The reviewer enjoyed reading this paper.
The manuscript has some weaknesses. Mentioned below aspects should be taken into consideration during the revision:
1. Units and abbreviations:
I suggest adding "Nomenclature" (as list of symbols, list of abbreviations and subscripts and others) in the manuscript.
2. Introduction:
Literature analysis should be expanded. It is recommended to better justify fatigue test apparatus, especially for bending and gear bending fatigue test. See for example the fallowing papers:
- https://www.mdpi.com/2075-4701/11/11/1871 - about crack propagation in single tooth bending fatigue;
- https://doi.org/10.1016/j.mechmat.2020.103410 - fatigue bending with controlled damage degree;
- https://doi.org/10.1515/meceng-2015-0006 - bending-torsion fatigue test stand allows to set the pseudo-random history of energy parameter.
3. Experimental program:
a. Do the authors have SEM fractographies for the tested elements? This could help to better understand the failure mechanisms.
b. Surface metrology - do you have information about the surface roughness of tested tooth?
4. Conclusions:
a. This section is very well detailed and explained. The most important conclusions are addressed. Please, can you change the title of this section to "Concluding Remarks"?
b. The practical usefulness of the results should be emphasized.
c. The main limitations of the present method must be identified and discussed in the end of this section.
Author Response
Dear reviewer, we are grateful for your effort in reviewing our paper and your positive feedback. We have carefully addressed all the reviewer’s concerns. Please see below our replies. We hope you are satisfied with our answers and the new data we provided. Changes highlighted in yellow have been made accordingly, in the revised manuscript and in the vised supplementary information.
Author Response File: 
Author Response.pdf
Reviewer 3 Report
The paper deals with fatigue assessment of a large aviation planetary system. Finite element analysis has been performed on the whole planetary system while a sub-model is adopted to assess the stress at the root of the teeth.
The paper is well written with a clear explanation of the problem statement and literature review. The results are presented in a clear way. References are up to date and the English language is fine.
However, one of the main issues that this reviewer encounter in this work is related to the capacity of the proposed procedure to shorten the modelling time. As reported in the paper, large FE analysis is required to assess the overall stress in the planetary system. Mechanical components have been modelled with very fine mesh (for example Table 3, where the number of elements/nodes has not been reported). In addition, the hierarchical FE analysis aim is to obtain the elastic deformation of the system that can influence the meshing between gears, increasing the tooth root stress. It has been shown, in Figure 9, that the maximum stress in the tooth root, taking into account the system deformation, is equal to 270 MPa vs. the undeformed system deformation which is 308 MPa. Compared to ISO 6336 calculation (305 MPa) and the undeformed system configuration (308 MPa), the assessed value taking into account the system deformation is not conservative. This reviewer thinks that the Authors should pay more attention in highlighting the computational effort to do a hierarchical FE analysis compared to the reliability of the results and to the easy results prescribed by the standard.
Other minor points to be considered before publication are the following:
1. Table 3: reports the number of nodes/elements for each modelled device. I would also recommend adding the RAM amount needed to perform the simulation
2. Figure 3: Do not put the text over the images.
3. Figure 7: Where were taken the data for the surface modification? They should be
4. Figure 14: Where historical data were taken? They are too low data. Much experimental data must need.
For all the previous reasons, the reviewer recommends major amendments of paper for publication in Metals.
Author Response
Dear reviewer, we are grateful for your effort in reviewing our paper and your positive feedback. We have carefully addressed all the reviewer’s concerns. Please see below our replies. We hope you are satisfied with our answers and the new data we provided. Changes highlighted in yellow have been made accordingly, in the revised manuscript and in the vised supplementary information.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Dear Authors,
thank you for your effort in reviewing the paper. The main issues of the first revision have been clarified.
I would ask you if you can rearrange the introduction to be more clearer and include the observation of Point 1 and Point 2 in the manuscript. This would help the reader to really understand the value of your work.
After that, the paper can be accepted for publication in Metals.
Author Response
Dear reviewer, we are grateful for your effort in reviewing our paper and your positive feedback. We have carefully addressed all the reviewer’s concerns. Please see below our replies. We hope you are satisfied with our answers and the new data we provided. Changes highlighted in yellow have been made accordingly, in the revised manuscript and in the vised supplementary information.
We have made deletions and changes to the introductory section.
We added the relevant content about point1 and point2 in the manuscript. They are respectively in 2.2.2—2.2.4, line 207-210, and line 476-483.
