Dynamic Characteristics Analysis of a Rod Fastening Rotor System Considering Contact Roughness
Round 1
Reviewer 1 Report
This paper deals with an interesting topic from a tribological point of view. However, many aspects make that the paper needs to be completely reworked. In fact, since Buschan's work in 1990, it is very classical in contact mechanics to use the Weierstrass function coupled to contact mechanics to incorporate fractal structures of rough surfaces.
The main criticisms are the following.
- Nowadays, simulations use the 3D Weierstrass function in contact mechanics. Justify the 2D and the limitations.
- There are no experimental validations. Add it.
- Part 3.1 should be revised, there are no references for equations eq.4 to eq.18, nor justifications for the material and mechanical assumptions.
- In part 3.2, reference 32 and 33 are quoted. However, the origin is in Majumdar, A., & Bhushan, B. (1991). Fractal Model of Elastic-Plastic Contact Between Rough Surfaces. Journal of Tribology, 113(1), 1. doi:10.1115/1.2920588. And in 32 and 33, it is not this formula because an additional term is introduced: a domain extension factor.
- I don't understand eq.21. nmax , is not precise? If I understand correctly, you sum all the real contact area for the nth level asperity surfaces? but many asperities for each nth surface are not in contact.
- Why limited to delta=1.34 ?
Author Response
Thanks for reviewers’ comments concerning our manuscript entitled ‘Dynamic characteristics analysis of a rod fastening rotor system considering contact roughness’. Those comments are all valuable and helpful for revising and improving our paper. Also, reviewers’ questions get us to think seriously about things we have never thought about before.
- Nowadays, simulations use the 3D Weierstrass function in contact mechanics. Justify the 2D and the limitations.
Response: According to the existing research, the 2D Weierstrass function and the limitations can be used to describe the contact mechanics in rotor system.
- There are no experimental validations. Add it.
Response: According to suggestions of the reviewers, it will be carried out in future work.
- Part 3.1 should be revised, there are no references for equations eq.4 to eq.18, nor justifications for the material and mechanical assumptions.
Response: According to the reviewer’s comments, the corresponding references for eq.4 to eq.18 are added in the revised version.
- In part 3.2, reference 32 and 33 are quoted. However, the origin is in Majumdar, A., & Bhushan, B. (1991). Fractal Model of Elastic-Plastic Contact Between Rough Surfaces. Journal of Tribology, 113(1), 1. doi:10.1115/1.2920588. And in 32 and 33, it is not this formula because an additional term is introduced: a domain extension factor.
Response: According to this comments, the necessary modification is conducted in the revised version.
- I don't understand eq.21. nmax , is not precise? If I understand correctly, you sum all the real contact area for the nth level asperity surfaces? but many asperities for each nth surface are not in contact.
Response: In Eq. (21), ‘nmax’ stands for the sum of all the real contact area in all the asperities.
- Why limited to delta=1.34 ?
Response: The value is obtained from reference [36].
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The subject addressed is current and has interest.
The work is well structured.
The presentation of the model should be improved.
The conclusions are supported in the presented results.
I suggest the following amendments:
- On chapter 1. Introduction: in the sentence “Beer [21] respectively presented the two and three dimensional contact elements” It seems to me that the word "respectively" is superfluous in the sentence.
- On chapter 1. Introduction: please define the acronym W-M – Weierstrass-Mandelbrot at their first use.
- On chapter 2. Dynamics modeling of rod fastening rotor: in equation (1), it seems to me that the factor should be 48 instead of 384.
- In the last paragraph of chapter 2 Dynamics modeling of rod fastening rotor: in the sentence “This illustrates that first second natural frequencies…”, it seems to me that it should be “This illustrates that first and second natural frequencies…”.
- I consider thar the characterization of contact stiffness of joints interface, chapter 3, should be better explained.
- I consider that the equations 4 should be reasoned or based in literature.
- I consider that the description of Figure 4 should be more clear, such as “Fig. 4 shows the contact between a single asperity and a rigid plane”, instead of “As shown in Fig. 4, the contact between a single asperity and a rigid plane happens”.
- I consider thar the “the deformation of single asperity and the contact area" derived in equation (8), and the corresponding contact forces, in equation (9), should be better described and reasoned.
- I consider that the meaning of material hardness, H, should be defined.
- In Table 1, the specification of the “Grade of asperity n”, should be revised.
- In the sub section 4.2 Dynamic characteristics of rod fastening rotor system: I consider that the physical characteristics of the rod fastening rotor system should be better defined, namely the material of the shafts, discs and fastener bolts and the surface finish of the discs.
Author Response
Thanks for reviewers’ comments concerning our manuscript entitled ‘Dynamic characteristics analysis of a rod fastening rotor system considering contact roughness’. Those comments are all valuable and helpful for revising and improving our paper. Also, reviewers’ questions get us to think seriously about things we have never thought about before.
- On chapter 1. Introduction: in the sentence “Beer [21] respectively presented the two and three dimensional contact elements” It seems to me that the word "respectively" is superfluous in the sentence.
Response: According to the comment, the word “respectively” is deleted.
- On chapter 1. Introduction: please define the acronym W-M – Weierstrass-Mandelbrot at their first use.
Response: Weierstrass-Mandelbrot is used in the first use.
- On chapter 2. Dynamics modeling of rod fastening rotor: in equation (1), it seems to me that the factor should be 48 instead of 384.
Response: yes, the modification has been finished.
- In the last paragraph of chapter 2 Dynamics modeling of rod fastening rotor: in the sentence “This illustrates that first second natural frequencies…”, it seems to me that it should be “This illustrates that first and second natural frequencies…”.
Response: Yes, it has been modified.
- I consider that the characterization of contact stiffness of joints interface, chapter 3, should be better explained.
Response: The contact stiffness is closely related to the frequency index is established on the theory of fractal contact analysis. Meanwhile, the fractal contact is a classical theory in the mechanics.
- I consider that the equations 4 should be reasoned or based in literature.
Response: Eq. (4) is based in the literature. Please check the modification.
- I consider that the description of Figure 4 should be more clear, such as “Fig. 4 shows the contact between a single asperity and a rigid plane”, instead of “As shown in Fig. 4, the contact between a single asperity and a rigid plane happens”.
Response: This is a good suggestion. In the following research, the suggestion will be completed.
- I consider thar the “the deformation of single asperity and the contact area" derived in equation (8), and the corresponding contact forces, in equation (9), should be better described and reasoned.
Response: the equation (8) is obtained from reference [35].
- I consider that the meaning of material hardness, H, should be defined.
Response: H is defined to describe the yield strength.
- In Table 1, the specification of the “Grade of asperity n”, should be revised.
Response: According to this comment, it has been revised.
- In the sub section 4.2 Dynamic characteristics of rod fastening rotor system: I consider that the physical characteristics of the rod fastening rotor system should be better defined, namely the material of the shafts, discs and fastener bolts and the surface finish of the discs.
Response: Yes, I agree with the reviewer’s suggestion.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
ALl is OK.
