Study on the Effect Mechanism of MRD to Rotor System
Round 1
Reviewer 1 Report
The paper presents a numerical study on a Magnetorheological damper (MRD) used as a semi-active control device. A bilinear constitutive law for the internal active fluid is considered and its influence on the overall MRD behaviour is studied through a numerical model.
The obtained results are interesting and potentially useful for designers.
Nevertheless, the paper needs major modifications; the following issues must be carefully considered.
- The real novelties contained in the paper must be better specified.
- The work is only numerical; some comparisons with already published experimental results are suggested.
- More details on the motivation to adopt the bilinear constituitve law and reference to other cases published in the literature must be added.
- At the beginning of Section 2.2. it is claimed that Timoshenko beam elements are used with 2 rotational degrees of freedom in each node. This is not correct in the case of a 2D simulation. The Authors must explain.
- The manuscript needs extensive editing of English
- Mpa should be written as MPa.
Author Response
Dear Editor and Reviews,
We appreciate the valuable and constructive suggestions provided in the review reports. We have revised the manuscript and addressed the issues raised by the reviewers, which are detailed in the attachment.
Best,
Jun Wang
Author Response File: 
Author Response.pdf
Reviewer 2 Report
General observation:
MRD has been studied for a while. You point to several references, also modelling references. Can you pin point in detail what is the real new part of this paper contribution? Is it the model of the MRD itself (it seems that this has already been published before?)? Is it about the calculation of the stiffness and damping properties? The integration in the jeffcott model (most likely already done as well?)? Addition of the bearing model (to me this is not fundamentally contributing to the results)? Or is it the discussion of the results, here the most interesting part might be the non linear triggering, however this discussion is a bit poor in the paper.
Please indicate clearly the novelty of the paper.
Content :
Formula 5 : It is not clear what will be done with tc in the equations. This is a parameter related to the MRF only, or also related to the geometry of the damper and or the simulation conditions. How is it determined.
The rotor dynamic model is a general one can you give a reference where the model has been retrieved from
The link between ke and K, me and M … is not clear ans should be given.
The parameter l is nod defined. (suppose the length of a beam section
E, G and poisson ratio are not defined
A and I are not defined
Bearing model
The detailed bearing model does not contribute a lot to the discussion. It would be more relevant to give an overall stiffness and damping matrix of the bearing for the given load conditions.
Besides it is not mentioned what x and y are representing (loads on the bearing?)
How do you determine the contact angle, is this fixed or is the iterative with the applied loading? This one is load dependent ratio between the radial and axial load….for the simulation no load conditions are given.
Anyway, you should give a literature reference for the bearing model if you use it.
Result analysis:
MRD has been studied for a while. You point to several references, also modelling references. Can you pin point in detail what is the real new part of this paper contribution? Is it the model of the MRD itself (it seems that this has already been published before?)? Is it about the calculation of the stiffness and damping properties? The integration in the jeffcott model (most likely already done as well?)? Addition of the bearing model (to me this is not fundamentally contributing to the results)? Or is it the discussion of the results, here the most interesting part might be the non linear triggering, however this discussion is a bit poor in the paper.
Please indicate clearly the novelty of the paper.
For this simulation an excitation level (unbalance) should be given. I suppose this is done with the parameter e? Anyway, the unbalance is not specified in the models (via generalized forces?). Thus you should elaborate this.
The discussion on the irrational frequencies and its relation to instabilities is very poor. You should focus more in depth on the frequency content to decide where these frequencies come from and show why these frequencies are giving instability to the system. Next question would be are we far from any threshold of real instability.
Figure 6 : better to use the parameter Z and Zc as defined before in stead of L (m)
About the maximum pressure. The pressure is generated by dh/dt (see equation 7), in fact result of the vibrations. However in this section no definition I made of any rotor movement? Or is this another pressure related to the pressure generated by the activation of the MRF. Please elaborate on this.
3.1 Mechanical properties of MRD
Figure 6 : better to use the parameter Z and Zc as defined before in stead of L (m)
About the maximum pressure. The pressure is generated by dh/dt (see equation 7), in fact result of the vibrations. However in this section no definition I made of any rotor movement? Or is this another pressure related to the pressure generated by the activation of the MRF. Please elaborate on this.
3.2 the effect of MRD on the rotor system
For this simulation an excitation level (unbalance) should be given. I suppose this is done with the parameter e? Anyway, the unbalance is not specified in the models (via generalized forces?). Thus you should elaborate this.
The discussion on the irrational frequencies and its relation to instabilities is very poor. You should focus more in depth on the frequency content to decide where these frequencies come from and show why these frequencies are giving instability to the system. Next question would be are we far from any threshold of real instability.
Type errors:
Rule 99 : no reference given
Rule 106 : fulls should be fills
Fig 3 sqirrel should be squirrel
Rule 144 : word “touch”???
Rule 146 : ball should be balls
Author Response
Dear Editor and Reviews,
We appreciate the valuable and constructive suggestions provided in the review reports. We have revised the manuscript and addressed the issues raised by the reviewers, which are detailed in the attachment.
Best,
Jun Wang
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The paper has been modified as suggested and can be published on Applied Sciences after minor final check.
Author Response
Dear Editor and Reviews,
We appreciate the valuable and constructive suggestions provided in the review reports. We have revised the manuscript and addressed the issues raised by the reviewers, which are detailed in the attachment.
Best,
Jun Wang
Author Response File: Author Response.pdf
Reviewer 2 Report
the reference to the rotor dynamic model still needs to be added (Nelson ....)
Author Response
Dear Editor and Reviews,
We appreciate the valuable and constructive suggestions provided in the review reports. We have revised the manuscript and addressed the issues raised by the reviewers, which are detailed in the attachment.
Best,
Jun Wang
Author Response File: Author Response.pdf
