Effect of Preload on the Vibrations of EHL Angular Contact Ball Bearings: Theoretical and Experimental Results

Round 1

Reviewer 1 Report

In this paper, the effects of preload on shaft vibrations supported by angular contact ball bearings are investigated theoretically and validated experimentally. The dynamic model of the shaft bearing system is modeled using Kelvin-Voigt element and vibration responses are analyzed under varying preloads. The paper is well written, however, the outcome of the paper is not clear, hence, it requires major revisions. The comments are as:  

• The vibration responses are analyzed at the 5000 rpm speed, how about the unbalanced effect of the shaft?
• Under varying pre-load conditions, will balls sizes and shapes in the load zone remain the same? Explain.
• What is the effect of radial clearance under high preload on vibration excitation?
• It has been observed in Fig. 3.6 that dense frequency spectra in y and z-directions, why? Explain these with reference to BFT.
• It is shown that ball passage vibrations are reduced 10 times in the pre-load range of 150-200 kN while vibration level increases significantly in the pre-load range of 200-500 kN, why? Explain. Also, is this a generalized response for the shaft bearing system? Explain
• The conclusion presented is generic, it should be specific.       

Author Response

Dear Editor

We, the authors of the paper, thank you and the reviewers for their valuable contributions to our study. We considered both reviewers questions and answered their requests.

Please find answer below for reviewer, in which each question is answered separately in the numbered order.

In order to keep the paper in correct size we do not add more wordings to the paper. Requested revisions by reviewers is completed. The notation used given table below, to trace to changes in manuscript,. Only a few small paragraph is added, 3 figures are labeled. All equation and figüre counters are updated acoording to request of reviewer. Besides, nomenclature and abbreviation list is controlled.

Legends : traced changes in manuscript.

Thank you very much for your consideration.

Yours Sincerely,

Ph.D. Hikmet BAL

OSTIM Technical University of Turkiye

Tel.: +90-532-260-4826

E-mail: [email protected]

Author Response File: Author Response.pdf

Reviewer 2 Report

Review of lubricants-1595732

• It is not clear what is the original/new contribution of this paper. What is new here which has not been reported before in the literature? So, a sentence to this effect should appear in the paper’s Abstract.
• What is new in this paper should also be included I the last couple of paragraphs of the Introduction of the paper.

The review of literature is quite good and reference is made to the works of Gohar, which is excellent to see.

• I think some of the newer reference material should be included, particularly those which include thermal analysis or thermal lubricated contacts. It should be noted that the current analysis is isothermal:

Alfares, M., Saleem, O. and Majeed, M., “Analytical study of thermal variation impact on dynamics of a spindle bearing system”, Proc. IMechE, Part K: Journal of Multi-body Dynamics, 2019, 233(4), pp.871-898.

Mohammadpour, M., Johns-Rahnejat, P.M. and Rahnejat, H., “Roller bearing dynamics under transient thermal-mixed non-Newtonian elastohydrodynamic regime of lubrication”, Proc. IMechE, Part K: Journal of Multi-body Dynamics, 2015, 229(4), pp.407-423.

• Gohar himself developed a 5 DOF model, which should also be cited, because its inclusion highlights what might be the new contribution in this paper. That paper of Gohar is:

Aini, R., Rahnejat, H. and Gohar, R., “A five degrees of freedom analysis of vibrations in precision spindles”, Int. J. Machine Tools and Manufacture, 1990, 30(1), pp. 1-8.

• Now with respect to this paper, it appears to me that the authors have included the effect of hysteretic damping in the second term of equation (2.7). This second term was established by Crossley and Hunt originally, which should be referenced:

Hunt, K.H. and Crossley, F.R., “Coefficient of restitution interpreted as damping in vibroimpact”, J. Appl. Mech., 1975, 42(2): 440-445.

So, a claim in improving upon work of Gohar in the above paper can be made, stating the inclusion of hysteretic damping.

• Another addition to the 5 DOF analysis of others is the inclusion of experimental work. This should also be mentioned.
• Equation and figure numbers should be in ascending order starting with 1, etc. not in the current form which f-gives the impression that this is part of a dissertation/thesis.  
• Some of the mathematical symbols used are omitted in the Nomenclature. Please make sure that the Nomenclature includes all the mathematical symbols used.
• There should also be a list of abbreviations after the nomenclature.
• I am quite happy with the results, but would have preferred spectral contributions to be market such as “cage frequency”, Ball-pass, etc in the figures.
• Figures are quite small. Please enlarge them. Also, are all these figures necessary?

This is a good paper, but I think the additions required is not very minor. I look forward to receiving any revised version with all the changes made clearly highlighted.

Author Response

Dear Editor

We, the authors of the paper, thank you and the reviewers for their valuable contributions to our study. We considered both reviewers questions and answered their requests.

Please find answer below for reviewer, in which each question is answered separately in the numbered order.

In order to keep the paper in correct size we do not add more wordings to the paper. Requested revisions by reviewers is completed. The notation used given table below, to trace to changes in manuscript,. Only a few small paragraph is added, 3 figures are labeled. All equation and figüre counters are updated acoording to request of reviewer. Besides, nomenclature and abbreviation list is controlled.

Legends : traced changes in manuscript.

Thank you very much for your consideration.

Yours Sincerely,

Ph.D. Hikmet BAL

OSTIM Technical University of Turkiye

Tel.: +90-532-260-4826

E-mail: [email protected]

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The manuscript is now modified and the quarries are replied well. 

Reviewer 2 Report

The authors have addressed my concerns and included all of my suggestions. I think the paper is very good and I recommend it for publication.