Applications of Operational Modal Analysis in Gearbox and Induction Motor, Based on Random Decrement Technique and Enhanced Ibrahim Time Method

Round 1

Reviewer 1 Report

This work reports a method for determining the structural natural frequencies, based on Operational Mode Analysis (OMA). Random Decrement Technique, and Enhanced Ibrahim Time Method (EITM) were also applied on the surface vibration signatures for detection of natural frequencies. It was also applied the Correlation Analysis (CA) which has ability to extract interesting information about the modal characteristics of the signals. After reading the manuscript in its entirety, this reviewer feels that the manuscript in the current form should be revised.

1. References are mentioned but little link to the presented topic is established in the introduction. In addition, the classic references should be cited, but some new literature also should be used to reflect novelty of the topic.
2. The quality of the graph needs to be improved, and it is not clear. Besides, the font inside the figure is too small.
3. Measurement set-up and analysis procedure needs further refinement. Can you explain the differences and innovations between this experimental setup and others.

Author Response

Reviewer 1

 

We appreciate the reviewer comments which make to improve the paper’s quality. Please, in the paper, all new or changed text is in yellow color.

 

This work reports a method for determining the structural natural frequencies, based on Operational Mode Analysis (OMA). Random Decrement Technique, and Enhanced Ibrahim Time Method (EITM) were also applied on the surface vibration signatures for detection of natural frequencies. It was also applied the Correlation Analysis (CA) which has ability to extract interesting information about the modal characteristics of the signals. After reading the manuscript in its entirety, this reviewer feels that the manuscript in the current form should be revised.

 

 

1. References are mentioned but little link to the presented topic is established in the introduction. In addition, the classic references should be cited, but some new literature also should be used to reflect novelty of the topic.

This part is extended with several papers, in order to explain extensible, the work done by the authors. The bibliography can be found in [13], [17-21]

2. The quality of the graph needs to be improved, and it is not clear. Besides, the font inside the figure is too small.

The figures 9 and 11 have been improved. They have now high resolution.

3. Measurement set-up and analysis procedure needs further refinement. Can you explain the differences and innovations between this experimental setup and others.

 

The measurement procedure has been increased with further details. Additionally, it can be worth to mention that the major contribution of this paper is not directly, the measurement set up. Otherwise the data procedure analysis, where the advanced signal processing techniques have combine to obtain the reconstructed Frequency Response Function.

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

comments mentioned in the attached file

Comments for author File: Comments.pdf

Author Response

Reviewer 2

 

Applications of Operational Modal Analysis in Gearbox and Induction Motor Based on Random Decrement Technique and Enhanced Ibrahim Time Method The present manuscript discusses a technique of operational modal analysis on gear boxes performed in running condition. The authors have performed a set of experiments and have applied EITD and RDT techniques. However, the work itself is not sufficient to establish novelty. The manuscript lacks an appropriate introduction, methodology, and result analysis. The overall writing quality is not at all up to the mark for a reputed journal. The research gap is not clearly identified and thus the need of the study. Overall, the manuscript requires some major changes in language, novelty and experimental details. The following are my observations:

We appreciate the reviewer comments which make to improve the paper’s quality. Please, in the paper, all new or changed text is in yellow color.

 

General comments:

1. The introduction is not in a good shape. The language is very difficult to comprehend and confusing in nature.

In this section, it was introduced several papers, which are in [13], [17-21], in order to improve the quality of the paper

2. The manuscript requires a go through from an English expert.

The paper was revised by and English expert.

3. The parameters involved in the equations are not explained, hence making it difficult to understand the Enhance Ibrahim Time Domain method.

This section was extending with several equations to give an overall overview of the method. The bibliography [3] was used

 

4. The figures are of very low resolution and also not presented in a descriptive manner.

The figures 9 and 11 have been improved. They have high resolution now.

 

5. Figures have very small legends and axis titles making it difficult to read.

It was performed a quality control to all figures.

 

6. The references are not properly written. For example, ref. 7 and 16 are just title of the pdf files. 7. Why the system has different natural frequencies at different speeds?

The references are now properly written. The second question is very interesting, based on the theory of the structure natural frequencies are not depending of the shaft speed. In our case at 1800 rpm, we had a frequency drift between 600 to 1100 Hz. We did have a control check with the signals to see, whether, if they are correct measured or not. They are correct measured. Sorry, but at this moment is hard to have a clear conclusion what happen.

 

Specific comments:

1. The full forms are repeated everywhere in the manuscript.

It was changed

2. Kindly mention the full form of FRF before it appears in the manuscript.

It was mention initially in the abstract section.

3. The font size in the abstract is not uniform

It was corrected

4. Line 43: Grammatically the sentence is not correct.

It was changed

5. Line 253, 259: Use a multiplication (×) symbol instead of an Asterix (*) 6. Line 307: Impotence? a typo �

It was changed

 

Author Response File: Author Response.docx

Reviewer 3 Report

The Manuscript ID applsci-1552034  Title: “Applications of Operational Modal Analysis in Gearbox and Induction Motor Based on Random Decrement Technique and Enhanced Ibrahim Time Method” belongs to the field of machine diagnostics using the vibration analysis.

 

Concerning the scientific content of the paper

1. The Introduction must be consistent, which is not, and link the aim of the paper to the research worldwide spread and accepted. The paragraph 1. Introduction must introduce the readers in the aim of the research detail by detail. For these reasons at least six papers must be added at the References and critically presented in the Introduction:

• “Operational modal analysis techniques and their theoretical and practical

aspects: A comprehensive review and introduction”  https://www.researchgate.net/publication/281786721;

• “A review of operational modal analysis techniques for in-service modal

Identification” DOI: 10.1007/s40430-020-02470-8;

• “Application of the Random Decrement Technique in Operational Modal Analysis” https://vbn.aau.dk/en/publications/application-of-the-random-decrement-technique-in-operational-moda;
• “An Overview of Operational Modal Analysis: Major Development and Issues”

https://scholar.google.ro/scholar?q=An+Overview+of+Operational+Modal+Analysis:+Major+Development+and+Issues&hl=en&as_sdt=0&as_vis=1&oi=scholart;

• “Enhanced frequency domain decomposition algorithm: a review of a recent development for unbiased damping ratio estimates”

https://doi.org/10.21595/jve.2018.19058;

• “Modal Parameter Extraction of a Huge Four Stage Centrifugal Compressor Using Operational Modal Analysis Method” http://dx.doi.org/10.1590/1679-78254117.

2. The References are very “poor” for such a subject in the field of machine diagnostics, therefore this aspect must be developed.
3. The title of the second paragraph is meaningless “ Materials and Methods” taking into account the content, I suggest another title much more appropriate “Methods and Procedure”.
4. The presentation of the methods and procedure must be improved with more details.
5. In paragraphs 3 Analysis and Results and 4 Discussion ( is better “ Discussions”) it doesn’t exist any kind of comparation with the results obtained by others researches in the field published in literature, especially in the MDPI Journals.

Concerning the presentation of the paper with respect to Manuscript Type MDPI journal template

1. The References doesn’t respect 100% the form demanded by Manuscript Type MDPI journal template, for example references : 1, 2,7,9,16.
2. Figures 1-11 caption and their title description must be left aligned, as demanded by Manuscript Type MDPI journal template, and they are not.
3. Table 1 must be left aligned, as demanded by Manuscript Type MDPI journal template, and it is not.

 

For the above-mentioned aspects, I strongly advise the major revision of the paper.

 

 

 

Author Response

Reviewer 3

We appreciate the reviewer comments which make to improve the paper’s quality. Please, in the paper, all new or changed text is in yellow color.

 

 

Concerning the scientific content of the paper

1. The Introductionmust be consistent, which is not, and link the aim of the paper to the research worldwide spread and accepted. The paragraph 1. Introduction must introduce the readers in the aim of the research detail by detail. For these reasons at least six papers must be added at the References and critically presented in the Introduction:

It was included the recommended papers, in order to improve the quality of the paper

• “Operational modal analysis techniques and their theoretical and practical

aspects: A comprehensive review and introduction”  https://www.researchgate.net/publication/281786721;

It was included in the paper

• “A review of operational modal analysis techniques for in-service modal

Identification” DOI: 10.1007/s40430-020-02470-8;

It was included in the paper

 

• “Application of the Random Decrement Technique in Operational Modal Analysis” https://vbn.aau.dk/en/publications/application-of-the-random-decrement-technique-in-operational-moda;

It was included in the paper

• “An Overview of Operational Modal Analysis: Major Development and Issues”

https://scholar.google.ro/scholar?q=An+Overview+of+Operational+Modal+Analysis:+Major+Development+and+Issues&hl=en&as_sdt=0&as_vis=1&oi=scholart;

It was included in the paper

• “Enhanced frequency domain decomposition algorithm: a review of a recent development for unbiased damping ratio estimates”

https://doi.org/10.21595/jve.2018.19058;

It was included in the paper

• “Modal Parameter Extraction of a Huge Four Stage Centrifugal Compressor Using Operational Modal Analysis Method” http://dx.doi.org/10.1590/1679-78254117.

It was included in the paper

 

2. The Referencesare very “poor” for such a subject in the field of machine diagnostics, therefore this aspect must be developed.

The bibliography was extended with 5 papers

3. The title of the second paragraph is meaningless “ Materials and Methods”taking into account the content, I suggest another title much more appropriate “Methods and Procedure”.
4. The presentation of the methods and procedure must be improved with more details.

It was included the above recommendation with a new bibliography, see papers [13], [17-21], in order to improve the quality of the paper

5. In paragraphs 3 Analysis and Results and 4Discussion ( is better “ Discussions”) it doesn’t exist any kind of comparation with the results obtained by others researches in the field published in literature, especially in the MDPI Journals.

There is no research paper that combine all the data processing technique as we worked on. However, it was performed a qualitative discussions of the standard methods with this research paper.

Concerning the presentation of the paper with respect to Manuscript Type MDPI journal template

1. The Referencesdoesn’t respect 100% the form demanded by Manuscript Type MDPI journal template, for example references: 1, 2,7,9,16.

It was corrected

2. Figures 1-11caption and their title description must be left aligned, as demanded by Manuscript Type MDPI journal template, and they are not.

It was corrected

3. Table 1 must be left aligned, as demanded by Manuscript Type MDPI journal template, and it is not.

 It was corrected

 

 

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

I have no comment for the revised manuscript. The reviewer feel that the present version can be accepted. 

Author Response

Thank you for comments and  accept the paper for publication 

Reviewer 2 Report

The authors have not correctly addressed the issue raised by the reviewers. The language needs serious improvement. The objectives are not well defined and the experiment is not well conducted or presented. Finding natural frequency using OMA is not novel.

Author Response

Dear Reviewer 2: Firstly, we want to thank your valuable comments that encourage us to be meticulous with our research work. This paper has got the following revision:

1. The paper has got an extensive English improvement. The yellow color in the text is due to the reviewer’s first time recommendations. The cian color is due to second time corrections for improvement of the paper.
2. The objectives are well defined know: “The main objective of this paper is to identify the structure natural frequencies by the regeneration of Frequency Response Functions(FRFs) for complex structures based on OMA”
3. The section of measurement set up and analysis procedure was included with detail information.
4. It`s true that finding natural frequencies are not novel by OMA. However, the main objective of our research work is to enhance the analysis procedure itself. The novelty of our research work is to combine the advantages of several methods (RDT, CFE, and ETIM), in order to obtain structure natural frequencies. It was also included the digital signal processing techniques to reduce the harmonics effects and close mode resonances The developed methodology was applied in industrial machines, such as, an induction motor and a gearbox.

Reviewer 3 Report

The Manuscript ID applsci-1552034  Title: “Applications of Operational Modal Analysis in Gearbox and Induction Motor Based on Random Decrement Technique and Enhanced Ibrahim Time Method” belongs to the field of machine diagnostics using the vibration analysis.

1. Concerning the scientific content of the paper

 

All the suggestions and remarks were satisfactorily corrected.

1. Concerning the presentation of the paper to Manuscript Type MDPI journal template

All the suggestions and remarks were satisfactorily corrected.

The manuscript can be accepted in the present form for the aforementioned aspects after some minor spelling/checking of the English language.

 

 

Author Response

Thank you for comments and  accept the paper for publication