Dynamic Analysis of Quasi-Zero Stiffness Pneumatic Vibration Isolator
Round 1
Reviewer 1 Report
This paper presents a theoretical study on a pneumatic quasi-zero stiffness isolator.
The paper is interesting and proposes a nice technical solution for isolation. However, there are several major concerns which make the paper not recommendable for publication.
1.
The abstract is too much general and does not mention about the specific innovation introduced by the pneumatic system. On the other hand, it mentions the “cylinder”, which at this stage is not known what it is.
2.
The presentation of the work is not clear and neat. The English is poor and there are several grammatical mistakes. The resolution of figures is very poor and some line styles are not even visible. There are Chinese symbols appearing randomly in the equations. There is no uniformity in font size and style throughout the whole manuscript.
3.
Figure 1 is not clear. In particular, it is not clear what is moving and what is fixed. There are several mechanical components, and the figure does not help understanding the system. This makes the paper very difficult to read since the beginning.
4.
The use of multiple scales method to solve the dynamics of isolator exploiting Taylor series approximation of the stiffness curve is well known, as well as the stability issue. It is not clear if this is a contribution of the paper or not, since the authors present a long detailed derivation of the equations.
5.
The stability issue is only slightly touched in the manuscript, and is not emphasized in the frequency response curves of figure 9 and 15. A numerical validation of the solution to the equation of motion without approximation should be presented to validate the analytical results and stability.
6.
A relatively complex model of friction is used. The are two main concerns related to this. The first is that it is not clear why the authors seek for optimal values of the friction model, if no experiment is conducted. The second issue is that the assumption for such a friction model would indeed need some experimental work. It is not relevant to this reviewer to treat a complicated phenomenon like friction using theoretical assumptions without experiments.
7.
The performance of the isolator are not shown in terms of transmissibility and it is not compared to other implementations of quasi-zero stiffness isolators. What would be the benefit of using the proposed implementation over others?
8.
In fact, the literature review on the state of the art is not complete. Acknowledgments to other isolation systems using pneumatic springs should be expanded, as well as to the way in which quasi-zero stiffness is commonly realized using classical coil springs and linkages.
9.
Are the numerical values of the parameters used to plot the figurea reasonable and physically meaningful for a practical engineering implementation? I believe that the complex dynamics would be much reduced for practical values of damping and friction in a physical prototype.
Author Response
Dear Reviewers
We would like to thank you so much for your valuable, useful comments and recommendations as well as positive acknowledgment on our manuscript. Under the guidance of your professional suggestions, we have carefully checked and corrected to enhance the quality of the paper. All changes in the new version have been marked by red highlighted tool. We hope to meet with the approval from Reviewers.
Best regards
Le Thanh Danh
Author Response File: 
Author Response.pdf
Reviewer 2 Report
I read the paper with great interest. This paper can be considered for publication if the authors incorporate the following suggestions in the paper.
The abstract is lengthy and some abbreviations are given without explanation.
The keywords should be up to 5.
The presentation and writing of the paper should be improved.
The novelty and gap of research should be explained in more detail. What is the significant addition in the literature?
The sensitivity analysis if applicable should be added to the paper.
The simulation study should be added and results should be compared with the existing studies.
The real example should be added and discussed with the existing studies
What are the limitations of the study?
What are the potential applications of the proposed study?
Neutrosophic statistics is the extension of classical statistics and is applied when the data is coming from a complex process or from an uncertain environment. The current study can be extended using neutrosophic statistics as future research. The statement that the proposed study can be extended for neutrosophic statistics can be added by citing some papers on neutrosophic statistics.
Author Response
Dear Reviewers
We would like to thank you so much for your valuable, useful comments and recommendations as well as positive acknowledgment on our manuscript. Under the guidance of your professional suggestions, we have carefully checked and corrected to enhance the quality of the paper. All changes in the new version have been marked by red highlighted tool. We hope to meet with the approval from Reviewers.
Best regards
Le Thanh Danh
Author Response File: Author Response.pdf
Reviewer 3 Report
- The formatting should be fixed as the equations are hardly readable in the pdf due to some random obstructing characters. Some figures are hardly readable due to poor quality (Fig. 2a, Fig. 4a, Fig. 6a)
- The type of the used friction model is not provided correctly (ln 454). Actually, Eq.2 presents the steady-state friction model given by (Armstrong, 1991).
- Conclusions simply states what was being done, however, the interpretation and significance of the results are not presented.
- Practical applicability of the results should be discussed in the conclusions.
- Some sort of experimental validation of the presented research is recommended.
Author Response
Dear Reviewers
We would like to thank you so much for your valuable, useful comments and recommendations as well as positive acknowledgment on our manuscript. Under the guidance of your professional suggestions, we have carefully checked and corrected to enhance the quality of the paper. All changes in the new version have been marked by red highlighted tool. We hope to meet with the approval from Reviewers.
Best regards
Le Thanh Danh
Author Response File: Author Response.pdf
Reviewer 4 Report
Actually, I have reviewed this manuscript for another Journal one months ago. The authors, however, have not made any revision on the manuscript apart from a new title. I would like to paste the original comments for this manuscript again as follows.
This presented research work is a continuation of a research paper carried out by the same team. The key difference between these two works is the stiffness feature of the quasi-zero-stiffness system. This manuscript analyzed a quasi-zero-stiffness system with asymmetric stiffness feature, but a symmetric one in the previous paper. Both the static and dynamic characteristics of the asymmetric quasi-zero-stiffness system, especially the effect of the system parameters on these characteristics are analyzed in detail in this manuscript. Although the manuscript looks rich and informative, I still do not recommend the publish of this manuscript
in such a high-level journal in its current version.
The following are some reasons/comments for helping me to make this decision:
(1) Authors stated that this research can offer a useful insight to design low frequency vibration isolation systems. However, authors did not carry out any research work about the low frequency vibration isolation performance. Additionally, it is suggested that a prototype is build and tested so that the main conclusions can be verified experimentally.
(2) Up to now, lots of quasi-zero-stiffness mechanisms have been proposed to achieve good vibration isolation performance in the low frequency range. Compared with those proposed isolators, what are the main advantages of the quasi-zero-stiffness isolation devised in this paper? Have a compact structure or better vibration isolation performance?
(3) Please explain the abbreviations when they are used for the first time, for instance, “SCM” and “SC”.
(4) In figure 1: the sort order of the components of the quasi-zero-stiffness isolation is confusing, that is, the number 3 appears twice.
(5) Please explain the reason that obtaining the stiffness expression (Eq. 8) by differentiating restoring force expression with respect to time (The first sentence below Section 2.2).
(6) Please give an explanation or an expression of the percentage of error of the stiffness (Fig 3b).
(7) What is the unit of the Y axis in Fig. 6b?
(8) The fifth row above Eq. 14: what is the definition of the variate of “Ze”? Is it the same as the normal “Ze”? If so, authors should carefully proofread the manuscript and unify all normal and italic variates.
(9) There are many confusing expressions in the manuscript, for instance, “is are determined” in first sentence above Eq. 1; “considered to analyzed” in second sentence above Fig. 4; “the asymmetric of the system” in third sentence above Fig. 12.
Author Response
Dear Reviewers
We would like to thank you so much for your valuable, useful comments and recommendations as well as positive acknowledgment on our manuscript. Under the guidance of your professional suggestions, we have carefully checked and corrected to enhance the quality of the paper. All changes in the new version have been marked by red highlighted tool. We hope to meet with the approval from Reviewers.
Best regards
Le Thanh Danh
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
This paper shows simulated results for a quasi-zero stiffness isolator using a pneumatic cylinder.
The following points should be addressed by the authors to improve the paper.
1.
Runge-Kutta numeric validation should be reported in all frequency response curves reported in the paper.
2.
Stable and unstable branches should also be shown for all frequency response curves reported in the paper.
3.
Please indicate in details which is the friction model adopted in Amesim.
4.
There are a series of coupling components in the systems, such as joints, sliding parts and so on, which could involve self-locking or friction locking effects, as discussed for example in:
- Self-Locking Avoidance and Stiffness Compensation of a Three-Axis Micromachined Electrostatically Suspended Accelerometer, Sensors 2016, 16, 711
- On the detailed design of a quasi-zero stiffness device to assist in the realisation of a translational Lanchester damper, Mechanical Systems and Signal Processing 164 (2022) 108258.
I believe a brief discussion is needed to inform the reader, of the potential practical effects.
5.
Recent studies in the literature have shown that quasi-zero stiffness effect could be realized by using simpler structures inspired by biological systems such as T-shape, X-shape and K-shape configurations, as discussed for example in
- Bio-Inspired Vibration Isolation: Methodology and Design, Applied Mechanics Reviews, Vol. 73 / 020801, see the full diamond in Fig- 1(c)
- Optimizing elastic potential energy via geometric nonlinear stiffness, Communications in Nonlinear Science and Numerical Simulation 103 (2021) 106035, see half-diamond in Fig.1
- Analysis and design of a novel and compact X-structured vibration isolation mount (X-Mount) with wider quasi-zerostiffness range, Nonlinear Dynamics 101(4), pp. 2195-2222, 2020
I believe a brief discussion is needed to give the reader a broader overview.
Author Response
Dear Reviewers
We would like to thank you so much for going through our manuscript carefully. Following your valuable, useful comments and recommendations, we modified this manuscript to enhance the quality of the paper. All changes in the new version have been marked by red highlighted tool. We hope to meet with the approval from Reviewers.
Best regards
Ngoc Yen Phuong Vo , Thanh Danh Le
Author Response File: Author Response.pdf
Reviewer 2 Report
Some comments are answered only in the response letter and not added to the paper. Some questions are not answered.
Please see the previous report
Author Response
Dear Reviewers
We would like to thank you so much for going through our manuscript carefully. Following your valuable, useful comments and recommendations, we modified this manuscript to enhance the quality of the paper. All changes in the new version have been marked by red highlighted tool. We hope to meet with the approval from Reviewers.
Best regards
Ngoc Yen Phuong Vo , Thanh Danh Le
Author Response File: Author Response.pdf
Reviewer 3 Report
I have no further comments
Author Response
Dear Reviewers
We would like to thank you so much for going through our manuscript carefully. Following your valuable, useful comments and recommendations, we modified this manuscript to enhance the quality of the paper. All changes in the new version have been marked by red highlighted tool. We hope to meet with the approval from Reviewers.
Best regards
Ngoc Yen Phuong Vo , Thanh Danh Le
Author Response File: 
Author Response.docx
Reviewer 4 Report
The authors have addressed all my concerns. This paper is recommended to be accepted.
Author Response
Dear Reviewers
We would like to thank you so much for your acceptation
Best regards
Ngoc Yen Phuong Vo , Thanh Danh Le
