Simulation Analysis and Experimental Verification of the Locking Torque of the Microgravity Platform of the Chinese Space Station

Round 1

Reviewer 1 Report

The authors’ present a method of evaluating the locking torque of the Microgravity Platform of the Chinese Space Station by combining theoretical and experimental approaches. The application is novel while the combination of the theoretical and experimental methods is scientifically interesting. However, according to the reviewer’s opinion the manuscript requires some improvements. The following comments should be taken into consideration:

 

Section 3: At least one citation should be provided since the adopted theorem is standard.

 

Did the author’s consider any mass variation phenomena due to the changes and interaction within the space environment?

 

Not enough detail is given about the FEA model (materials, type of elements, boundary conditions, mesh density, etch). Which is the actual problem domain that is discretized and simulated?

 

Failure due to the contact between the locking surfaces is not investigated. The computation of the maximum von Misses Stress in the main structure is not enough to prove the safety of the locking mechanism.

 

Please if possible provide some mode shapes of vibration.

 

How the damping ratio ζ was chosen?

 

The authors mention that “the rigid unit RBE2 is used to simulate the locking state”. However, it is well known that any mechanical part even a locking mechanism has a compliance (1/k) which affects the whole system vibration. Perhaps for a space application where precision is a must, such contributions should be taken into account.

 

Section 5.2. Vibration Experiment: What if more than one repeating experiment was performed? Would the acceleration response (and equivalently the structural connection state) remain stable enough?

 

Please correct some typos/inconsistencies throughout the text. For example:

The symbol of mass should be written in italics throughout the manuscript.

f subscript should be explained, t symbol also.

Provide adequate space between symbols and text.

All symbols should have the same size.

Please rephrase the sentence: “…and the right locking device will separate and emergence

of gaps”,

etc…

Author Response

Dear Reviewer,

 

See the attachment for the response file.

 

Best Wishes.

 

Dr. Luo

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript " Simulation Analysis and Experimental Verification of the Locking Torque of the Microgravity Platform of Chinese Space Station" presents the results of an analytical, numerical and experimental study of the locking torque to be applied to a part of the Chinese Space Station. From my point of view the paper is well organized and the study is of high quality. Before being accepted for publication, I would recommend some modifications and some clarifications.

Comment 1: STRUCTURE OF THE SPACE STATION

I am not expert at all in Space Stations, and I am not familiarized with the terms included in this paper. Therefore, it is not clear enough for me the structure of the Chinese Space Station. I would like to see a better figure that includes all the parts mentioned in the paper, such as:

MP, SEC, MSHML. I have some questions:

I am not sure if the MSHML is a part of the SEC or is the same thing.

Is the MP in the core of the Space Station or is it fixed to the side wall or maybe these two concepts are the same?

In figure 2, where is the l/R mechanicsm exactly? I think that this is a very important issue.

Comment 2:  FREQUENCY RESPONSE ANALYSIS

Regarding table 1, in the second line, the magnitude for the first column is in mm, and the rest is in g, why?

I do not understand exactly the results of the frequency response analysis, it is said that the preload force Fs is obtained, eq (12), but there is no value of this force. So, this Fs force is useful or not?

And then, in table 2, the locking force of 8 positions is presented. How is this locking force obtained? Could you explain it? And it is not clear for me which are those 8 positions. Are the ones that appear after in Figure 5, please could you explain this?

 

Comment 3: STATIC ANALYSIS

It is said that 8000N is applied on both sides of the L/R mechanism. Why 8000N? Is it the result of applying 2000N to the four positions in each side? It would be very nice if Figure 6 could be presented with higher definition, is quite difficult to see where is exactly the point of the maximum tension. And  I think that the definition of the applied force is also important:  is the forces distributed from an external point to the four points? Or is it defined as a punctual force in each one? This can affect to the result, as you know.

Author Response

Dear Reviewer,

 

See the attachment for the response file.The changes have been marked in Word in the form of "Track Changes" function. PDF is the final version.

Best Wishes.

 

Dr. Luo

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

All of my recommendations have been incorporated into the manuscript and, thus, I recommend publication of the paper in its current form.

Reviewer 2 Report

  Authors have done appropriate corrections and answered all queries appropriately. The paper can be accepted.