Airtightness Sealing Performance and Failure Mechanism of the Circumferential Joint in the Low-to-Vacuum Maglev Segment Tunnel
Round 1
Reviewer 1 Report
The study introduced a apparatus to investigate the mechanical behavior and airtightness sealing capacity of the gasket-in-groove. It utilized a finite element analysis model to explore the sealing performance and failure mechanism. Findings from both experimental and numerical methods were discussed and compared, leading to several observations. Overall, the study provides insights into the mechanical behavior and sealing performance of the gasket-in-groove, emphasizing the influence of gasket compression, vacuum pressure, and the relationship between maximum contact pressure and sealing failure. The findings also highlight the importance of considering microscopic surface characteristics when utilizing FEA for evaluating sealing capacity. However, based on the questions, suggestions, and concerns raised during the review, the reviewer suggests that a major revision of the manuscript is necessary before recommending it for publication. It is important to address the raised points, provide additional information where needed, and improve the clarity and comprehensibility of the study.
A. Figure 1(a) does not accurately represent the experimental testing model shown in Figure 1(b). There are noticeable discrepancies in the physical model, such as imperfect inner circles and varying shapes and sizes of grooves between the outer and inner circles. It is important to clarify whether these differences have any impact on the numerical analysis, experimental testing results, and their comparison.
B. The engineering properties listed in Table 1 lack deterministic values. For instance, the meaning of "hardness range" and its degree of 67 is unclear. Additionally, the test strength is specified as greater than or equal to 350%. The manuscript does not define the antimildew level or its relevance to the engineering context. Furthermore, this value is vaguely described as greater than 1. It is necessary to provide specific and deterministic values for the engineering properties. What does the compression deformation percentage mean as an engineering property rather than using compressive strength?
C. Due to the excessive number of triangular elements present in Figure 4, it is challenging to verify the discretization of the analysis domain. In order to assist readers, it would be beneficial to provide enlarged depictions of the discretization around critical areas.
D. Figure 4 displays two distinct colors, but the specific differences between them are not adequately explained. It would be beneficial to provide further clarification regarding the variations represented by these colors.
E. It states that the utilization of "nonlinear adaptivity for meshing" in the simulations; however, no references or explanations are provided to support this claim. Including additional information would enable readers to assess the feasibility of finite element analysis (FEA) in a more comprehensive manner.
F. FEA employs a highly nonlinear stress-strain relationship. To enhance reader understanding, it would be beneficial to include not only the stress-strain diagram of the material but also provide details about the constitutive model employed in ANSYS. This additional information would aid readers in comprehending the specific methodologies utilized in the analysis.
G. The explanation of contact pairs in the context of this discussion is not entirely clear. It would be helpful to provide further clarification on how contact pairs work, specifically in relation to the notation used, such as 'A1-F6'. For instance, does 'A1-F6' indicate contact between the surface represented by A1 and the surface represented by F6? To enhance reader comprehension, it is recommended to include diagrams or figures illustrating some of the contact pairs, which would facilitate understanding of the different combinations and their significance in the analysis.
H. In line 256, it is mentioned that "The FEA simulations match the experimental results very well..." However, upon examining Figure 7, it appears that there are significant discrepancies, with errors exceeding 5-7%. It would be helpful to clarify the specific criteria used to determine the level of agreement between the numerical and experimental results. By providing information about the criteria employed, readers will be able to understand the basis for concluding whether the results are considered a good match or not. Additionally, it is important to note that the validation of the FEA model should encompass a mesh convergence study, involving variations in the number of finite elements and element types used. Without conducting a comprehensive parametric study, providing testing details, and establishing clear criteria for validating the FEA model, it becomes challenging to ascertain whether the model accurately represents the mechanical behavior of the apparatus. Such investigations are essential for assessing the reliability and accuracy of the FEA results and ensuring their correlation with the experimental findings.
I. Furthermore, the manuscript lacks details regarding the experimental testing, such as the number of tests conducted and the variations observed in the outcomes. It would be beneficial to include information on the experimental setup, the number of repetitions or samples tested, and any variations observed in the results. Providing these details would offer readers a more comprehensive understanding of the experimental data and its reliability, allowing for a more informed assessment of the agreement between the experimental and numerical findings.
Minor editing is encouraged
Author Response
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Reviewer 2 Report
The study on the " Airtightness sealing performance and failure mechanism of the circumferential joint in the low-to-vacuum maglev segment tunnel" is interesting however the manuscript can be improved by attending to the following remarks:
-change the keyword " maglev segment tunnel and sealing failure mechanism." to another one, since this word is in the title.
Author Response
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Reviewer 3 Report
Dear authors,
The reported work is of interest to the scientific community. I suggest making some changes based on the following comments:
-The abstract looks like conclusions. It must be improved.
-References 1-8 are missing. Please correct this.
-Does the device invented in this work have a patent or something related to intellectual property?
-Could the proposed approach be used for systems other than maglev segment tunnels?
-Line 134, EPDM is for Ethylene-Propylene-Diene Monomer.
-The engineering properties of table 1 were measured, or were they obtained from literature?
-Line 152, delete ")"
-The gasket is considered a hyperelastic material, but it is also viscoelastoplastic. The authors make assumptions to develop the FEA model, but I don't understand why limit themselves?
-Support the following with references: line 267, "the FEA may overestimate the sealing capacity of the gasket-in-groove, which is possibly related to the microscopic rough morphology of the gasket surface".
-The phrase between parentheses on line 305 can be left normal.
-There is no equation 7.
-In general, a grammar check can help improve the reading of the manuscript.
-Numerical values must be added to the conclusions. They are merely descriptive.
-What is the perspective of this work?
-It should be clarified if the study is static, since the comparison between FEA and the experimental seems to be good. An interesting point to discuss is that it could be obtained from cyclic loads or the effect of fatigue.
None
Author Response
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Round 2
Reviewer 1 Report
The reviewer appreciates the authors' efforts in addressing the reviewer's comments. However, upon closer examination, the reviewer has been unable to locate relevant responses at the specific line numbers indicated by the authors in their rebuttal. It is essential that the rebuttal be thoroughly and carefully prepared to ensure that the revisions and incorporation of comments and concerns are clearly evident to the reviewer. As the revised manuscript does not adequately address the reviewer's previous comments, the reviewer is unable to recommend the manuscript for publication at this time.
It is okay
Author Response
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Reviewer 3 Report
Manuscript is well revised by the authors and all the corrections and suggestions are incorporated in the revised manuscript, so it is accepted in the current format by my side.
Author Response
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