Research on the Influence of the Closing Amount of Electrical Connector Contacts on Fretting Wear under a Vibration Environment
Round 1
Reviewer 1 Report
In electronics-2405318 “Research on the influence of closing amount of electrical connector contacts on fretting wear under a vibration environment”, authors present the model of the contact resistance dependence on the contact geometry and discuss the experimental data revealing the resistance rise during the mechanical vibrations of the setup. The manuscript is well-written, and overall presentation is quite colorful. However, it is mostly the theoretical model that deteriorates the impression and raises some serious questions.
Major comments:
1) For the theoretical calculation presented in fig. 8, please indicate if any parameters were adjusted in accordance with the procedure implied in lines 316-317. Were the long and short axis lengths somehow varied to obtain the plausible dependence? What was the procedure of the adjustment?
2) In fig. 8, the presentation of the data doesn't make it possible to determine if the experimental values show any trend or not. Wouldn't it be better to average the resistivity of the sockets with x_avg = 0.19-0.20 mm deflection, thus obtaining the value with 0.195 mm x position, 0.005 mm error, and some averaged y positions and errors, and repeat it for x_avg = 0.135, 0.145,... 0.185? Currently it seems like the experimental values are randomly distributed independently on the deflection.
3) Please discuss why the frequency and amplitude of the vibrations presented in Lines 345-347 were chosen for the experiments. Are their values somehow related to the factory environment?
4) In Fig. 21, the real trend of the ECR dependence on the deflection seem significantly steeper than the theoretical trend. This raises the question of the model applicability to the studied scenario. Please discuss the discrepancy between the theoretical and experimental data and determine the ways to reduce it.
To me, comments 2 and 4 indicate that the manuscript consists of 2 separated parts: the experimental studies regarding the ECR dependence on the vibration and the model which results poorly fit the stable ECR values (fig. 8, fig. 21) and doesn’t describe the ECR variation with the exposure vibration. This significantly diminishes the quality of the manuscript. If this issue will not be addressed, I will suggest that the manuscript is to be rejected.
Minor comments:
5) fig 2, "r" indicated in the left part is not identified in the text. Shouldn't it be r0?
6) fig. 2, right part: in "r2" notation, '2" should be in subscript mode.
7) Is it possible to specify the source of the information presented in Tables 1-2?
8) In eq. 1 it is unclear, why the surface is represented by two z coordinates. Additionally, A1, A2, B1, B2 should be identified in the figure 4 or in the text to make it clearer what do they represent.
9) eq. 2: please indicate what is S and why is S < 1.
10) In eq. 4, what do Theta_1 and Theta_2 symbols represent?
11) In eq. 14, shouldn't the lower limit of the integral be "h" rather than "d"?
12) Lines 230-231, rephrase "contact pair contact length".
13) Eq. 21, 22 and Fig.6: could you please comment on the physical meaning of the m parameter? Why was the 0.1-2.0 range of its variation chosen for Fig. 6?
14) Line 345: by t = 0.04s, do you imply that each experiment was carried out for 0.04 s only? As I see it, t is a variable, and its determination as a fixed parameter confuses me.
15) Lines 368-369, consider marking A-E notations in the Fig. 12.
16) I think that the details of the resistivity measurements (section 3.3.1) and deflection studies (Section 3.3.2) should be placed prior to the experimental results (for example, fig. 8) or after the experimental section.
17) In Fig. 16, in "C-2" notation, does "2" mean the number of the sample? Please specify it in the text or in the figure caption.
18) Line 463, revise "wear Flaking debris particles" fragment.
19) Line 491, what do you mean by "arranged horizontally"?
20) In Fig. 18, consider removing the bottom bar of the SEM images, as the information presented in it is not visible and redundant. Additionally, consider adding the scale bar to all of the images.
21) In Fig. 19, the scale bar identifying the meaning of the colors in the heatmap is not visible. Please increase its thickness and font size.
22) Line 436-439: "the oxide film, contamination film, and adsorption film at the contact interface were removed under the action of fretting, which increased the effective contact area, reducing slightly the ECR in the early stage". This explanation seems plausible, but don't see the manifestation of this effect in Figs. 16-17, could you show it? I suggest the enlarged fragments of the figures to be presented to show the decrease of ECR in the initial period.
23) Throughout the paper, by "precious metal", did you mean "noble metal"?
24) Line 587-588, what do you mean by "the long and short axis parameters of the contact ellipsoid were solved"? As I understand, the values of these parameters were somehow picked (see comment 1), but the procedure and obtained values of these parameters are not discussed.
Comments 12, 18, 19 ans 23 are related to the phrasing used by authors. They are minor, and I think that overall English level is good.
Author Response
Dear Reviewer, Please see the attached document.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments to the Authors:
The authors of this paper present a combined theoretical analysis and test data in order to provide a reference basis for improving the structural design of electrical connectors, optimizing the performance of electrical contacts, and improving the overall reliability design. However, some details should be considered by the authors:
COMMENT: lines 34 & 39: More recent references could also be added.
COMMENT: Some references could be added to sec. 2.1.
COMMENT: lines 308-310: Please rephrase.
GENERAL COMMENT: Much of the mathematical proofs and calculations could be included in an appendix or as separate supplementary material.
COMMENT: lines 323-324, Fig. 8 as well as Fig. 21: What is the estimated error in the ECR test values? Please add some comments.
COMMENT: A comparative discussion between SEM morphologies presented in Fig. 18 could be added.
The results support the authors conclusions. Thus, I think that this paper may be published after minor revision.
By taking into account the interest of this work, in my opinion this paper deserves publishing, after minor revision.
Author Response
Dear Reviewer, Please see the attached document.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Main comment:
In my opinion, authors have significantly compromised the presented results by the provided revision.
First of all, the description of the parameters’ adjustment provided in lines 325-328 (“Calculations can be carried out based on the structural characteristics of the contact and the actual contact, the contact ellipsoid was corrected using the contact area iterative calculation method proposed in reference [47]”) is substandard, as the English version of Ref. 47 cannot be found and apparently doesn’t exist. Therefore, significant amount of the journal readers won’t be able to assess the protocol of the investigation of the results. For the current review stage, it is essential for me to know what variables are used to find the estimated parameters, as it is unclear if the resistance values were used to assess these parameters. Please discuss the fitting procedure in detail.
Second, why is the deflection for initial ECR ranges from 0.14 and 0.18 mm? Currently it is only backed by virtual “communication with the manufacturer”, but for me it is unclear why the deflection wasn’t set to zero. Please provide a reasonable explanation.
Third, data presented in Figs. 8 and 21 seems erroneous and misleading, as, according to line 333, the deflection of the initial ICR value is unknown. Was the deflection values set up on the convenient X positions to match the fitting data? Why errors of the experimental values are not presented in the plots?
As I see it from the discussions provided in the manuscript, authors have derived the fitting values from the ICR values, and later set the deflections in Figs. 8 and 21 to obtain better correlation between the ICR values and their fitting. This compromises the suggested approach and makes it impossible to replicate it on real results. In my opinion, this puts the manuscript on the borderline to being rejected.
If the theoretical and experimental results are only fitted by “setting up” some values, consider separating the experimental and theoretical studies within the manuscript after addressing my concerns.
Additional comment:
Line 194, “where Theta_1, Theta_2 indicates material parameters”. What kind of parameters do they indicate, what is their origin and the range of their variation?
manuscript is not error-free (line 340, "decreasesd"; line 591, "se-vere"). However, the text is entirely understandable.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 3
Reviewer 1 Report
The manuscript can be accepted as is.
English is completely understandable.
