Ultrasonic and Conventional Fatigue Endurance of Aeronautical Aluminum Alloy 7075-T6, with Artificial and Induced Pre-Corrosion
and Nenad Gubeljak 2Round 1
Reviewer 1 Report
In this work the authors analysis the ultrasonic and conventional fatigue endurance of aeronautical aluminum alloy 7075-T6, with artificial and induced pre-corrosion. The research appears to be efficiently done and appropriately reported. The English text maintains very poor and needs review by a profitable professional in English. Nevertheless, there some questions and corrections that must be answered to improve and complete the document.
In present paper the authors describe, in the introduction, the influence of the surface roughness and pitting corrosion on the parts fatigue life. However, they don’t refer anything about possible solutions to these problems, for example, the effect of shot peening on the fatigue strength and pitting corrosion. I suggest them to consult some references about this subject, I suggest two, among others, one has the DOI: 10.1016/j.surfcoat.2010.04.015 and the other DOI: 10.1111/j.1475-1305.2009.00653.x.
Line 81- See the formation of the Figure 2 legend.
Line 89- Please, change in the sentence “… between 35 and 55% …” to “… between 35 to 55% …”.
Linees 100 and 101- Please, change in the sentence “… between 0.5 and 20Hz …” to “… between 0.5 to 20Hz …”.
Line 102 Please, change in the sentence “… temperature and without …” to “… temperature without …”.
Line 107 Please, change in the sentence “… average of roughness …” to “… average roughness …”.
Line 109- Please, change in the sentence “… which are base …” to “… which are the base ...”.
Lines 113-114- The authors describe the procedures to drill the “two artificial pits”. However, they must add more information like, who drilling machine (brand and model) and driling tool (brand and reference) were used in these experimental procedures.
In Figures 8a) and 19, the images should be provided in higher resolution to clearly read the results.
Author Response
In attached file
Author Response File: 
Author Response.pdf
Reviewer 2 Report
- Fig 2, Modal analysis requires horn and amplifier to make sure the 20KHz.
- Conventional fatigue test results at different loads should be added because of the title.
- It would be better to include the previous research results of the different researchers on 7075 aluminum studies on Fig 9.
- I don't see any specific reason why table 3 is needed.
- If you needed, the specimens for VHCF are also need to be compared before and after.
Author Response
In attached file
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for Authors
1. Fig 2, Modal analysis requires horn and amplifier to make sure the 20KHz.
Response: The horn and amplifier are calculated from the design and fabrication process and vibrate at the longitudinal frequency of 20 kHz (± 300 Hz); it comes to assure that dimensions of testing specimen are in resonance with the horn and amplifier. The last condition is achieved by modal numerical analysis as shown in Figure 2. In addition, the resonance condition is verified physically with thermographic camera, as shown in Figure 20. If the testing specimen is not in resonance, the machine stops, as is the case when specimens break.
==> It is correct that the horn and amplifier should be included in the analysis because the design of the specimen was verified by analysis. In addition, the measurement of the dynamic young's modulus, which is essential for specimen design, is not mentioned in the paper, so it is necessary to be included.
3. It would be better to include the previous research results of the different researchers on 7075 aluminum studies on Fig 9.
Response: The Fig. 9 is quite dense of experimental points; fatigue results of other study are referred and compared in the Discussion section.
==> The reason I mentioned this problem is that there has been a lot of research on the 7075 ultrasonic fatigue test, which is not in the intro part. You mentioned the case of VHCF-A, but there are some experiments after corrosion, so it would be a good idea to add a review of it to the intro.
4. I don't see any specific reason why table 3 is needed.
Response: Table 3 illustrates the variation of roughness comparing the parameter Ra before and after the conventional fatigue tests, as stated in the Introduction section.
5. If you needed, the specimens for VHCF are also need to be compared before and after.
Response: The measure of roughness for ultrasonic fatigue tests will be undertaken for a future study.
==> Still I don't see any reason why the table 3 needed. Authors should conduct a sufficient analysis of it and add the results to the conclusion.
Author Response
In attached file.
Author Response File: Author Response.pdf
Round 3
Reviewer 2 Report
comments were tried to be answered.
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
The paper fits to the scope of the journal in general and is easy to read. Nevertheless I missed a sufficient amount of novelty and especially scientific quality for a journal publications. Furthermore the chosen experimental parameters are not well explained and traceable for the reader.
Some remarks:
Materials and methods:
What is about tolerances of the specimen geometry and related scatter of the eigenfrequency for the longitudinal mode around 20 kHz. It should be clear that not each and every samples will show 19929 Hz! Furthermore waht is about the influence of the pits (modal masses?) on the eigenfrequency.
How was the stress of 44 MPa measured, validated and controlled during cyclic testing? What is about alignment and corresponding (constant?) stress conditions for the fully reversed push-pull fatigue experiment?
No dimension in Figure 5 for both geometries. That´s really a No-Go!
Fig. 6 Which stress is plotted, stress amplitude, maximum stress, von-Mises stress??? What is about run-outs? Please also try to use easy labeling, so 10E3 to 10E9.
Table 3 is really exhausting.
3.3. Numerical simulation
displacement of 130 µm: definition is peak-to-peak value or really the amplitude, the value is really high.
Fig. 8 Labeling is not visible.
Page 10 an 11: Equation 6 and 8: Please revise "a??"
Author Response
Please, find in attached file the "response to reviewer"
Author Response File: Author Response.pdf
Reviewer 2 Report
In this work the authors analysis the ultrasonic and conventional fatigue endurance of aeronautical aluminum alloy 7075-T6, with artificial and induced pre-corrosion. The research appears to be efficiently done and appropriately reported. The English text is very poor and needs review by a profitable professional in English. Nevertheless, there some questions and corrections that must be answered to improve and complete the document.
In the abstract there are some mistakes: third line the hole diameter has wrong units; fifth line, the sentence “… international norm ESA…” is not correct, please change to “… international standard ESA…”; the word “modality” in the sentence is not the most adequate, please change it to another more suitable.
Introduction: In line number 39 (page 1) I recommend the authors change “… A principal ….” To “The main …”.
Materials and methods: please change in line 54, “… the principal mechanical…” to “… the main mechanical…”.
In Figure 2, the authors depicted the result of modal analysis, however, they don't indicate nothing about the numerical simulation: used software (branch and version), number and type of elements, boundary conditions, among others. Please, complete this information in your paper.
Table 2, change the word “Principal” to “Main”.
In the Fig. 3 and 4 the authors must represent some figures to help the understanding the position of the specimen in the machines and zooming these regions.
Lines 106 and 107, the authors written that the specimen B and C have two artificial pits, but, how did they do the artificial hemispherical pits? Please indicate I the text the way used to make these pits.
Lines 116 and 117, the authors written about the use of pre-corroded specimen in their experiments, but, which the corrosive was used to pre-corroded the specimen? Please, include this information and the description of the corrosion test implemented in this work.
In the numerical simulations, the authors don't give any information about the used software, the number and type of elements, and the boundary conditions. Specially for the results presented in Figs 7, 8 and 9. They must include this information.
Author Response
Please, find in attached file the "response to reviewer"
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I do not see the needed improvement...
Author Response
- I just had a quick look, and i can see the abstract need to be improved, in which it is lack of the information for what are main results of this manuscript.
Response: Main results are pointed out in the abstract, as suggested by the reviewer.
- I do not see the needed improvement...
Response: English has been improved.
Reviewer 2 Report
The second version of the manuscript improved significantly when compared with the first version. So, in my opinion, the second version of the manuscript improved significantly when compared with the first version.
Author Response
The second version of the manuscript improved significantly when compared with the first version. So, in my opinion, the second version of the manuscript improved significantly when compared with the first version.
Response: We highly appreciate the comments of the reviewer.
English language and style are fine/minor spell check required
Response: English language and style checked
