A Predictive Methodology for Temperature, Heat Generation and Transfer in Gigacycle Fatigue Testing

Round 1

Reviewer 1 Report

The subject of ultra-high cycle fatigue is interesting. The experimental consideration to predict heat generation and transfer is essential to make it possible to interpret the results after experimentation. The work is valuable as the author tried correlating with experiments and FE modelling. Some issues need to be addressed before the manuscript is considered for publication:

·        The introduction needs to be revised extensively. The authors mentioned some previous works, but usually, they did not to the main conclusion of each individual work and just mentioned that the experimental procedure is similar to their approach. The essential criteria regarding heat generation did not explain in detail.

·        The references list is not up to date. Just three references are from the last five years.

·        The way the authors present the introduction and the list of references used in the study is more appropriate for technical notes, and it should be amended for a journal article.

·        The Ultrasonic machine and other experimental facilities did not clearly introduce (Model, Manufacturing, etc.)

·        How could the generated heat affect the final UHCF results?

·        Almost in all figures, the caption and labels are not legible.

·        How could this prediction help the interpretation of the results? Is there any correlation in place for re-calibration of the results?

·        From the set of selected materials for the experiment, it seems the model is only valid for a specific density or elastic modulus range. It would be great if it explains and discussed in the introduction. What could be the results if Al or Ti alloy were used in the experimentation?

·        About the infrared camera, it would be great if the authors explained how they calibrate them. If they are used as infrared thermometers, then what is the accuracy? How do they report the real-time temperature, relative or absolute number?

·        A figure from testing facilities based on the procedure standard used for modulus measurements (ASTM E1876) could be helpful. The reported results did not show how the authors measured the modulus. What could be the effect of temperature on the reported temperature change range?

·        The change in temperature reports could significantly affect polymer composite materials, but I wonder how it is essential during the test of steel samples.

·        How will the experimental time (almost 30 S in most extended) be correlated with gigacycle fatigue test time?

·        How could this thermographic method affect the gigacycle fatigue test results? The novelty is not apparent based on the reported results.

·        The conclusion needs to be revised as it mentioned some important parameters but not the authors finding about the parameters they parametric study with FE modelling or experimentation.

Author Response

Thanks for the revisions and questions. 
Please find the discussion in the attached file.

Author Response File: Author Response.pdf

Reviewer 2 Report

This study was focused on the relationship between the modal damping parameter and the heat generation under the very high cyclic loading (VHCL) case. The academic background and the literature review seems to be suitable to support the claimed issue raised from authors. To enhance the quality of the current version, I would like to revise them according to the reviewer’s comments.

[1] How to derive the detailed values in equation (19)?

[2] Authors mainly focused on the fundamental frequency to show the accuracy of the proposed method. Is it sufficient to eliminate high resonance frequencies over the prediction of the heat generation under the VHCL cases? Or did you have other criterion to select the number of interesting critical resonances?

[3] How did you select the type of strain gauge? Did you have any special concerns for the selection of the strain gauge in VHCL study?

[4] Can you explain the reason of different two results in Figure 16 over candidate materials ?

Author Response

Thanks for the observations and questions. 
Please check the discussion in the attached file

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Considering all changes were implemented by the authors, I think the manuscript reached the level to be published.