Advanced Numerical Modeling and Experimental Analysis of Thermal Gradients in Gleeble Compression Configuration for 2017-T4 Aluminum Alloy

Round 1

Reviewer 1 Report

The manuscript presents a detailed experimental and numerical investigation into the temperature gradients occurring in 2017-T4 aluminum alloy specimens during Gleeble compression tests. The study incorporates both experimental thermocouple measurements and a numerical finite element model using Abaqus with a User Amplitude subroutine (UAMP). The results of the study provide important insights into how temperature gradients influence mechanical property measurements and suggest methods to reduce these gradients, such as the use of graphite foils and improved boundary conditions.

The work is valuable for researchers and engineers utilizing Gleeble simulators for high-temperature material deformation studies, as it addresses a crucial aspect—temperature homogeneity—that can significantly affect test results. The paper is generally well-structured and provides an in-depth analysis of the results. However, a few areas need clarification or improvement.

• Ensure consistent use of terms throughout the manuscript, such as “Gleeble simulator” versus “Gleeble thermomechanical simulator,” to avoid confusion for the reader.
• In some sections, particularly in the introduction and methodology, the passive voice is heavily used, which can obscure the actions taken. Revising these sections to use the active voice where appropriate would improve the paper’s engagement.
• The description of the experimental setup is thorough, but additional context regarding the choice of parameters, such as the specific selection of aluminum 2017-T4 alloy or the anvil material, would be beneficial. The authors should justify why these specific materials and conditions were chosen, especially in relation to similar studies.
• The development and application of the UAMP subroutine are well-documented, but more detail on the limitations of the subroutine would enhance the discussion. For example, how does the subroutine handle highly nonlinear temperature profiles, and are there any assumptions that may affect the results in more extreme testing conditions?
• It is recommended that the authors discuss the computational efficiency and scalability of their model in more depth. For instance, how might the simulation time change with a larger or more complex specimen geometry?
• The PID control mechanism could be described in a slightly more accessible way, especially for readers not as familiar with control systems in thermomechanical simulations.
• The results are presented clearly, and the agreement between the experimental and numerical results is strong. However, the authors should discuss in more detail the potential causes of the remaining discrepancies between the experimental cooling curves and the numerical simulations (e.g., Figure 9). Are these discrepancies solely due to the cooling boundary conditions, or could other factors such as heat loss to the environment or thermocouple placement be involved?
• The authors touch on the implications of their results for material testing at elevated temperatures, but they should emphasize these implications more strongly. How might these findings affect future studies on materials other than aluminum, or how could the method be adapted to study other alloys?
• The conclusion adequately summarizes the key findings, but it could benefit from a more explicit statement of the study’s limitations and suggestions for future work. For example, could the authors investigate how different materials for the anvils or alternative methods for heating the specimen affect the results?
• The manuscript would benefit from a thorough proofreading to correct minor grammatical issues and improve the overall flow. For example, phrases such as “affect the accuracy of measured mechanical properties” could be reworded for better readability.

 

Author Response

Thank you very much for reviewing our article proposal for the journal Applied Mechanics. We appreciated your feedback and the questions raised. Attached, you will find the answers to your questions. The article has been revised to incorporate your comments, and a grammatical correction has been applied throughout the text. We hope this new version will be satisfactory

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper presents a robust experimental and numerical investigation into temperature gradients in compression testing. Overall, the research is technically sound and addresses an important issue in accurately measuring material properties. Therefore, I suggest that we publish it after minor revisions. To meet the publication requirements, the authors need to address the following issues:

In the introduction section:

1. The literature review could be expanded to contextualize the significance of the findings better. Although you reference relevant studies (e.g., Quan et al., Xiao et al.), a deeper discussion about their limitations and how your work addresses these gaps would provide a stronger rationale for your approach. It should be improved.

In the main section:

2. Fig. 7 and 8 could benefit from a clearer visual explanation of the temperature gradients within the specimen and anvils. The scale of temperature difference is small (<1.9°C), and it might be useful to add insets or zoom-ins in the figures to highlight these variations more clearly.

3. The discrepancies during the cooling phase are only briefly mentioned. It is recommended to delve deeper into why these differences arise and how they might affect the broader applicability of the model.

4. The paper focuses on 2017-T4 aluminum alloy. Is the method proposed in this paper applicable to other alloys?

In the conclusion section:

5. It is recommended to add a discussion on future work.

Other comments for this paper:

6. The writing is generally clear, but there are a few grammatical and stylistic improvements that could be made for better readability. For example, "The temperature fields within the specimen and anvils are analyzed" (p. 3, line 100) could be rewritten for clarity.

7. Ensure consistency in unit usage and formatting throughout the paper.

Author Response

Thank you very much for reviewing our article proposal for the journal Applied Mechanics. We appreciated your feedback and the questions raised. Attached, you will find the answers to your questions. The article has been revised to incorporate your comments, and a grammatical correction has been applied throughout the text. We hope this new version will be satisfactory

Author Response File: Author Response.pdf

Reviewer 3 Report

This paper presents an extensive description of the thermo-electrical issues related to high temperature compression tests performed with a Gleeble 3500 machine. The contribution is essentially technical and is relevant only to researchers working with such a machine. However, there is no doubt that the number of users of Gleeble machines and the relevance of the characterization performed with them are such that contributions of this kind are welcome. The novelty of the contribution stands in the demonstration of how a PID simulator can be useful to conduct well-controlled thermo-mechanical tests.  Considering the quality of the description of the experimental set-up, the originality of the methodology and how the Authors have reported their simulation works, I think this paper deserves publication.

The paper is interesting and well written.

The methodology is excellent and well-described.

 

The paper is technical essentially. There is no scientific content that is debatable.

 

Line 315: Typo error. as in introduced.

The paragraph between Lines 366 and 373 is not necessary.

Line 411: Who are the several Authors?

Author Response

Thank you very much for reviewing our article proposal for the journal Applied Mechanics. We appreciated your feedback, and the questions raised. Attached, you will find the answers to your questions. The article now incorporates your comments, and a grammatical correction has been applied throughout the text. We hope this new version will be satisfactory.

Author Response File: Author Response.pdf