Thermo-Mechanical Identification of Orthotropic Engineering Constants of Composites Using an Extended Non-Destructive Impulse Excitation Technique

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

 

This manuscript studied the thermo-mechanical identification of orthotropic engineering constants of composites using an extended non-destructive IET. The identification method was conducted by Resonalyser procedure. However, there are several questions and suggestions.

1. the manuscript exhibited an application and operationof IET methodand procedure, whether the relevant theories and methods were mature?
2. Can themethod test anykinds of material, and what are the specific requirements for materials and specimens? Is there any requirement for the thickness of the board and beam.
3. How are digital twins implemented? The digital twinning process and results are not shown in this manuscript.
4. The experimental results were not compared with other methods, such as FE method and conventional mechanical test. How accurate was the identification method?

Comments on the Quality of English Language

The experimental results are not expressed in the abstract. It is suggested that the abstract should express the main research contents and results of the manuscript.

Author Response

Dear reviewer, thank you for your comments and suggestions. For our answers, please see the attachment MSWord File.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

Comments:

1. The literature review provides a broad discussion of previous works, but some references lack direct connections to the presented method. For example, the discussion on EMA and OMA could be linked more explicitly to the current study.
2. Several references, such as [20] and [43], are mentioned but not critically analyzed. The review would benefit from discussing their limitations and how the proposed approach addresses them.
3. Some concepts are repeated multiple times, such as the advantages of IET. Streamlining the discussion would enhance conciseness.
4. The explanation of temperature effects on damping properties is interesting but would be more effective if supported by additional citations.
5. It is suggested to explain mor about the concept of heat transfer in orthotropic composite materials. Introducing the following review paper is useful: A Comprehensive Review on Multi-Dimensional Heat Conduction of Multi-Layer and Composite Structures: Analytical Solutions, Journal of Thermal Science30,1875-1907, 2021
6. The discussion of damping measurement uncertainties is informative but does not clarify how the proposed method reduces these uncertainties compared to existing techniques.
7. The review of micromechanical models could benefit from an explicit comparison to experimental methods, highlighting why direct measurement is preferred.
8. The literature review could better emphasize the novelty of the automated excitation mechanism compared to previous experimental approaches.
9. The methodology is well-detailed, but the mathematical formulation in Equations (1) and (2) would benefit from a clearer introduction to the symbols and their physical meanings.
10. The discussion on the pendulum excitation system is useful, but the explanation lacks a quantitative assessment of impact force variations.
11. The automated temperature control strategy is described, but it is unclear how it compares in efficiency to alternative methods such as infrared heating.
12. The manuscript does not explicitly address how the method could be adapted to different composite structures beyond thin plates.
13. The uncertainty quantification method relies on previous studies but does not provide new experimental validation within this work.
14. The damping measurement approach is discussed, but additional discussion on frequency-dependent damping characteristics would be beneficial.
15. The paper claims that the proposed method is more cost-effective than alternatives, but no cost analysis is presented.
16. The figures are well-labeled, but Figure 10 could be improved with additional annotations to clarify its significance in temperature control.
17. It is suggested to discuss more about temperature distribution in composite materials. The following analytical paper is beneficial in this regard: Journal of Heat Transfer 137 (10), 101701
18. The discussion section mentions that damping is difficult to measure, but a direct comparison to a benchmark method (e.g., DMA) would strengthen this argument.
19. The conclusion states that the method enables material characterization in future research, but potential limitations or improvements should be briefly mentioned.

Comments on the Quality of English Language

There are some grammatical inconsistencies throughout the text. For example, in the introduction:
"Composite materials have revolutionized the way vehicles, construction parts and consumer goods are designed."
A comma is missing after "parts":
"Composite materials have revolutionized the way vehicles, construction parts, and consumer goods are designed."
Additionally, the phrase "like discussed by Jones [1]" should be rewritten as "as discussed by Jones [1]."
The manuscript also contains several spelling inconsistencies, such as "frequencies match the measured frequencies" (redundant phrase) and "heterogeneities" (which could be reworded for clarity).

Author Response

Dear reviewer, thank you for your comments and suggestions. For our answers, please see the attachment MSWord File.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The study is presented very rigorously and written in high quality.  Temperature effect on the thermoplastic properties of composite is vividly observed by the proposed method.  The main comments are listed below for moderate revision.

• The “orthotropic engineering constants” can be specified.
• The automation of testing method is not well explained, such as “pendulum exciting mechanism and creating digital twins of the test sheets”.
• For “The procedures for obtaining temperature dependent elastic properties by using tensile and flexural tests are complex and time consuming.”, some numerical ‘virtual’ experiments may address this issue, such as micro computed tomography based finite element analysis. The authors refer to the latest articles talking about the advancing methods of composite measurement.:  (a) “Effect of internal defects on the thermal conductivity of fiber-reinforced polymer (FRP): A numerical study based on micro-CT based computational modeling, Materials Today Communications, 36, (2023) 106446” (b) "Numerical reconstruction of graphite/epoxy composite microstructure based on sub-micron resolution X-ray computed tomography." Composites Science and Technology 105 (2014): 174-182.
• The objective sentence “This paper describes an extended IET procedure with automated excitation for continuous identification of engineering constants across different temperatures, aiming to make the process straightforward and cost-effective.” is weakly explained in the introduction section. How is the IET procedure improved form this study?  Automated excitation may be interesting, but this is not an achievement from scientific view.
• In Figure 4, it would be better to showcase the Resonalyser during the test, not just the frame and the computer. The boundary setting of the tested beam and plate would be more interesting.
• The orthotropic properties are not properly shown in graphs and mentioned in the text.
• The technical advantages of the extended IET over the traditional IET are not well stressed in the discussion section.

Author Response

Dear reviewer, thank you for your comments and suggestions. For our answers, please see the attachment MSWord File.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The author has revised as suggested and  answered the reviewer's questions.  The manuscript can be sccepted in present form.