Temperature Patterns in TSA for Different Frequencies and Material Properties: A FEM Approach
Round 1
Reviewer 1 Report
This article presents a numerical study about thermoelastic stress analysis (TSA), considering isotropic and orthotropic materials. This study is interesting and contributes for TSA related technologies development. However, the formulation presented is not for anisotropic materials but for orthotropic materials. Also, the comparisons done should be better explained, as the main assumptions considered.
The manuscript structure is adequate. Adopted bibliography can be more comprehensive. The text should be carefully revised to improve the English writing, since that several sentences are not clear. Some figures required higher resolution and the technical drawing should be improved.
It is considered that this article is in the scope of the Mathematical and Computational Modelling in Mechanics of Materials journal, but it is proposed a major revision before its possible acceptance, aiming to improve the text and several details about the methodology and conclusions.
Specific comments:
Please revise the abstract according to the structure of a typical abstract in scientific articles.
Line 2: “contact-less” should be “contactless”
Line 10: “composite one” do you mean “fiber reinforced composites” ? Please revise along the text
Line 14: “A growing trend in engineering is focusing on new methods for structural integrity monitoring and analysis of the mechanical system behaviour, in order to detect defects, preventing malfunctions and failures.” This sentence is not clear, please revise it.
Line 22: “The full-field nature enables the identifying of strain concentrations and damage more accurate. One of the most interesting techniques in this field is the thermoelastic stress analysis (TSA).” TSA is not ready for full-field measurements in real conditions, please rephrase your sentence, considering the limitations of TSA.
Line 66: “The model was created in MATLAB and its fundamentals rely on the finite element method (FEM).” Which model was created in Matlab? Why is it created?
Line 80: “Finally, with this information, and after some data processing” Please detail what means “some data processing”
Line 84: {u} the brackets are not in italic
Line 96: “Since the last two types are computationally expensive, the choice, in this simulation, relies in 3-node or 4-node elements.” This is not completely true, for the same level of accuracy, the 8/9 nodes elements can be less computationally expensive, since that mesh refinement required is much lower.
Line 116: “The jacobian matrix” should be “The Jacobian matrix”
Line 119: Equation 2 requires the brackets. The functions are not in italic (as “det”)
Line 120: Equation (3) is not a real evaluation for anisotropic materials. This is for orthotropic materials. Please revise it along the text. In addition, the reference (15) is a manual of Solidworks, which should not be considered as a scientific reference.
Line 133: Please revise the annotation used in equation (5)
Line 148: Reference [16] is not a real bibliographic reference, please use some compendium or article.
Line 180: Equation 14: please use letters for variables “period” and “number of cycles”
Line 213: “ASTM E 647-08 norm” this is not a norm, but a standard
Line 214: Figure 1 is not real drawing, please review it according international drawing guidelines.
Line 215: “Although this mesh doesn’t possess a structured form, the obtained results should be accurate enough for this purpose, even more due to the small dimensions of the elements near the crack tip area, which is the area of most interest.” How you know that the results are accurate enough? Did you perform a mesh sensitivity analysis? Please present the results.
Line 234: “3.2. SLJ” Please avoid acronyms in section titles.
Line 258: The drawing presented in figure 4 is unclear, please revise it.
Line 264: Poisson’s coefficient (ratio) is in which direction? Please detail it. The same for the Yield strength.
Line 292: “Figure 10. Graphic of stress vs frequency” should be “Plot of stress vs. frequency”
Line 378: “This should be due to the used meshes, and so a more refined mesh around these two points should be used.” Why is this not done in the current work? It should be considered.
Line 390: The current work can be considered for orthotropic materials, however, for anisotropic materials, it seems that it requires a more comprehensive and complex study. Please revise the conclusions addressing these points. It should be also presented the major limitations of TSA technique for isotropic and orthotropic materials.
Author Response
Reply is in the attached pdf file.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript is concerned with the development of a computational method, based on FEA, for simulating the TSA and its application to composite materials. The state of art is not adequately considered. The numerical method requires an experimental validation.
The paper can be published only after major revisions.
- The authors should add a “Nomenclature” with the unit of measure for all the variables reported in the paper.
- Paragraph 1 “Introduction” it is stated: “Thermography techniques are gaining popularity because they are contact-less, non-intrusive, rapidly deployable, applicable to structures under harsh environments and can be performed on-site”. This sentence needs a discussion considering the state of art. The thermography techniques are widely applied also for the fatigue assessment (DOI 10.1016/S0142-1123(99)00088-2, 10.1016/S0167-6636(97)00047-1, 10.1016/j.ijfatigue.2014.12.010, 10.1016/j.ijfatigue.2017.07.025).
- There are several papers in literature about the paper topic. The authors should highlight the difference and novelty of their study respect to these papers.
- The paragraph 2 “Methodology” is a bit long and should be reduced.
- The frequency effect requires a deepest discussion.
- The numerical results, obtained by the computational method, needs an experimental validation. This is mandatory.
Author Response
Reply is in the attached pdf file
Author Response File: Author Response.pdf
Reviewer 3 Report
The present research is focused on creating a finite elements based computation model that simulates Thermoelastic stress analysis technique when applied to anisotropic materials, e.g. composites.
Firstly considering that TSA is a well-established experimental technique, please discuss which could be the advantage of using a FE model to simulate thermoelastic material response? Of course, please include in the text a comment on the novelty of present research.
The papers presents some lacks that will be showed in detail furtherly in present document, so that, in my opinion, it cannot be accepted as it is for the submission unless the following comments have been carefully addressed.
- As TSA is well-known, and relevant new researches have been published, please refer to some new ideas and consider to include in the introduction the some of the following new researches that have been recently published on the topic of TSA:
o Fracture mechanics:
§ Palumbo, D., De Finis, R., Di Carolo, F., Vasco Olmo J., Diaz, F.A., Galietti, U. Influence of Second-Order Effects on Thermoelastic Behaviour in the Proximity of Crack Tips on Titanium Experimental Mechanics, 2021.
o Non-destructive evaluation, Residual Stresses, Damage evaluation
§ De Finis, R., Palumbo, D., Galietti U. Evaluation of damage in composites by using thermoelastic stress analysis: A promising technique to assess the stiffness degradation. Fatigue and Fracture of Engineering Materials and Structures, 2020.
o TSA general modelisation
§ Di Carolo, F., De Finis, R., Palumbo, D., Galietti, U Study of the thermo-elastic stress analysis (TSA) sensitivity in the evaluation of residual stress in non-ferrous metal . 2019 Proceedings of SPIE - The International Society for Optical Engineering 11004,110040O
§ Di Carolo, F., De Finis, R., Palumbo, D., Galietti A thermoelastic stress analysis general model: Study of the influence of biaxial residual stress on aluminium and titanium., U. 2019 Metals 9(6),671
I suggest also to include some pioneer researches:
§ Emery TR, Dulieu-Barton JM. Thermoelastic Stress Analysis of damage mechanisms in composite materials. Composites: Part A.2010; 41:1729–1742
§ Pitarresi G, Found MS, Patterson EA. An investigation of the influence of macroscopic heterogeneity on the thermoelastic response of fibre reinforced plastics. Comp Sci Tech.2005; 65: 269–280
§ Stanley P. Beginnings and early development of thermoelastic stress analysis. Strain. 2008;44(4):285-287
Moreover, from the introduction it is not clear the ultimate goal of the research, please better detail the introduction and specify what is the ultimate goal of the simulation.
- Page 2, Line 70. Section 2. A workflow of the methodology would be effective to understand step-by-step the carried out analyses.
- Page 6. Line 205. A table showing the simulation plan is necessary to understand results and the whole goal of the research.
- Did you validated the numerical model with experiments? This is a great lack in the research.
- Which is the error made in considering different input parameters in the simulations? Are the error significant or not? Please comment on and add in the manuscript more information on how to validate a simulation.
- The same considerations are valid for section 4.2.
As general remark, the simulations are important to design the experiments and to have an idea of what expect from the specific analysis. However, the ultimate goal of a research is the experiment and not the simulation. The simulation must be experimentally validated.
Author Response
Reply is in the attached pdf file
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Please revise the nomenclature: the units of "Convection coefficient" are non-italic, as well as the "Thermal conductivity" - K
The bibliography should be also revised:
Reference 1, author is not "Jr." but "Sharpe Jr"
The number of citations should be removed.
Reference 25 should be revised
Reference 31 should be revised
Author Response
The reply is in the attached pdf file.
Author Response File: Author Response.pdf
Reviewer 2 Report
I am not satisfied with the authors’ reply to some of my comments (n. 2, 4, 5 and 6), so the revised paper can be accepted only after major revisions.
The state of art is not adequately considered.
The numerical method needs an experimental validation.
Comment 2
Paragraph 1 “Introduction” it is stated: “Thermography techniques are gaining popularity because they are contact-less, non-intrusive, rapidly deployable, applicable to structures under harsh environments and can be performed on-site”. This sentence needs a discussion considering the state of art.
The thermography techniques are widely applied also for the fatigue assessment as reported in the following papers:
-La Rosa G & Risitano A. Thermographic methodology for rapid determination of the fatigue limit of materials and mechanical components. Int J Fatigue. 2000;22(1):65-73. DOI: 10.1016/S0142-1123(99)00088-2
-Luong MP. Fatigue limit evaluation of metals using an infrared thermographic technique. Mech Mater. 1998;28(1-4): 155-163. DOI: 10.1016/S0167-6636(97)00047-1
-Wang X et al. Energy-based approach for fatigue life prediction of pure copper. Int J Fatigue. 2017;104:243-250. DOI: 10.1016/j.ijfatigue.2017.07.025.
This advantage of the thermography techniques should be discussed in the Introduction along with the above mentioned papers.
Comment 4
The paragraph 2 “Methodology” is a bit long and should be reduced.
Comment 5
The frequency effect requires a deepest discussion.
Comment 6
The numerical results, obtained by the computational method, needs an experimental validation also considering data taken from literature. This is mandatory.
Author Response
The reply is in the attached pdf file.
Author Response File: Author Response.pdf
Reviewer 3 Report
The paper presents improvements with respect to its initial version.
In my opinion, it is now acceptable for the publication.
Author Response
The reply is in the attached pdf file.
Author Response File: Author Response.pdf
Round 3
Reviewer 2 Report
Authors didn't make a strong effort in order to improve the scientific quality of their paper.
Anyway the revised paper can be accepted.
