Research on Identification and Application of Joint Surface Characteristic Parameters

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General Assessment:
The submitted manuscript addresses a significant and timely topic concerning the analysis of the influence of stationary joint surfaces on the dynamic characteristics of machine tools. The paper contributes valuable input to the development of methods for identifying characteristic joint parameters, such as stiffness and damping, and highlights their significant impact on the dynamic behavior of the entire system. The incorporation of micro-asperity interactions into the 3D finite element (FE) model, along with direct model verification using surface fractal parameters, constitutes an original and well-justified research contribution.

Strengths of the Manuscript:

• The authors tackle the complex problem of accurately identifying the properties of joint surfaces, which is of key importance in designing high-precision and high-stiffness machine tools.
• The extension of the classical FE model to include deformations resulting from micro-irregularities is well-grounded and thoroughly implemented.
• The method of determining fractal parameters based on the structural function as a basis for model verification is innovative.
• The model is correctly validated using the GP300 machine tool as a case study.
• The paper is based on a comprehensive review of the literature – the authors correctly cite numerous recent scientific articles.

Comments and Recommendations for the Manuscript:

1. Editorial and Linguistic Aspects:

• The term “work” should be avoided when referring to a scientific publication – recommended alternatives include manuscript, paper, article, study, or scientific article.
• The abstract should be restructured. The current version is overly detailed and includes method descriptions and results. The abstract should consist of no more than 5–6 sentences that introduce the topic, state the aim of the study, and outline its potential significance – without methodological or result-specific details.
• The manuscript lacks a list of symbols and nomenclature. It is recommended to include a complete table of symbols, abbreviations, and physical units – preferably as a separate section at the end of the manuscript.
• A consistent convention for expressing physical units should be applied throughout the manuscript – square brackets are recommended (e.g., [mm], [Hz]) on graph axes, in tables, and figure captions.

2. Graphic and Illustrative Aspects:

• Some charts and figures are not vector-quality. It is recommended to replace Excel-generated plots with vector graphics – for example, using software such as Grapher.
• Figures should use uniform font types, axis label sizes, styles, and colors. Introducing standardized formatting rules will improve the graphical clarity of the work.
• Figure 6 requires correction – it is unclear which equation (among those marked as (12)) corresponds to which curve. The figure caption should be expanded and the coefficient of determination R² should be included.

3. Numerical Modeling (FEM):

• The FEM model description lacks key information: What material model was used (include the stress-strain curve)? What types of finite elements were applied – their type, number of nodes (e.g., 8, 20, 27), number of integration points, shape functions, formulation type, and justification of their selection? What convergence criteria were adopted, and how was computational accuracy evaluated? The element size should be related to the geometry of the analyzed component.
• A paragraph discussing the achieved solution convergence should be added – FEM results are approximations and depend on many factors, the influence of which is worth discussing.
• All FEM result visualizations should clearly indicate what is being presented and in what units.

4. Final Conclusions:

• The current conclusions partially repeat the abstract. They should be reformulated and expanded.

It is recommended to:

• Indicate potential applications of the research results in real engineering systems.
• Propose directions for future research – e.g., in the field of dynamic identification considering operational loads, environmental conditions, or joint wear.
• Address the limitations of the study – e.g., assumed model simplifications or material assumptions.

Summary:
The manuscript presents a significant scientific contribution and introduces an innovative approach to modeling joint surface properties in the context of the dynamic characteristics of machine tools. The quality of execution, logical structure, and scope of the literature are of a high standard. Nevertheless, to improve clarity, coherence, and technical precision, minor but numerous editorial, graphical, and substantive corrections are required.

Final Recommendation: Minor Revision – after addressing the above comments, the manuscript will be suitable for publication.

Author Response

General Assessment:
The submitted manuscript addresses a significant and timely topic concerning the analysis of the influence of stationary joint surfaces on the dynamic characteristics of machine tools. The paper contributes valuable input to the development of methods for identifying characteristic joint parameters, such as stiffness and damping, and highlights their significant impact on the dynamic behavior of the entire system. The incorporation of micro-asperity interactions into the 3D finite element (FE) model, along with direct model verification using surface fractal parameters, constitutes an original and well-justified research contribution.

Strengths of the Manuscript:

• The authors tackle the complex problem of accurately identifying the properties of joint surfaces, which is of key importance in designing high-precision and high-stiffness machine tools.
• The extension of the classical FE model to include deformations resulting from micro-irregularities is well-grounded and thoroughly implemented.
• The method of determining fractal parameters based on the structural function as a basis for model verification is innovative.
• The model is correctly validated using the GP300 machine tool as a case study.
• The paper is based on a comprehensive review of the literature – the authors correctly cite numerous recent scientific articles.

Comments and Recommendations for the Manuscript:

1. Editorial and Linguistic Aspects:

• The term “work”should be avoided when referring to a scientific publication – recommended alternatives include manuscript, paper, article, study, or scientific article.

Response: We have made modifications according to reviewer’s comment.

 

• The abstract should be restructured. The current version is overly detailed and includes method descriptions and results. The abstract should consist of no more than 5–6 sentences that introduce the topic, state the aim of the study, and outline its potential significance – without methodological or result-specific details.

Response: We have streamlined the abstract according to reviewer’s comment.

 

• The manuscript lacks a list of symbols and nomenclature. It is recommended to include a complete table of symbols, abbreviations, and physical units – preferably as a separate section at the end of the manuscript.

Response: We have added a nomenclature at end of the paper.

•  
• A consistent convention for expressing physical units should be applied throughout the manuscript – square brackets are recommended (e.g., [mm], [Hz]) on graph axes, in tables, and figure captions.

Response: The expression convention of physical units in the paper is implemented in accordance with the requirements of the journal.

 

1. Graphic and Illustrative Aspects:

• Some charts and figures are not vector-quality. It is recommended to replace Excel-generated plots with vector graphics – for example, using software such as Grapher.

Response: We have comprehensively improved the image quality in the paper according to reviewer’s comment.

 

• Figures should use uniform font types, axis label sizes, styles, and colors. Introducing standardized formatting rules will improve the graphical clarity of the work.

Response: We have made modifications according to reviewer’s comment.

•  
• Figure 6 requires correction – it is unclear which equation (among those marked as (12)) corresponds to which curve. The figure caption should be expanded and the coefficient of determination R² should be included.

Response: We have added equations corresponding to each fitting curve in the modified picture.

 

1. Numerical Modeling (FEM):

• The FEM model description lacks key information: What material model was used (include the stress-strain curve)? What types of finite elements were applied – their type, number of nodes (e.g., 8, 20, 27), number of integration points, shape functions, formulation type, and justification of their selection? What convergence criteria were adopted, and how was computational accuracy evaluated? The element size should be related to the geometry of the analyzed component.

Response: We have added information on the material model, convergence criteria, and accuracy evaluation basis of the simulation model in the paper as requested by reviewer.

• A paragraph discussing the achieved solution convergence should be added – FEM results are approximations and depend on many factors, the influence of which is worth discussing.

Response: We discussed the factors affecting the accuracy of finite element model simulation in the paper as requested by reviewer.

•  
• All FEM result visualizations should clearly indicate what is being presented and in what units.

Response: The modal shape diagram (Fig. 11 in revised manuscript) is a normalized dimensionless result without units.

 

1. Final Conclusions:

• The current conclusions partially repeat the abstract. They should be reformulated and expanded.

It is recommended to:

• Indicate potential applications of the research results in real engineering systems.
• Propose directions for future research – e.g., in the field of dynamic identification considering operational loads, environmental conditions, or joint wear.
• Address the limitations of the study – e.g., assumed model simplifications or material assumptions.

Response: We have revised the conclusion section of the paper according to reviewer’s comment.

 

Summary:
The manuscript presents a significant scientific contribution and introduces an innovative approach to modeling joint surface properties in the context of the dynamic characteristics of machine tools. The quality of execution, logical structure, and scope of the literature are of a high standard. Nevertheless, to improve clarity, coherence, and technical precision, minor but numerous editorial, graphical, and substantive corrections are required.

Final Recommendation: Minor Revision – after addressing the above comments, the manuscript will be suitable for publication.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript tackles a clear research question, but in its present form it does not meet Applied Sciences publication standards. Substantive revisions to both content and presentation are required. Please consult the annotated PDF for detailed, line level suggestions to guide the revisions.

 

1 - I recommend that the authors revise the title to be more concise and memorable, highlighting the study’s focus, approach, and key implications. A sharper title will improve discoverability and alignment with the manuscript’s content.

 

 

2 - The abstract would benefit from a clearer emphasis on practical applications and the broader implications of the work. Please add one to two sentences that specify who can use the results (e.g., practitioners, policymakers, researchers), how the findings can be applied in real settings, and what impact is expected. Where possible, include a concise quantitative outcome or concrete example to anchor these claims. This will make the contribution and relevance of the study immediately evident to readers.

 

 

3 - In the abstract, you may use “3D” rather than spelling out “three-dimensional.” The abbreviation is standard and widely understood in all the scientific fields.

 

4 - Several of the listed keywords read like full phrases rather than concise terms. Please streamline them into shorter, high‑impact keywords, since effective indexing and search visibility in major academic databases depend on clear, focused keyword choices.

 

5 - The introduction motivates the study by relating joint surface stiffness and damping to machine tool dynamics and by arguing that conventional models bond components or approximate interfaces with spring damper elements, which can yield gaps between simulation and practice.

 It would benefit from a sharper statement of the specific gap relative to existing KE based formulations and prior attempts at direct validation, together with a concise claim of what is new in the present model beyond extending to three dimensional fractal parameters. The narrative should define all acronyms at first use, particularly Computer Numerical Control and KE, and should justify broad scope shifts from wafer thinning grinders to general machine tools. Clear research questions or hypotheses and the measurable outcomes expected later in the paper would help align the introduction with the methods and results and would make the contribution easier to assess.

 

 

6 - At first mention, please spell out the acronym: “Computer Numerical Control (CNC) tools.” After introducing it, you can use “CNC tools” consistently throughout the manuscript.

 

7 - in the introduction, from row 39 to row 41, where authors state "[...] However, in conventional machine tool design and analysis models, components are often either rigidly bonded together or connected via spring damper elements based on empirical assumptions [...]", the sentence lack of a citation. To better contxtualize the concept of machine design and artefacts design in the recent literature scenario, the authors shoud cite here the following work dealing exacly with the scientific concept of complexity of artefacts and its design (sensu Simon):

-Tomassi, A., Falegnami, A. and Romano, E., 2025. Unveiling simplexity: A new paradigm for understanding complex adaptive systems and driving technological innovation. The Innovation. DOI: 10.1016/j.xinn.2025.100954

 

 

8 - "2. Refinement of the Joint Surface Characteristic Parameter Model" paragraph: Section 2 is promising but needs tighter clarity and rigor. Specify upfront whether the 3D KE extension explicitly couples asperity and substrate deformation, and list modeling assumptions and notation consistently. Expand a few key derivation steps and include a quick dimensional check to validate the modified stiffness relations. A brief sensitivity note on D, G, and real contact area would better link the model to later validation.

 

9 - "3. Direct Validation Methodology for Joint Surface Characteristic Parameter Models" paragraph: Section 3 would benefit from sharper methodological detail. Specify sample preparation, surface measurement instrumentation and resolution, loading protocol, and boundary conditions to ensure repeatability. Report uncertainty and statistical treatment of replicates, and compare against baseline models using clear metrics such as RMSE or MAE with confidence intervals. Clarify how parameters are estimated from data and whether any cross validation or independent test set is used.

 

10 - I advise authors to enlarge all figures in the article as much as possible.

 

11 - The current conclusion largely reiterates the study’s content. It would be stronger if it highlighted concrete applications and the broader significance of the findings for practice and research, making clear how the proposed approach can be used in real settings. This section is also the place to distill the main takeaways and explicitly state how the results answer the initial research questions. A brief, candid discussion of the study’s limitations and a forward-looking outline of next steps and open problems would sharpen the message and increase the manuscript’s overall impact and clarity.

Comments for author File: Comments.pdf

Author Response

The manuscript tackles a clear research question, but in its present form it does not meet Applied Sciences publication standards. Substantive revisions to both content and presentation are required. Please consult the annotated PDF for detailed, line level suggestions to guide the revisions.

 1 - I recommend that the authors revise the title to be more concise and memorable, highlighting the study’s focus, approach, and key implications. A sharper title will improve discoverability and alignment with the manuscript’s content.

Response: We have revised the title of the paper according to reviewer’s comment.

 

 2 - The abstract would benefit from a clearer emphasis on practical applications and the broader implications of the work. Please add one to two sentences that specify who can use the results (e.g., practitioners, policymakers, researchers), how the findings can be applied in real settings, and what impact is expected. Where possible, include a concise quantitative outcome or concrete example to anchor these claims. This will make the contribution and relevance of the study immediately evident to readers.

Response: We have revised the abstract of the paper according to reviewer’s comment.

 

3 - In the abstract, you may use “3D” rather than spelling out “three-dimensional.” The abbreviation is standard and widely understood in all the scientific fields.

      Response: We have made modifications according to reviewer’s comment.

 

4 - Several of the listed keywords read like full phrases rather than concise terms. Please streamline them into shorter, high‑impact keywords, since effective indexing and search visibility in major academic databases depend on clear, focused keyword choices.

Response: We have revised the keywords of the paper according to reviewer’s comment.

 

5 - The introduction motivates the study by relating joint surface stiffness and damping to machine tool dynamics and by arguing that conventional models bond components or approximate interfaces with spring damper elements, which can yield gaps between simulation and practice.

 It would benefit from a sharper statement of the specific gap relative to existing KE based formulations and prior attempts at direct validation, together with a concise claim of what is new in the present model beyond extending to three dimensional fractal parameters. The narrative should define all acronyms at first use, particularly Computer Numerical Control and KE, and should justify broad scope shifts from wafer thinning grinders to general machine tools. Clear research questions or hypotheses and the measurable outcomes expected later in the paper would help align the introduction with the methods and results and would make the contribution easier to assess.

      Response: We have made modifications according to reviewer’s comment.

 

6 - At first mention, please spell out the acronym: “Computer Numerical Control (CNC) tools.” After introducing it, you can use “CNC tools” consistently throughout the manuscript.

      Response: We have made modifications according to reviewer’s comment.

 

7 - in the introduction, from row 39 to row 41, where authors state "[...] However, in conventional machine tool design and analysis models, components are often either rigidly bonded together or connected via spring damper elements based on empirical assumptions [...]", the sentence lack of a citation. To better contxtualize the concept of machine design and artefacts design in the recent literature scenario, the authors shoud cite here the following work dealing exacly with the scientific concept of complexity of artefacts and its design (sensu Simon):

-Tomassi, A., Falegnami, A. and Romano, E., 2025. Unveiling simplexity: A new paradigm for understanding complex adaptive systems and driving technological innovation. The Innovation. DOI: 10.1016/j.xinn.2025.100954

Response: We have added appropriate literature citations in accordance with reviewer’s comment at this location.

 

8 - "2. Refinement of the Joint Surface Characteristic Parameter Model" paragraph: Section 2 is promising but needs tighter clarity and rigor. Specify upfront whether the 3D KE extension explicitly couples asperity and substrate deformation, and list modeling assumptions and notation consistently. Expand a few key derivation steps and include a quick dimensional check to validate the modified stiffness relations. A brief sensitivity note on D, G, and real contact area would better link the model to later validation.

Response: This paper is a further study based on reference [18], therefore some repetitive derivations in the modeling process have been omitted. According to reviewer’s comment, some details in the derivation process of this article have been added to facilitate readers' better understanding.

 

9 - "3. Direct Validation Methodology for Joint Surface Characteristic Parameter Models" paragraph: Section 3 would benefit from sharper methodological detail. Specify sample preparation, surface measurement instrumentation and resolution, loading protocol, and boundary conditions to ensure repeatability. Report uncertainty and statistical treatment of replicates, and compare against baseline models using clear metrics such as RMSE or MAE with confidence intervals. Clarify how parameters are estimated from data and whether any cross validation or independent test set is used.

Response: We have added information on the instrument model and key indicators used for measurement in the experimental section. In terms of model validation, the paper compared the theoretical and experimental results under different loads to demonstrate the robustness of the model and validation method. For contour measurement, laser microscopes themselves have ultra-high measurement accuracy and repeatability.

 

10 - I advise authors to enlarge all figures in the article as much as possible.

 Response: We have made modifications according to reviewer’s comment.

 

11 - The current conclusion largely reiterates the study’s content. It would be stronger if it highlighted concrete applications and the broader significance of the findings for practice and research, making clear how the proposed approach can be used in real settings. This section is also the place to distill the main takeaways and explicitly state how the results answer the initial research questions. A brief, candid discussion of the study’s limitations and a forward-looking outline of next steps and open problems would sharpen the message and increase the manuscript’s overall impact and clarity.

Response: We have revised the conclusion section of the paper according to reviewer’s comment.

Reviewer 3 Report

Comments and Suggestions for Authors

In this paper, the authors refine the joint surface characteristic parameter model by incorporating substrate displacement induced by asperity interactions. The article presents the research logically and coherently. Below are some points to ensure the model is better presented and more easily understood by readers.

- The research objective of the abstract and introduction should be fully aligned and presented clearly.

- The introductory text needs improvement. What were the motivations that led to the development and proposal of this model? This needs to be clearly explained.

- What are the contributions of the article? This needs to be made clear in the introduction.

- Before going into detailed explanations of the model, I suggest including a flowchart explaining the steps for applying the proposed model.

- The equations presented in section 2 need to be better explained, demonstrating a more specific flow of the model.

- The practical implications of the model should be included, discussing them and comparing them with other similar previous works in the literature.

- The limitations of the research should be explained in the conclusion, as should prospects for future research.

Author Response

In this paper, the authors refine the joint surface characteristic parameter model by incorporating substrate displacement induced by asperity interactions. The article presents the research logically and coherently. Below are some points to ensure the model is better presented and more easily understood by readers.

- The research objective of the abstract and introduction should be fully aligned and presented clearly.

Response: We have made modifications according to reviewer’s comment.

 

- The introductory text needs improvement. What were the motivations that led to the development and proposal of this model? This needs to be clearly explained.

Response: We emphasized the necessity and innovation of our work in the last paragraph of the introduction.

 

- What are the contributions of the article? This needs to be made clear in the introduction.

Response: There are two pioneering points in the paper. Firstly, the theoretical modeling considers the deformation of the bonding surface substrate caused by the interaction of micro convex bodies. Secondly, a direct verification method for the theoretical model is proposed, which improves the reliability of the verification. We emphasized the necessity and innovation of our work in the last paragraph of the introduction.

 

- Before going into detailed explanations of the model, I suggest including a flowchart explaining the steps for applying the proposed model.

Response: We added a flowchart explaining the steps for applying the proposed model according to reviewer’s comment.

 

- The equations presented in section 2 need to be better explained, demonstrating a more specific flow of the model.

Response: According to reviewer’s comment, some details in the derivation process in section 2 have been added to facilitate readers' better understanding.

 

- The practical implications of the model should be included, discussing them and comparing them with other similar previous works in the literature.

Response: The paper compared the accuracy of three models: the classic KE model, the 3D KE model and the proposed model.

 

- The limitations of the research should be explained in the conclusion, as should prospects for future research.

Response: We have revised the conclusion section of the paper according to reviewer’s comment.

 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

 

I am pleased to inform you that I have completed my review of the revised manuscript. It is evident that the changes made in response to the reviewers' comments have significantly enhanced the clarity and depth of your paper. The efforts you have put into addressing the concerns and suggestions have not only improved the manuscript but have also augmented its contribution to the field.

 

In light of the substantial improvements made, I believe that the manuscript is now well-prepared for publication. The revisions have effectively strengthened the arguments, enriched the data presentation, and refined the overall narrative, thereby solidifying its scholarly value.

 

Thank you for your diligence and commitment to enhancing your work. I look forward to seeing your research published and contributing to ongoing discussions in your area of expertise.

 

Best regards

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have complied with this reviewer's suggestions. The article can be accepted.