Wear Behavior of AZ61 Matrix Hybrid Composite Fabricated via Friction Stir Consolidation: A Combined RSM Box–Behnken and Genetic Algorithm Optimization

Round 1

Reviewer 1 Report

The aim of this paper focuses on the understanding of the wear mechanisms, during Friction stir consolidation (FSC) of  metal matrix hy- 22 brid composites (MMHC). For this a Combined RSM Box- 3 Behnken and Genetic Algorithm Optimization approaches have been used.

My comments are :

1°) In the abstract the originality of the work must be clearly identified.

2°) From my point of view, the approaches proposed in the literature for the wear analysis which are based on the experimental design and the statistical methods must be cited and discussed in the introduction. For the moment the introduction is poor and can be improved. For this I recommend the following papers to include in the introduction

a)V Krishnaraj, et al.   Optimization of machining parameters at high speed drilling of carbon fiber reinforced plastic (CFRP) laminates. Composites Part B: Engineering 43 (4), 1791-1799. 2012.

b) R Zitoune, et al.  Tribo-functional design of double cone drill implications in tool wear during drilling of copper mesh/CFRP/woven ply.Wear 302 (1-2), 1560-1567. 2013.

 

3°) In the section, 2: Quality of the figure 1 must be improved. Please include scales in the images. Same comments for other figures (e.g. figure 2 ...)

4°) As the experimental design selected are based on three parameters with three levels for each, why authors does not study of full experimental design. Please justify your choice.

5°) In the figure 8, authors present the SEM image of wear morphology of GA optimized sample. It will be interesting to compare with two other conditions from the experimental design used.

5°) Conclusion must be improved.

 

Author Response

Comments from Reviewers and Responses from Authors

REVIEWER 1 COMMENTS:

Comment 1:  In the abstract the originality of the work must be clearly identified.

Response: Dear reviewer, I want to take a moment to express my sincere appreciation for the time and effort you put into reviewing my manuscript. As per the comment 1, [the originality of the work has been clearly identified and added in the abstract section of line 2-4 as “The originality of this study involves exploration of the fabrication technique (FSC), the selection of materials and the optimization of wear behavior through a systematic investigation of process parameters.”].

Comment 2: From my point of view, the approaches proposed in the literature for the wear analysis which are based on the experimental design and the statistical methods must be cited and discussed in the introduction. For the moment the introduction is poor and can be improved. For this I recommend the following papers to include in the introduction.

1799. a) V Krishnaraj, et al.   Optimization of machining parameters at high speed drilling of carbon fiber reinforced plastic (CFRP) laminates. Composites Part B: Engineering 43 (4), 1791-1799. 2012.
      
      b) R Zitoune, et al.  Tribo-functional design of double cone drill implications in tool wear during drilling of copper mesh/CFRP/woven ply.Wear 302 (1-2), 1560-1567. 2013.

Response: We appreciate the depth and detail of your literature recommendations, as they allowed us to identify specific areas where we could make revisions and improvements. We found this literature as helpful and included in introduction section as: V. Krishnaraj et al. [8] optimized machining parameters for drilling carbon fiber reinforced plastic laminates at high speeds by considering process parameters (spindle speed and feed rate). Moreover, authors implemented analysis of variance (ANOVA) to investigate the percentage contribution of process parameters on the response with confidence level of 95% and they found that Thrust force is more influenced by feed rate. In addition to this, authors developed and confirmed regression model with error percentage of 3.411% to 8.9122% for different responses. Likewise, they used genetic algorithm through MATLAB R2010a and the optimized operating condition predicted by GA was found to be 12,000 rpm at 0.137 mm/rev. R. Zitoune et al. [9] investigated the effect of process parameters (Spindle speed (rpm) 2020 and 2750, Feed rate (mm/rev) 0.05, 0.1, 0.15 and 0.3) on the tool wear during drilling of copper mesh/CFRP/woven ply experimentally and they found that It was discovered that increasing the spindle speed from 2020 rpm to 2750 rpm led to a little decrease in the thrust force. Due to the friction between the tool and CFRP, increasing spindle speed contributes in raising the temperature of machining, which softens the material and reduces thrust force. [Citation has been made on page 2: line 46-54 and Page 3 line 1-7; references are also added bibliography and red colored]

Comment 3: In the section, 2: Quality of the figure 1 must be improved. Please include scales in the images. Same comments for other figures (e.g. figure 2 ...)

Response: Your insight have trully helped me refine my work, and I am gratefull for the opportunity to learn from from your expertise. I have enhanced and replaced the image with a better quality image additionaly scales have been added on the figure 1 and figure 2 [These corrections have been made on page 4 (figure 1) and page 6 (figure 2)].

Comment 4: As the experimental design selected are based on three parameters with three levels for each, why authors does not study of full experimental design. Please justify your choice.

Response: Dear reviewer, I want to thank you for your professional questions. My justifications are described with four points as follows:

1. Cost and time constraint: Conducting a full experimental design can be resource intensive, both in terms of time and cost. Running experiments for all possible combinations would require a substantial investment of resources, including materials, equipment and personnel.
2. Efficiency and optimization: Box-Behnken designs and genetic algorithms aims to optimize the experimental process by reducing the number of experiments required while still providing meaningful results. These methods strategically select a subset of experiments to maximize the amount of information obtained with the fewest experiments possible.
3. Statistical considerations: Statistical analysis plays a crucial role in experimental design. Researchers often use statistical techniques to analyze and experimental data and draw conclusions. Full factorial designs require large number of experiments, leading to a large dataset that may be difficult to analyze and interpret effectively. However, by using designs like Box-Behnken and Genetic Algorithm, researchers can obtain a sufficient amount of information with a smaller amount of experiments, making the data analysis more manageable.
4. Regression Model: The developed regression model can well predict the response of experimental combinations without practically running full experimentation.

Comment 5: In the figure 8, authors present the SEM image of wear morphology of GA optimized sample. It will be interesting to compare with two other conditions from the experimental design used.

Response: I want to thank you again for your suggestions regarding comparison of figure 8 (now it is changed to figure 9 according to the other reviewer we have added one image before figure 8) SEM image with two other conditions. Accordingly, authors agreed cordially to compare the worn out sample of optimum sample which was predicted by RSM versus Genetic Algorithm. Likewise, the comparisons are added as figure 9a and figure 9b while the added discussions are red colored on page 15.

Comment 6: Conclusion must be improved.

Response: I want to thank you again; I have carefully considered each of your comments and have made revisions based on your feedback. The conclusion section has been improved on page 16 with three main conclusion points drawn and modified based on the above comments and suggestions.

 

 

Reviewer 2 Report

Metal matrix composites are increasingly being used in various fields of technology. They are applied in the aerospace, space, military, automotive, and electronics industries. To improve the tribological and mechanical characteristics of aluminum alloys, different reinforcements are added, and corresponding composites are formed. Better  explain the application areas of metal matrix composites - in more detail.

Hybrid composites are obtained when two or more reinforcements are added to the base material. How do the mechanical and tribological characteristics of hybrid composites change compared to the base alloy or material?

At the end of the introduction, provide the main contribution of the paper and highlight how it differs from similar papers in this field. What is the reason for publishing this paper?

Since the reinforcement content is primarily expressed in terms of mass, unify the notation (%wt or %wt. or wt.% or wt%).

Suitable values for load, sliding speed, and sliding distance were chosen during the realization of the tribological tests. Based on what criteria were these values selected? Which real machine system corresponds to these selected input parameter values?

How many different samples were used to test the tribological characteristics of the materials? How many times was the experiment repeated? Show deviations in the obtained values.

Present the metallographic structure of the composite before the tribological tests. What is the distribution of particles? What are the mechanical characteristics of the selected composites?

How was it concluded that delamination is the main wear mechanism? Perform EDS analysis. Was there any material transfer from the pin to the disk?

Verify the experiment using another method (Taguchi design, PSO, ANN...). Please refer to the following papers: [DOI: 10.18485/aeletters.2021.6.2.1], [DOI: 10.1108/ILT-07-2021-0262].

 

Expand the discussion section. Compare the obtained results with other paperss in this or similar areas.

Based on the extended analysis and discussion, expand the concluding remarks.

Author Response

REVIEWER 2 COMMENTS:

Comment 1: Metal matrix composites are increasingly being used in various fields of technology. They are applied in the aerospace, space, military, automotive, and electronics industries. To improve the tribological and mechanical characteristics of aluminum alloys, different reinforcements are added, and corresponding composites are formed. Better  explain the application areas of metal matrix composites - in more detail.

Response: Dear reviewer, we want to thank you for your thorough and constructive feedback. Accordingly, we authors have added the application areas of metal matrix composites in more detail on page 2 line from 39 to 45.

Comment 2: Hybrid composites are obtained when two or more reinforcements are added to the base material. How do the mechanical and tribological characteristics of hybrid composites change compared to the base alloy or material?

Response: Dear reviewer, your questions are greatly appreciated and accordingly answered as follows:

The mechanical and tribological characteristics changes depend on the nature of the hybrid composite and the combination of materials used. Here are some general considerations; for instance when mechanical Characteristics (Strength and Stiffness) are considered, Hybrid composites can potentially exhibit improved strength and stiffness compared to the base alloy. This enhancement is achieved by combining materials with different mechanical properties, such as high-strength particles embedded in a matrix material. The reinforcing material can effectively distribute and bear loads, leading to increased strength and stiffness. Additionally, when tribological Characteristics (wear Resistance) considered, hybrid composites can offer improved wear resistance compared to the base material. The incorporation of wear-resistant materials, such as ceramics (SiC and ZrO₂) or hard particles, can enhance the composite's ability to resist surface degradation and reduce wear rates. Generally, it is important to note that the specific changes in mechanical and tribological characteristics of hybrid composites depend on the chosen materials, their composition, processing methods, and other factors. Detailed analysis and testing are typically required to evaluate and optimize these characteristics for a specific hybrid composite system.

Comment 3: At the end of the introduction, provide the main contribution of the paper and highlight how it differs from similar papers in this field. What is the reason for publishing this paper?

Response: I would like to thank you again for your suggestions, accordingly, corrected as “the wear behavior of magnesium alloy (AZ61) matrix composite materials produced by FSC process, have not been investigated so far. Likewise, there is a lack in the literature when it comes to analyzing the wear and thermal properties of MMHCs fabricated using the FSC process. As a result, the purpose of this study is to fill a knowledge gap by examining the wear and thermal behavior of MMHCs fabricated through FSC process.” [The corrections are made on the last 6 lines of introduction section].

Comment 4: Since the reinforcement content is primarily expressed in terms of mass, unify the notation (%wt or %wt. or wt.% or wt%).

Response: Dear reviewer, your feedbacks and contributions are greatly appreciated. Based on your suggestions the corrections are made uniform to “%wt” on abstract section and on pages 3, 7, 10, 13 and 14.

 

Comment 5: Suitable values for load, sliding speed, and sliding distance were chosen during the realization of the tribological tests. Based on what criteria were these values selected? Which real machine system corresponds to these selected input parameter values?

Response: I would like to express my sincere gratitude for the time and effort you devoted to review my manuscript in detail. The selection of load, sliding speed, and sliding distance for tribological tests is based on several criteria, including:

1. Realistic Operating Conditions: The chosen values should simulate the actual operating conditions of the target machine system as closely as possible. The load, sliding speed, and sliding distance should be representative of the expected forces, velocities, and distances encountered during the machine's normal operation.
2. Safety Considerations: The values should ensure safe testing conditions without risking damage to the test equipment or compromising the safety of the testing personnel. Excessive loads or velocities can lead to equipment failure or hazardous situations.
3. Material Compatibility: The values should be within the operating limits of the materials being tested. They should not exceed the material's maximum load-bearing capacity or cause excessive wear, deformation, or failure.
4. Standardized Testing: In many cases, established standards or protocols for tribological testing provide guidelines for selecting load, sliding speed, and sliding distance values. These standards ensure consistency and comparability of test results across different studies and laboratories.
5. Additionally, deciding the level of each factor was based on a thorough assessment of the literature. Even though the materials investigated for the study were not found in any published works, close level values were chosen.

 

Comment 6: How many different samples were used to test the tribological characteristics of the materials? How many times was the experiment repeated? Show deviations in the obtained values.

Response: Your comments and suggestions were extremely helpful in refining the content and improving the overall quality of the paper. Accordingly, the numbers of samples used during experimentation were 15 and experiments were repeated twice and the average results were taken according to Box-Behnken design. The deviation of each experiment has been added in the table 5 on page 7.

Comment 7: Present the metallographic structure of the composite before the tribological tests. What is the distribution of particles? What are the mechanical characteristics of the selected composites?

Response: Dear reviewer thank you for you fine contribution. We have presented the metallographic structure before the wear test in subtopic 5.7.; as Figure 8 SEM Metallographic Structure of Metal Matrix Hybrid Composite, on page 14, we have showed the particles distribution. Additionally, the mechanical characteristics of MMHCs are well described and investigated in our previous study and we have cited our previous work [37] based on your suggestions.

Comment 8: How was it concluded that delamination is the main wear mechanism? Perform EDS analysis. Was there any material transfer from the pin to the disk?

Response: Dear reviewer, thank you for your insightful question regarding the detection of delamination on worn-out specimens using SEM image analysis. I appreciate your suggestion to conduct an EDS test to complement the analysis. To determine the presence of delamination solely through SEM image analysis, there are several key features and indicators that can be observed and analyzed. Delamination typically manifest as a separation or detachment of layers within a material, which can be visualized using SEM imaging techniques. By carefully examining the SEM images, we can gather valuable information that helps identify delamination. Here are some key observations and analysis methods that can aid in delamination detection using SEM:

1. Morphological changes: delamination often results in distinct morphological changes, such as the formation of voids, cracks and blister like structures. These features can be visually identified in the SEM image and serve as strong indicators of delamination
2. Delamination interfaces often exhibit characteristics patterns such as irregular or rough surfaces as it has been depicted in the figure 9a and 9b, debonding, or interfacial debris and existence of stepped fracture patterns. Careful examination of these interfaces can provide valuable insight into the presence of delamination.

During wear test, the worn out particles are suspended on disc but the weldment of these particles does not take place with disc.

 

Comment 9: Verify the experiment using another method (Taguchi design, PSO, ANN...). Please refer to the following papers: [DOI: 10.18485/aeletters.2021.6.2.1], [DOI: 10.1108/ILT-07-2021-0262].

Response: We appreciate the depth and detail of your literature recommendations, as they allowed us to identify specific areas where we could make revisions and improvements. We found this literature as helpful. A comparative analysis of wear rate optimization studies using RSM and GA, in contrast to studies utilizing Taguchi method and ANN have been made. As per your comment number corrections are made [Citation has been made on page 8 in analysis of variance section and in page 10, as [26] confirmation for normal probability plot,  in page 12 genetic algorithm section and also Added in reference bibliography [26] [33] and red colored.

The second paper has been cited on page 12 and red colored.

Comment 10: Expand the discussion section. Compare the obtained results with other paperss in this or similar areas.

Response: Dear reviewer, thank you for your constructive suggestion again; based on the suggested references, discussions has been made on pages page 8, page 10, and page 12.

Comment 11: Based on the extended analysis and discussion, expand the concluding remarks.

Response: Your insight have trully helped me refine my work, and I am gratefull for the opportunity to learn from from your expertise. According to your suggestions the corrections are made in conclusion section on page 15-16.

Round 2

Reviewer 1 Report

The authors have improved the manuscript following the recommendation of the reviewer. However, before the final acceptance, authors should homogeneous the style of writing of the references list.

Reviewer 2 Report

Accept in present form