Suggestion of Practical Application of Discrete Element Method for Long-Term Wear of Metallic Materials

Round 1

Reviewer 1 Report

In this manuscript, the authors applied the discrete element method (DEM) to analyze the damage behavior in metallic materials subjected to a contact loads with friction. The DEM method used in this numerical investigation helps the authors to predict the motion and contact load of each particle of the material as well as the interaction between these particles in their dynamic collision during the contact.

In reviewer's opinion, the paper can be recommended for publication in Journal of applied science after addressing minor revision considering the following remarks:

- The introductory section needs to be updated, the authors need to analyze some recent references (2020-2022). Research on damage behavior using models such as Lemaitre, Jonson Kook... should be added in the introduction section and compared with the DEM approach.

- At the end of the introductory section it is better if the authors add an introduction of their work.

- Line 181 previous section not chapter.

- The samples were made from a tungsten carbide-cobalt (WC-Co) alloy, but in Figure 4, we notice that this sample is made up of two elements: one part in green and one in blue. Are these two elements from the same material or from two different materials?

- In section 3.1. The contact between the two bodies is not described what is the type of contact model used in the simulation?

- The quality of figure 15 need to be improved

- In Figure 17, it is clear that section 3 is the least damaged section during the loading contact, but it is not well explained why this section is the weakest. The reason need to be specified on the discussions.

- Why is the evolution of the tangential force not of the same order as the magnitude of the wear? Yet, in many references, there is a link between the tangential force and the damage in the mechanical contact. Authors need to specify the reason on the discussions.

- In the conclusion section it is recommended to highlight the novelty of the current research

Author Response

We greatly appreciate the referee’s valuable comments and helpful suggestions. We have done our best to improve the contents of our paper based on your comments.

The referee’s comments were carefully reflected. The revised contents are described below, and the modifications of the manuscript are marked in red and attached separately.

We have attached a separate file to reply to your comments

And the manuscript has been corrected for general English grammar and spelling. All the modifications are reflected in the text and are not marked separately. 
We also attached the certification of the proofreading as a separate file.

Thanks again for your careful review.

Author Response File: Author Response.doc

Reviewer 2 Report

This study represents an interesting contribution to the topic of wear of agricultural equipment. Since in all fields of application wear determines the process efficiency to a large extent, the implementation of a numerical wear prediction into many different modelling theories is of great interest.

In concrete terms, the study follows on previous work and experimental-numerical results of the research group around Katinas et al. The authors aim to examine the numerical wear calculation method in more detail. However, without knowledge of this cited preliminary work, which unfortunately has not been published in open access, the present study is difficult to understand in many places. For example, it remains unclear in this manuscript which agricultural device is involved, how the underlying validation results were generated and the general motivation behind the experimental set-up employed. Furthermore, it is not transparently clear how the present paper differs from Katinas et al. in terms of the numerical methodology. Apparently, the same calculation programme, the same model approaches and identical material parameters are used, all of which have already been described by Katinas et al.. For this reason, it is not clear why, for example, there are significant differences between the simulations of the two studies results shown in Figure 9 and Table 3. Before publication, these issues need to be clearly resolved in the manuscript.

 

Furthermore, there is a need for revision regarding fundamental scientific work in the following points:

-          Please check and revise all figures regarding clarity and font sizes.

-          Literature is not listed in ascending order and needs a revision.

-          General Proof reading is advised as some font layout and spelling issues are found in the text.

-          The Archard law is incorrectly cited. In both the early (1956) and the late (1980) publications of J.F. Archard, the traditional wear model is defined based on the normal load. In fact, there are suggestions in the literature that use shear stress instead, but such a change needs to be more clearly described and motivated.

-          Figures 6, 7 and 8 could be merged in to one Figure for better comprehensibility.

-          Figure 11, 12, 13 and 14 appear very redundant, as at least between section 2, 3 and 4 (figures 12, 13 and 14) hardly any differences are visible. A more reduced and clearer presentation is therefore requested.

-          Figure 15 is missing some explaining annotations eg. wear track on they “x-axis”.

-          Analogously, figures 16, 17 and 18 also appear redundant. Although they are mentioned in the text, they are not substantially addressed in terms of content, so that here again a reduced presentation or a shift to the appendix would make sense.

-          Regarding Chapter 4.3: Why is the normal force compared to the tangential force? What is the relevance for this study?

-          The manuscript lacks a separate discussion chapter. With regard to the fact that the paper currently lacks a clear differentiation from previous work, this chapter is strongly recommended.

-          Since Katinas et al. could already proof, that a computation of wear is possible using the DEM method, the abstract needs a revision to correctly address the content of the manuscript.

Author Response

We greatly appreciate the referee’s valuable comments and helpful suggestions. We have done our best to improve the contents of our paper based on your comments.

The referee’s comments were carefully reflected. The modifications of the manuscript are marked in red and attached separately.

We have attached a separate file to reply to your comments

And the manuscript has been corrected for general English grammar and spelling. All the modifications are reflected in the text and are not marked separately. 
We also attached the certification of the proofreading as a separate file.

Thanks again for your careful review.

Author Response File: Author Response.doc