The Modelling of Rock Fragmentation Mechanisms by Carbide Buttons Using the 3D Discrete Element Method
Round 1
Reviewer 1 Report
The manuscript entitled " The Modelling of Rock Fragmentation Mechanisma by Carbide Buttons Using 3D Discrete Element Method" investigated the rock breaking mechanism and cutting performance of five widely used carbide buttons. Prior to the publication there are some technical suggestions:
Q1: Relevant researches of DEM and AE technologies should be added to the Introduction. relevant study suggests to cited, as follow:
Evaluation of coarse aggregate movement and contact unbalanced force during asphalt mixture compaction process based on discrete element method, Construction and Building Materials. 328 (2022) 127004.
Monte Carlo simulations of deformation behaviour of unbound granular materials based on a real aggregate library, International Journal of Pavement Engineering. 24 (2023) 2165650
Effect of loading rate on failure characteristics of asphalt mixtures using acoustic emission technique, Construction and Building Materials. 364 (2023) 129835
Q2: Part 3.2 Validation is the comparison of single test results. Please explain the general conclusions of the DEM model.
Q3: Part 4.1 Force-penetration depth curve and AE events：How to eliminate the influence of machine noise on acoustic emission test results？
Q4：Consult the journal's reference style for the exact appearance of these elements, and use of punctuation and capitalization.
Q5：The conclusion part should be more refined to make the findings and contributions of the paper clearer. Furthermore, please note the difference between the conclusions and abstract.
Author Response
Dear reviewer1:
We would like to express our gratitude to you for the time and efforts in our manuscript. Your comments make this manuscript more academic. We have carefully revised the manuscript.
All revisions to the manuscript have been marked up using the “Track Changes”.
We look forward to furthering information about the manuscript.
Yours sincerely
Xiaoxiong Zhou
May 12, 2023
Author Response File: 
Author Response.docx
Reviewer 2 Report
The paper presents numerical and experimental investigation of rock fragmentation mechanism by carbide buttons commonly used in hard rock drilling. The discrete element method was used in numerical modelling and simulations. Indentation of rocks with buttons of five different shapes was simulated. Cutting performance of different buttons was assessed in terms of the penetration index, the crack propagation, the specific energy and energy dissipation distribution. Numerical results were compared with the results of laboratory tests.
The paper contains interesting and original results worth publishing, which are worth publishing, however, the paper has some flaws indicated in the comments below.
Critical comments:
1. The paper contains not precise and untrue statements, for instance:
Page 2: “FEM is difficult to describe rock anisotropy”. My comment: of course, modelling of rock anisotropy is not easy, however the FEM has all necessary capabilities to model an anisotropic material; the possibilities of the FEM in modelling anisotropy are not worse than those of the DEM. Modelling of fractures is another issue than modelling of anisotropy. The cited statement is not correct grammatically.
Page 3: “In the explicit time algorithm, the step time is set very small so that the velocity and acceleration of a particle can be assumed to be constant within a time step, allowing the calculation of the displacement of each particle”. The comment: This statement is not true. First of all the limitation is due to the stability limit, which imposes the limit on the time step length. The velocity is not assumed constant. If the acceleration is assumed constant, then the velocity changes linearly.
2. Page 5: “For a quasi-static problem, a local damping factor of 0.7 was used”. The damping factor has not been defined.
3. Language correction is necessary
The paper can be considered for publication if revision is made addressing the flaws indicated in the critical comments above.
Language correction is necessary
Author Response
Dear reviewer 2:
We would like to express our gratitude to you for the time and efforts in our manuscript. Your comments make this manuscript more academic. We have carefully revised the manuscript.
All revisions to the manuscript have been marked up using the “Track Changes”.
We look forward to furthering information about the manuscript.
Yours sincerely
Xiaoxiong Zhou
May 12, 2023
Author Response File: Author Response.docx
