Probing the Impact Energy Release Behavior of Al/Ni-Based Reactive Metals with Experimental and Numerical Methods

Round 1

Reviewer 1 Report

This is a very nice and comprehensive paper focusing on experimental and computational studies of the impact energy release associated with exothermic chemical reactions in Al/Ni based reactive materials. It includes well characterized materials processed using hot-pressing, which are subjected to mechanical testing at various strain rates, and impact testing using a ballistic gun. Pressure sensors are used to monitor the total pressure increase due to reaction, from which the release energy and temperature are calculated using modified JOhn-Cook strength and failure models. A numerical simulation model for chemical reaction associated with impact is also calculated using LS-Dyna code. The results of reaction fraction calculated from the experimental data and model prediction are generally found to be in good correlation. 

Author Response

Dear Reviewer：
      Thank you very much for taking the time to review our manuscript. Of course, there are still many places worthy of improvement and continued research.

The responses are in the Word file.

We will continue to work harder to conduct more in-depth research in the future work.
       If you have any questions or suggestions about the manuscript, please feel free to contact us and we will accept and modify them with humility.
        Thanks again!

Author Response File: Author Response.pdf

Reviewer 2 Report

1. The problem solved numerically should be properly formulated and described including equations, geometry, initial data, and boundary conditions. The boundary conditions appears to differ significantly from the conditions of the experiment. What are the boundary conditions and what is the influence of these conditions on the results of numerical simulation? 

2. Equations (2) and (3) are the same relation. The last of them should be omitted.

3. What is the accuracy of the estimate (8)?

4. Some notations in formulas are not explained.

5.The notations 1 and 2 in Figure 3 are not used. Figure 12 is not clear.‍

Author Response

Dear Reviewer：
      Thank you very much for taking the time to review our manuscript. Of course, there are still many places worthy of improvement and continued research.

The responses are in the Word file.

         We will continue to work harder to conduct more in-depth research in the future work.
       If you have any questions or suggestions about the manuscript, please feel free to contact us and we will accept and modify them with humility.
        Thanks again!

Author Response File: Author Response.pdf

Reviewer 3 Report

The article under consideration, "Probing the impact energy release behavior of Al/Ni-based reactive metals adopting experimental and numerical method" submitted by Ren et al., presents a study of the energy release behaviour of three types of Ni/Al-based reactive material formulations. The formulations were subjected to quasistatic and dynamic mechanical testing in an effort to determine parameters for the well-known Johnson-Cook constitutive model. The energy release behavior was determined through ballistic tests into a test chamber and measurements of the overpressure – a standard approach for energetic materials. This information was utilized in an LS-DYNA model to investigate the link between impact velocity and the fraction of material participating in reaction. Comparison to the experiments revealed general agreement to within 20-30%.

 

Quantifying the energy-release characteristics of reactive materials is an important area of research, and one which is usually addressed at the continuum scale. While the methods themselves are not individually novel, the overall combination of experiments, theory and simulation described in this work is admirable. Additionally, the exploration of subtle compositional variations within a class of demonstrated reactive materials would certainly be of interest to the community.

 

The general readability of the paper is good, save for a few spelling/wording errors which are hopefully captured below. In addition, there are several specific comments which the authors will need to address in their minor revision of this article:

 

1)         There are very few details about the starting material, for example the particle size, shape and nature of both the oxide and metal powder components. These details can be very important to the sensitivity of reactive and energetic materials, and thus need to be stated in order for the present results to be transferrable.

2)         What was the effect of ball-milling on both the structural and chemical properties of the powders? As the previous comment, this processing approach can have a direct and profound influence on the sensitivity of the system, pushing reaction thresholds to lower temperature, for example. Further to this, the powders were heated to 400 degrees C – was this sufficient for any of the material to react?

3)         Figure 1 – the scale bars are nearly impossible to read. Suggest cropping the instrument scale bars and adding a larger annotation.

4)         What was the process for determining the yield stress in the quasistatic data? The yield stresses are very similar, and given the data I doubt two different researchers would arrive at the same values. It would be worth stating what method was used.

5)         The parameters for equations 1-3 are not defined. While these are very familiar equations, the uninitiated reader should be able to read/understand the meaning of the equations without referring to a separate text.

6)         Line 152 – I believe the authors meant to refer to Figure 3, not 8.

7)         Line 154 – Do the authors mean “plateau”, rather than “platform”?

8)         Line 156 – “is so good” is very qualitative. Suggest substantiating this.

9)         Line 157 – “No damage occurred…” – how is this known? Clearly there is macroscopic relaxation, but what about at the mesoscale? The authors may be assuming that all inelastic deformation is through Al or Ni plasticity, but it would be good to confirm this.

10)       Figure 4 b and c are identical! Also, the x-label is mislabeled “Ture Strain”, not “True Strain”.

11)       Table 2 – it might be worth also listing the failure strain for each formulation and strain-rate.

12)       Line 166 – Do the authors mean strain “rate” rather than “ratio”?

13)       Have the authors investigated what yield strength would be predicted for the various formulations using the Rule of Mixtures? How would these compare with the present results?

14)       Line 187 – The argument here about the Johnson-Cook temperature is confusing. As presently written, it seems the authors are struggling with the temperature term T being the current temperature in the body/element, rather than room temperature. Of course, this is simply an empirically-determined multiplicative modifier which attempts to account for the reduction in strength at elevated temperatures. Suggest rewording.

15)       Table 3 – The authors have conducted mechanical tests at 4 strain-rates, but all at room temperature. How was the thermal softening exponent determined in this case? Further to this, there is no discussion of how the J-C parameters were fitted. This must be explained.

16)       Not all parameters in Equation 8 are defined. Some are elsewhere in the text, but the reader shouldn’t need to search for them.

17)       Equation 9 – Do the authors take into account the energy lost due to perforating the thin plate of the test chamber? This will be manifest as a reduction in the impact velocity onto the anvil, damage in the RM material, and damage/heating of the thin plate.

18)       Lines 218-220 – These reactions should be shown in a chemical equation.

19)       Line 283 – From this description, it appears that the extent of reaction is determined from the shock temperature. Does the reaction in turn influence the state variables of the material?

20)       Figure 9 – Suggesting retaining the same colors as the previous plot, to aid direct comparison.

21)       Lines 328,329 – The authors switch the abbreviation, ANM vs AMN.

22)       Line 339 – “impace” should be “impact”.

23)       Line 356 – “imposable” should be “impossible”.

24)       Figure 13 – Given these profiles, is this a sustained chemical reaction, or one which is quenched?

Author Response

Dear Reviewer：
      Thank you very much for taking the time to review our manuscript. Of course, there are still many places worthy of improvement and continued research.

The responses are in the Word file.

         We will continue to work harder to conduct more in-depth research in the future work.
         If you have any questions or suggestions about the manuscript, please feel free to contact us and we will accept and modify them with humility.
        Thanks again!

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors adequately responded previous comments. The work is at the adequate technical level. The paper reports new interesting results. Hence, I recommend the paper for acceptance.

Minor editing of english language is still required. For example, 117    saise -> raise,  202  their plasticity is was so good ->  their plasticity was so good, 253 -  where is the end of the sentence? and so on.

Author Response

Dear Reviewer:

Thank you for taking time to take a second review of our manuscript. Due to our negligence, there were some grammar and spelling errors in the manuscript. According to your suggestions and reminders, we checked the content of the manuscript again carefully and modified these errors.

Of course, there are still many places worthy of improvement and continued research. We will continue to work harder to conduct more in-depth research in the future work. If you have any questions or suggestions about the manuscript, please feel free to contact us and we will accept and modify them with humility.

Thanks again!