Analysis of Dynamic Response Behavior of Crack under Impact Stress Wave

Round 1

Reviewer 1 Report

The problem of investigating shock dynamic loading of materials is as interesting as it is complicated. Difficulties encountered in the process of carrying out experimental research as well as description and analytical or numerical modeling. The authors undoubtedly undertook an ambitious challenge, to declare the creation of numeric models of the dynamic behavior of cracks under impact loading conditions.

However, the peer-reviewed article does not present a number of issues important for understanding the problem. 

1. The abstract used the abbreviation SHPB without explanation;
2. Introduction written very generally, the main goal not clearly stated.
3. Despite declaring cracks in the models in the title of the study, I am dealing with concentrators, not a crack or a crack tip. The plastic zones in the area of the crack tip and the concentrators are absolutely different. Of course, the behavior of the wave will also be different.
4.  The most important objection is that the models do not take into account the behavior of the microstructure in the area of ​​the concentrator. The real material is not homogeneous, and it adsorbs the energy of the wave by modifying the structure and actually only during the first wave. Most of the modifications take place in the volume of the material near the wave source. This issue is analyzed in the works in the area of ​​mesomechanics, in the area of ​​which the author enters by introducing the elementary part of the material for modeling. Chausov at. all (2015) as well as Panin, Meyers and others .
5. The use of compact models of samples for tensile is not fully understood, and whether the stages of initiation and propagation of the crack are taken into account ?
6. The conclusions are also very general and not specific. besides, I don't see any validation of the results and models.
7.  

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Manuscript Number: metals-1465793

Manuscript title: Analysis of Dynamic Response Behavior of Crack under Impact Stress Wave

Journal: Metals

Even though the subject of the manuscript is interesting, the reviewer cannot recommend its publication in the present form. The reviewer suggests major revisions. The main issue is related to the necessity of validating the FE analysis by experimental tests, which should be added to the manuscript.

Nevertheless, other comments should be addressed:

- Please, rephrase the abstract as it is a bit confusing.

- Please, check the manuscript to fix some punctuation mistakes.

- More details about FEA should be added. The authors are asked to define material model, as only elastic properties are defined in table 1 and clarify if the whole stress-strain curve of the material was considered.

- The authors should add details about mesh sensitivity test and element size.

- The independence of strain rate should be supported by literature or experimental data.

- From figure 4 the mesh appears to be asymmetric respect crack tip. This is not good for the symmetry of the results.

 - The authors should describe in details how non-linear load has been defined in FEA.

- At page 8, line 254 the authors write: “Material model of concrete models is adopted as linear elastic homogeneous medium with Rayleigh damping, in order to compensate the effect of microstructure.” Please clarify why the authors talk about concrete as the considered specimens is made of 2A12T4 aluminum alloy.

- Section “3.3.2. Numerical simulation of stress wave propagation in structural impact failure process” lacks of deep analysis.

- Please, clarify how the dimension of plastic zone has been defined.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Thanks for the answers. The article can be published in this form 

Reviewer 2 Report

The manuscript can be accepted