A Novel Damage Model to Predict Ductile Fracture Behavior for Anisotropic Sheet Metal
Round 1
Reviewer 1 Report
please, see attached file
Comments for author File: 
Comments.pdf
Author Response
1. In my opinion every figure caption (footer) must be in the same page as the figure in question. This are not the case of Figs. 10 and 23. Moreover there are too many pages with an excessive white space (pages 2, 4, 7, 8, 9, 12, 15, 16, 18 and 19). Fix these two items, a
good work with a good appearance: twice good.
Response: Thank the reviewer for the worthy comment, every figure caption has been put in the same page as the figure in question. The excessive white space (pages 2, 4, 7, 8, 9, 12, 15, 16, 18 and 19) has been removed.
2. Take care with the format of the text (size and space between lines), there are discrepancies
in page 5 (lines 133 to 138) with relation to the rest of the document. The same occurs in lines 184 to 189 and in lines 221 to 223. I suggest making a complete review of this point. I believe that in many cases there are more than one space between words (I suggest a deep review of this point too; sorry if I am wrong).
Response: Sorry, the size and space between lines are different in some text with symbols which is edited with formula editor. Based on the suggestions of reviewer, I have reviewed whole manuscript to correct these discrepancies.
3. Avoid putting the Subsections just in the last line of a page. This is the case of line 285 and
line 321 (subsections 3.2 and 3.3 respectively).
Response: Yes, I have modified the locations of Subsections.
4. According with Metals template, equations should be in the center of the line.
Response: I have put all equations in the center of the line based on the suggestions of reviewer.
5. Line 14: I suppose that authors want to write “approach, and” instead of “approach. And”.
Sorry if not. The same in line 18 for “… the fracture displacements between experiment and simulation”, I think that “… the fracture displacements between experiments and simulations” is better.
Response: Thank the reviewer for the careful review, I have revised these sentences.
6. The references [1, 2], indicated in lines 399 and 402, are not cited in the text
Response: Sorry, the references [1,2] should be removed. I have modified the reference number.
7. Line 43: in the text a reference [8] is cited as Chen et al., but reference [8] has only two
authors (as indicated in line 414).
Response: Thanks, “Chen et al.” has been corrected as “Chen and Dong”.
8. There is not concordance between the reference [13] cited in line 52 and the reference’s
details in line 425. I believe that the problem is in this last line.
Response: The authors in reference [Modified Mohr-Coulomb fracture model for anisotropic sheet materials under limited triaxial stress conditions] are disorder, I have corrected the authors.
9. Lines 62, 63, 66 and others: In my opinion there is a great difference between Finite Element (with many meanings) and Finite Element Method (with a more particular meaning). My suggestion is to use the acronym FEM instead of FE (like in line 243).
Response: Yes, I have revised these words based on the suggestions of reviewer.
10. Line 77: I suggest to change the expression “constant crossed velocity” by “constant cross
head velocity”; both are different terms, but the tension test is carry out thanks to the cross head movement of the engine.
Response: The expression “constant crossed velocity” has been changed as “constant cross
head velocity”.
11. Line 77: I think that the acronym DIC is related to the Digital Correlation Image technique
instead of Digital Correction Image (sorry if I am wrong).
Response: Thank the reviewer for the careful review, DIC is related to Digital Image Correlation, this error has been corrected.
12. Line 103: the term, or stress, si is not defined in the text.
Response: The term =0 represents principal stress , which has been corrected.
13. Line 163: the phrase “Since the r-values in different directions are different” has not sense
in this way.
Response: This sentence has been removed to avoid misunderstand.
14. Line 186: “Fig. 5(a)-(c)” instead of “Fig. 4(a)-(c)”.
Response: The error of caption has been corrected.
15. Lines 188-189: is difficult to understand the meaning of the phrase with since and hence
so close.
Response: What I want to express is that the stress triaxiality and Lode parameter are not 1/3 and -1 at fracture under uniaxial tension state because of necking on tension process. The sentence has been revised.
16. Line 194: I suggest to change “…directions. Because…” by “…directions, because…”.
Response: This sentence has been corrected based on the suggestion of the reviewer.
17. Figs. 9, 10, 11, 12, 13 and 15: what is the meaning of PEEQ? I can not find this term in
the text.
Response: PEEQ represents equivalent plastic strain, which has been added in the captions of Figs. 9, 10, 11, 12, 13 and 15.
18. Fig. 23: the annotations in each fractographic image are not very clear (even on screen), maybe putting a dark background color and a white color in the letters enhance the readability.
Response: The annotations in each fractographic image has been modified based on the suggestions of the reviewer.
19. Line 380: I suggest to improve the wording of “The nearer of fracture location in the center
is the less of stress triaxiality is”.
Response: The sentence has been corrected as “With the increase of stress triaxiality, the fracture location transfers from center to the root of notch.”
20. Fig. 15: with relation to the graph of Fig. 15 I have a different interpretation of the results
included in such graph (and also with relation to the previous graphs of Figs. 9 to 14). The authors write “…and the results show that simulation is in good agreement with the experiment”, in my opinion this is not true. I can see a good agreement in 5 cases [specimens R25(45º, 90º), PLT-R4(45º), PLT-R8(45º) and PLT-R12(45º)], I have doubts with the specimen/sample R4.5(45º), and, finally, I believe that the remaining 12 specimens, or samples, does not show such good agreement. For the case of these 12 specimens is possible to observe differences of ±20% (and more) with relation to the prediction accuracy of 100% or 1.00 in the graph; in my opinion this variation of ±20% is far from “good agreement”.
Response: Yes, I agree with the opinion of the reviewer, I have revised the sentence “…and the results show that simulation is in good agreement with the experiment”, which could be seen in the revised manuscript.
21. One last thing (a tribute to Steve Jobs): how many specimens for each sample was used in
the tension test experiments?
Response: Three repeated specimens have been carried out for every experiment.
Author Response File: Author Response.pdf
Reviewer 2 Report
In the reviewers opinion the paper requires changes:
The English language needs to be improved: too many spelling or tense mistakes are located in the text like:
1 page line 20 "directions have lager differences" or page 2 line 70 "aluminium alloy plate were"
While dealing with sheet materials it would be very desirable to show Forming limit curves for the material that is being tested in order to fully support further results.
The damage model proposed by the authors is a nice derivation of well known damage model proposed by Lemaitre in terms of anisotropy and the results should be highlighted. The reviewers only concern lies in the fact that no error analysis between experimental and simulation results have been performed throughout the whole paper. And the conclusion where the authors say that "The predictability of novel damage model presents good result" without showing the calculated error values seems very salient.
In the reviewers opinion the paper needs to be improved in order to be published in metals.
I suggest major revision, but hope that the authors will be able to improve the paper, because the presented topic would be interesting for the wider audience
Author Response
Response to Reviewer 2 Comments
1. The English language needs to be improved: too many spelling or tense mistakes are located in the text like:
1 page line 20 "directions have lager differences" or page 2 line 70 "aluminium alloy plate were"
Response: The English language has been polished to improve readability. The spelling and tense mistakes have been corrected.
2. While dealing with sheet materials it would be very desirable to show Forming limit curves for the material that is being tested in order to fully support further results.
Response: Thank the reviewer for the worthy comments. The key point of this paper is damage model which coupling Hill48 criterion. This paper mainly investigates the fracture behavior of anisotropic sheet metal under various stress states and verify the modified damage model by hybrid experimental-numerical approach. The forming limit curves for the sheet materials are very interesting, while it is not the focus of this paper, we will further investigate this point in the future.
3. The damage model proposed by the authors is a nice derivation of well known damage model proposed by Lemaitre in terms of anisotropy and the results should be highlighted. The reviewers only concern lies in the fact that no error analysis between experimental and simulation results have been performed throughout the whole paper. And the conclusion where the authors say that "The predictability of novel damage model presents good result" without showing the calculated error values seems very salient.
Response: Some conclusions for modified damage model in terms of anisotropy have been added in the revised manuscript. The conclusion of “The predictability of novel damage model presents good result” is inaccurate. I have revised this conclusion by given calculated absolute error values, in addition, the error analysis between experimental and simulations results has been added.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Dear authors:
Thanks for your kind response. Some figures and their corresponding footers are in different pages in this second version yet. In my opinion the paper is ready for publication after minor edition’s corrections. Congratulations.
Reviewer 2 Report
In the reviewers opinion the authors have changed the paper sufficiently enough so it can be published in metals. I suggest Accept in the present form
