Material and Damage Characterization of the Elastoplastic Response of the EK4 Deep Drawing Steel
Round 1
Reviewer 1 Report
There are many similar references, please if you can, choose the latest ones.
Author Response
Revised manuscript “Material and damage characterization of the elastoplastic re-sponse of the EK4 deep drawing steel”, submitted to Metals.
The authors thank the valuable comments of the reviewer. The changes in the revised version of this article, which were made according to the reviewer comments, are highlighted in red in the manuscript.
Reviewer #1:
There are many similar references, please if you can, choose the latest ones.
Authors’ answer: Although the cited references seem to be similar, they were discussed in the present work because they cover in detail different aspects involved in sheet metal forming. Moreover, recent references dealing with this application have been considered.
Check language and grammar thoroughly in the manuscript.
Authors’ answer: Grammar and language have been checked by experts after applying the requested changes.
The description of the methods can be improved.
Authors’ answer: This aspect has been improved.
Reviewer 2 Report
Please see the attachment.
Comments for author File: 
Comments.pdf
Author Response
Revised manuscript “Material and damage characterization of the elastoplastic re-sponse of the EK4 deep drawing steel”, submitted to Metals.
The authors thank the valuable comments of the reviewer. The changes in the revised version of this article, which were made according to the reviewer comments, are highlighted in red in the manuscript.
Reviewer #2:
What is each part of the test apparatus in Figure 2?.
Authors’ answer: The names of the components of the setup have been included in this Figure.
Figure 3 is shown three directions with respect to rolling direction but, from the Figure, the anisotropy of EK4 is not obvious. Thus, there is no need to study the EK4 in an anisotropic way.
Authors’ answer: Although the anisotropic character of the material is not apparent in the stress-strain curves shown in Figure 3, this effect can clearly be appreciated in the measured values of the Lankford coefficients. A comment related to this feature was added in Section 3.1.
Figure 8(b) is shown the numerical damage index contours, but what is the numerical gradient corresponding to the color?
Authors’ answer: The color legend for the damage index was added in this Figure.
The formula format and symbol format are not unified in the Section 2.3.
Authors’ answer: The symbol format of all variables appearing in Section 2.3 and 2.4 has been unified.
Check language and grammar thoroughly in the manuscript.
Authors’ answer: Grammar and language have been checked by experts after applying the requested changes.
The description of the methods and the conclusions can be improved.
Authors’ answer: Both aspects have been improved.
Author Response File: Author Response.pdf
Reviewer 3 Report
I have added some remarks in the attached file. Please note them and also take them as information for further paper.
nice paper with regard to material and failure characterization.
Comments for author File: Comments.pdf
Author Response
Revised manuscript “Material and damage characterization of the elastoplastic re-sponse of the EK4 deep drawing steel”, submitted to Metals.
The authors thank the valuable comments of the reviewer. The changes in the revised version of this article, which were made according to the reviewer comments, are highlighted in red in the manuscript.
Reviewer #3:
1.- Erichsen test is only a biaxial test. There is no validation of the stress state shear, uniaxial tensile and between them, which is also necassary in deep drawing. A real component test should be better or cross shape test
Authors’ answer: In the Erichsen test the material is subjected to a stress state in which shear is not dominant. Although biaxial stresses are usually achieved, 3D stress patterns occur when the deformation is very large, forming a localized necking. We add this comment in the introduction.
2.- Not only see e.g. Barlat YLD2000, Banabic Lankfort parameter r0,r45,r90 & rb and yield strengths (σ0,σ45,σ90 & σb).
Authors’ answer: As the reviewer noted, the Barlat YLD2000 model additionally require measurements obtained from the biaxial test. A brief comment in the Introduction was added to clarify this aspect.
3.- The main problem of the tests is the friction and it is difficult to model friction in the simulation due to the constantly changing conditions e.g. friction condition (mixed friction) ,velocity, elongation,... These attempts do not describe all the phenomena involved in the process. Bulge test is better for this application
Authors’ answer: Friction is, in fact, a complex phenomenon. However, the classical Coulomb model has been long recognized to adequately describe this effect not only in sheet forming (see references cited in the manuscript) but also in other forming applications such as wire drawing, extrusion, etc.
4.- The friction of the tribological system is very important and should also be determined.
Authors’ answer: In the present study the applied lubricant was the commercial grease Krytox. The friction conditions for this test were determined by the authors in previous works [4, 5]. A brief comment in Section 2.2.2 was added to clarify this aspect.
5.- Here it should be listed for which materials this applies approximately and a reference to a source should be provided.
Authors’ answer: A reference providing more information on the application of this equation that allows estimating the biaxial stress was added.
6.- Only as a suggestion, see damage and failure model GISSMO. In this model there is no damage accumulation depending on load path and element size.
Authors’ answer: A related comment was included in the Conclusions as future work.
7.- In commercial FE codes (e.g. LS-Dyna) it is possible to define the langford parameter as strain dependent
Authors’ answer: Although our computational code has also the possibility to considered strain-dependent Hill parameters, we adopted constant values in order to simplify the material characterization procedure. A brief related comment was added in Section 3.1.
8.- Almost no anisotropy can be seen here. Why you use a anisotropic material model? Hardening between experiment and simulation does not match although the material model is based on the tensile tests
Authors’ answer: Although the anisotropic character of the material is not apparent in the stress-strain curves shown in Figure 3, this effect can clearly be appreciated in the obtained values of the Lankford coefficients. A brief related comment was added in Section 3.1.
9.- Compare this values to the literature
Authors’ answer: The values of the Lankford coefficients present a maximum error of 17% compared to other tests published by the authors [4]. This is indicated and commented in the new version of the manuscript.
10.- Is this value based on the same lubricant or tribological system?
Authors’ answer: Yes. In the present work we use the same conditions considered in [5], i.e., lubricant (Krytox grease), tools and punch speed.
- Crack should arise at the (near) dom. If not tribological problem-->better lubrication
Authors’ answer: We agree with this remark. However, our intention was to achieve the same experimental conditions as those of Reference [5]. This is the reason why we respect the same tribological conditions and, consequently, we manage to repeat the failure observed in the results of Reference [5] in the region indicated in Figure 8 of the present work.
The description of the methods and the conclusions can be improved.
Authors’ answer: Both aspects have been improved.
Author Response File: Author Response.pdf
