Effect of Elastic Module Degradation Measurement in Different Sizes of the Nonlinear Isotropic–Kinematic Yield Surface on Springback Prediction

Round  1

Reviewer 1 Report

- Eq. (1) is wrong, please check.

- Chord modulus model (Eq. (1)) and Eq. (3) are basically same. The method to fit the model is different. It cannot be said as "New model".

- It seems that chord model and QPE model do not combined with Chaboche model because I could not find the coefficients of Chaboche model.

- If previous comment is right, FE simulations should be re-performed. Table 2 is wrong comparison.

- In Table 2, 25%σ case leads the most accurate simulation result. I 'd like to know whether 25%σ method is best for other advanced high strength steel sheets or not. More validation is necessay.

- The comparison of flow curve and springback profile between experimental and simulated results should be presented.

- The computation time for each model should be presented.

Author Response

Dear Review:

- It seems that chord model and QPE model do not combined with Chaboche model because I could not find the coefficients of Chaboche model.

- If previous comment is right, FE simulations should be re-performed. Table 2 is wrong comparison.

yes, you are right for the missing of some parameters. I have added all the missing parameters in Table 1.

For the Isotropic hardening model, we don’t need to Chaboche model because there is no back stress in isotropic model. It just expending by the size of the yield surface.

But for the simulation are correct. all parameters that add in table 1 are included in simulation. the reason I did not write the missing parameters because I was writing in hurry. Even I add complete hardening model for the other model

- The comparison of flow curve and springback profile between experimental and simulated results should be presented.

- The computation time for each model should be presented.

The springback profile , computation time and the validation of the model to other material are update in the new revision of the manuscript.

Thank you in advanced

Author Response File: Author Response.docx

Reviewer 2 Report

Overall, the English language of the paper is very poor, which makes it very hard to follow. It gives the reader the impression that it was written in a hurry and in a very careless manner.

Below are some examples of English language problems (out of many):

 "to predict the final shape simulation more accuracy (accurately)"

"The new model was verified compare (compared) with U-draw bending"

"Von miss (von Mises)"

"Von Miss (von Mises)"

"the model was devolved (developed)"

There were no pictures or, at least, schematic diagrams of the experimental setup presented.

A lot of assumptions regarding simulated values for springback parameters were introduced. It is very hard to follow from the paper how these simulations were unfolded.

There are few simulation condition descriptions presented and practically no simulation diagrams (screenshots from the software?).

A lot of measured (experimental) values were presented in the paper. How were these values measured? What measurement systems (optical?) were used?

How where the samples prepared for measurements?

Author Response

Dear Reviewer

For the English language problems, I have applied for editing English language in the new revision in the manuscript

A lot of assumptions regarding simulated values for springback parameters were introduced. It is very hard to follow from the paper how these simulations were unfolded.

There were no pictures or, at least , schematic diagrams of the experimental setup presented

A lot of measured ( experimental) values were presented in the paper. How were these values measured?

The simulation work in this study is carried out based on the experimental data from the Numisheet 2011 benchmark study of the 8th International Conference and Workshop on Numerical Simulation of 3D Sheet Metal Forming Processes.

Benchmark study of the 8^th international conference and workshop on numerical simulation of 3d sheet metal forming processes. Proceedings of Numisheet 2011.

This is a standard method when working with limited data. Many researchers have adopted to this similar approach, using confirmed published experimental data for comparison purposes when working in the simulated environment.

I have update new figure of springback profile compare with the exprement.

There are few simulation condition descriptions presented and practically no simulation diagrams (screenshots from the software?)

I have already taken screenshots from the software for the model and I uploaded it in the new revision of the manuscript.

thank you in advanced

Author Response File: Author Response.docx

Round  2

Reviewer 1 Report

- In Table 1, there are still missing information. In QPE parameter, what is the H_I (=3846.9) ? Is this parameter for nonlinear kinematic hardening?

- In Eq. (7) & (8), the authors wrote that there are two "yield" surfaces in QPE model. What is the plastic yield surface of them? From reference, QPE model has two surfaces, one is the surface defining the elastic-QPE transition, and another one is the surface defining the plastic deformation.Because I do not think you use two-yield surface kinematic hardening model, please correct it.

- Figure 5: Several models were used for FEM. Isotropic means Isotropic hardening + E₀ case. Chord model means Isotropic hardening + chord E case. Other two models (QPE model, 0.25 of stress forward) used Chaboche hardening. Is this right?

If right, two simulations, Isotropic & Chord, produce strange results. I understand the effect of the Elastic modulus on the springback prediction, but too much difference in profile is shown in figure. And also please see the paper (IJSS 49(25) pp.3562-3572).

- I'd like know the stress-update algorithm for plastic deformation, for example, forward Euler method, Backward Euler method or cutting plane algorithm...

Author Response

Dear reviewers

I have upload word file for your comments

thank you in advanced

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors have significantly improved the paper, following the reviewer suggestions.

It is now a fair scientific paper of average scientific merit and I consider it could be published in the Metals journal.

Author Response

Dear reviewer

I have just remove one parameter from Table 1 

that is my update

thank you 

Author Response File: Author Response.docx

Round  3

Reviewer 1 Report

Nice work