Finite Element Analysis and Experiment of the Bruise Behavior of Carrot under Impact Loading
Round 1
Reviewer 1 Report
The paper is interesting. Methodology and results are designed and performed well. The only small thing is that you use Mpa and the proper typing is MPa.
Author Response
Dear reviewer
First of all, the authors would like to express our deep gratitude to your most helpful comments on our paper entitled “Finite element analysis and experiment of the bruise behavior of carrot under impact loading” .
We have studied the suggestions and comments carefully and revised the paper.
Thank you very much.
Jianneng Chen
Zhejiang Sci-Tech University
Reviewer 2 Report
Please include in section 2 a description of the carrot machining process. What time do you need to machine the compressive specimens? Have you considered carrot dehydration during the machining process? Dehydration affects the mechanical properties of biomaterials.
The standard mentioned at reference [14] fixed a minimum of twenty specimens (chapter 7), no ten specimens as mentioned in line 99 of this manuscript.
As mentioned in equation (1), the Poisson’s ratio was calculated using the length after compression and the diameter after compression. But the measurement of the diameter must be done during the elastic phase of the test, not after the complete test where elastic and plastic strains are introduced in the specimen. Poisson’s ratio is an elastic property, and it must be measured with elastic strains. In Figure 3, there is not any measurement system for the specimen diameter. How have the authors measured the specimen diameter during the elastic phase of the test?
In table 1, change “tangent nodulus” by “tangent modulus”.
Figure 5 only includes the stress relaxation curve of carrot flesh. It is also necessary to include the curve of the carrot core. The stress relaxation curve has been used to estimate the viscoelastic properties of carrots, but it is necessary to perform a creep recovery test to estimate this property. In a stress relaxation test, two material properties are coming into play: viscoelasticity and viscoplasticity. In a creep recovery test, there is a first creep phase with viscoelastic strain and viscoplastic strain, and a second recovery phase with only a viscoelastic strain. Using the curve of this recovery phase of a creep recovery test, the Prony series of a viscoelastic behavior could be estimated. In conclusion, the Prony components estimated with Figure 5 could be a combination of viscoelastic and viscoplastic properties of carrot material.
In the establishment of a finite element model, it is necessary to include the frictional coefficient used in contacts.
What is the initial velocity of the carrot in the simulation?
What are the plastic properties established for the flesh and core of the carrot simulation? Bilinear isotropic, multilinear isotropic, bilinear kinematic, or multilinear kinematic. If a bilinear model is used, after the bioyield point what strain-hardening modulus is used? A value equal to tangent modulus obtained in table 1? I guess that no plastic hardening has been used after the bioyield point because during the dynamic simulation the Von Mises stress does not grow over this bioyield point. Please confirm or refute these statements clarifying in the manuscript how the plastic behavior has been simulated.
I recommend including a graph with a vertical axis of the simulation energies (elastic and plastic energies) versus time. In that graph, the force where yielding occurs would be clearer because the plastic strain energy would be zero until reaching this critical force. In lines 222 and 223, it is said, related with residual stress, that: “This may be because it takes time for stress waves to convert into other forms of energy during the propagation”. The authors should consider another possibility: residual stresses generated due to non-uniform plastic deformation in the carrot. Residual stresses can be generated by the non-yielded region over the yielded region after the impact. The non-yielded region wants to return to its original position, and the yielded region has a permanent deformation.
The maximum timing of the simulation was equal to 5 ms. What is the sense of including the viscoelastic properties, if there is not enough time to show any viscoelastic behavior in that small timing? Have the authors tried to perform the simulation without the viscoelastic properties? It could be that you will obtain similar results without the viscoelastic behavior.
I believe that there is some typing error in the initial part of line 246.
In the experimental tests, what is the initial potential energy for each carrot group? Is there any system to calculate the loss of energy in the rotating joint of the pendulum device? What velocities are reached for these experimental tests? Is the impact velocity reached for the experimental test of 43.1N of maximum impact force like the initial velocity used in the simulations?
Include a table in section 4.2 with the 10 carrots groups, initial potential height, initial impact velocity, maximum impact force, and fruit damage rate.
Author Response
Dear reviewer
First of all, the authors would like to express our deep gratitude to your most helpful comments on our paper entitled “Finite element analysis and experiment of the bruise behavior of carrot under impact loading” .
We have studied the suggestions and comments carefully and revised the paper.
Thank you very much.
Jianneng Chen
Zhejiang Sci-Tech University
Author Response File: 
Author Response.docx
Reviewer 3 Report
The authors have done a good job in connecting simulation and experimental results in their investigation on the bruise behavior of carrot under impact loading. Overall, authors have done a good job in providing results from their studies and discussion.
Author Response
Dear reviewer
First of all, the authors would like to express our deep gratitude to your most helpful comments on our paper entitled “Finite element analysis and experiment of the bruise behavior of carrot under impact loading” .
We have studied the suggestions and comments carefully and revised the paper.
Thank you very much.
Jianneng Chen
Zhejiang Sci-Tech University
Round 2
Reviewer 2 Report
The revised manuscript is acceptable in the present form.
