Numerical Simulation of Mechanical Coupling for Low-Back Booster with a 6-Year-Old Child during a Crash Test

Round 1

Reviewer 1 Report

Mechanical coupling for ISOFIX Child Restraint System is investigated in presented research.

In my opinion overal quality of manuscript is good.
Authors team is familiar with the existing state of research in the field of traffic safety (designed equipment for child).

Title of the manuscript "Numerical simulation of mechanical coupling for Low Back Booster with a 6 Years Old Child During a Crash Test" is deal with presented mateerials and with carried-out investigations.
The interpretations and conclusions are sound and justified by the numerical results.

Defence function played by the investigated safety device for child is essential since it is possible to reduce the accelerations suffered by the infant during a traffic accident - front, rear, or side - regardless of the type that arises. 

Author Response

Thank you very much for your comments about the excellent quality of our work. We hope it will be used by the scientific community dedicated to studying child restraint systems and the automotive industry.

Reviewer 2 Report

The subject addressed is current and has interest.

The methodology is supported in literature.

The conclusions are supported in the presented results.

I consider there are some aspects that should be corrected/better described, namely the following:

• In abstract is said “The second evaluates head and chest injuries with a six-year finite element model of Hybrid III through the coupling system during a vehicle collision”; I consider that the phrase is not clear.
• In introduction, in the first sentence, the presented data of infant mortality in road accidents refers to the USA; I consider this country should be referred.
• In the materials and methods section, is said that “the speed reply (of mechanism) is satisfactory”, however, in the article none results are presented related to the speed replay. I consider that in the article should be presented a brief description of the used time integration method and the corresponding time step. For the time step only is referred in the results section, line 184, that the results were obtained for each 1 ms. Is that the time step?
• In the materials and methods section, the effect of suspension box and the coupling links with the cartesian mechanism box are not adequately described. The upper part of figure 1 and the lower part of figure 2 is not clear enough for this purpose. In this part of figure 2 the cartesian coordinate system have a typo -  is presented x instead of z. Also the mounting of the CRS with the cartesian mechanism box is not adequately described.
• In subsection 2.1, in Case 1, I consider that it should be clearly stated, as referred in chapter 1, that the behavior of the proposed mechanism is simulated when subjected to simultaneous lateral and frontal impact. This assumption should not only be verified from the analysis of the initial velocities and corresponding decelerations. The advantage of analyzing simultaneous lateral and frontal impact is also unclear.
• In lines 136 to 139, the text partially describe the mounting of the cartesian mechanism box on the suspension box, but in the referred figure 5 are only presented the joints of the cartesian mechanism.
• In the results section, the description of the results is done previously to the reference of the figures. Sometimes this causes confusion, as it is not known what results the text refers to.
• The results presented in subsection 3.1 could be greatly modified if in the part C of the cartesian mechanism box, were considered the effect of inertial loading of the infant and the CRS. These results could be compared with the ones obtained in the Case 2 for the same components.
• In line 190 is said that “This distance is required to dissipate the energy caused by the later impact…”, it is not clear what is the later impact?
• In lines 192 to 194 the displacement in the z direction is assigned to the force added by gravity – but in the initial position, at time t=0, the system are not in the static equilibrium (in z direction)?
• The stresses and strains fields presented in figure 9, are not perceptible and as referred previously, I consider that these values are greatly dependents of the inertial load mounted in the part C.
• In line 267 there are a typo – should be 54 ms instead of 54 mm.
• In line 317 I consider that the axis should be identified (y).
• There is a typo in the caption of Figure 20, should be Figure 19 instead of Figure 20.

Author Response

Please see attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

I consider that all the issues are properly addressed, clarifying the methodology and the presentation of the results.

Please correct the typo in line 219: it should be “MPa” instead of “Mpa”.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.