Design and Experimental Analysis of an Adhesive Joint for a Hybrid Automotive Wheel

Round 1

Reviewer 1 Report

I am referring to the text by x/y using x=page and y=line numbers respectively or referring to figs, tables, chapters.

You present a nice example for joining of hybrid structures. The proof of concept is based on very basic finite element analyses and with main focus experiments on simplified geometries. Two main critics I have which should be redone:

- What is missing are finite element analyses to evaluate the strenght of the adhesive joint. In such a presentation this is a usual approach to start the development using virtual models and computational analysis. At first analysis and tests on prototypes afterwards as a second step. You changed this sequence. You did not make clear why. Development by try and error is somewhat out of fashion.

- the simplified test setups do not reflect the stiffness of the cylindrical wheel having discs with descrete ribs. Using the simplified geometries for testing, the stiffness of the rim is not caputered correctly by the simplified test design. Finite element analyses to check the applicability of the simplified test setup is missing and should be added. This way you would also include the correct stiffness distribution which will have influence on the stress and strenght in the adhesive joint. You have startet using FEA to analyse stress resultants but not using this to evaluate the simplified test setups in comparison with a real wheel.  Please add this additional study to argue for the test setups you have made.

1/12: I think also the risk for loosening of bolted joints is avoided.

2/56: insulation, not isolation, I guess.

3/106 When you mention product names with trademarks (ANSYS), explain them

Table 2: how do you define nue_xy?

Chapter 2.3.2: what are critical deformations? You mention deformations but what are the allowable limits?

Fig. 3: ist somewhat strange that the reinforcments are in circumferencial direction only. What about cornering. I think this requires also other fiber directions as well.

7/237: for controlled loading and deformation controlled loading, not "regulated".

Fig. 4: the aluminium structure might not be solid and thus will have some stiffness effect on the adhesive layer. Because of lightweight design also aluminum should be removed as much as possible.

Fig. 6: I dont see the big benefit of the linear subcomponent. The machine you are using could also work with a circular rim. I am sure this will give different results for static strength. Also in case of fatigue the local stiffness properties will affect the strength behavior.

Your paper would gain much more value if you take care of the points I have mentioned.

Author Response

Dear reviewer,

thank you for your comments. Please find a response in the attached pdf file.

Kind regards,

Jens-David Wacker

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear Authors,

the manuscript entitled "Design and experimental analysis of an adhesive joint for a hybrid automotive wheel" by Jens-David Wacker and co-workers discusses design, simulation and experimental (laboratory) analysis of  an adhesive joint for a hybrid automotive wheel. The article includes an introduction, the design of an adhesive joint for use in the construction of motor vehicle wheels, simulation studies of the adhesive joint, and experimental tests conducted on a prepared bench. The Authors propose two solutions for the design of the wheel rim and adhesive joint for carbon wheel rims and aluminum wheel discs. Experimental tests were performed on a section of the adhesive joint and included a quasi-static test (for lateral and radial loads) and a residual fatigue test (also for lateral and radial loads). I appreciate the contribution that the Authors made in design process,  simulation studies as well as preparing the experiment and the manuscript. However, in my opinion the manuscript needs to be improved in some fields and some general remarks as well as the specific comments are bellow.

Evaluation of the paper, general remarks, editorial comments/typos:

- The Abstract section should present quantitative results and not only the most important qualitative results and/or generic considerations. Please delete i.e. "Within a federal research project" and add the numerical confirmation for the sentence in line 21 "The test results show sufficient strength of the adhesive joint..." or in line 18 "In addition, adaptations of the fiber layup in the rim area reduce the thermal residual stresses in the joint significantly". Significant improvements are expected in this section of the manuscript.

- line 30 (and others) - there is: "...wheels [1-4]." and should be wheels [1–4].

- line 34 - there is: "...transfer molding [6-7],..." and should be transfer molding [6,7],.

- Note on Chapter 1 Introduction and References: Out of 19 literature sources, only four are scientific articles. Please add information on testing adhesive joints, especially aluminum composites, in Chapter 1. Additionally, include a paragraph on the testing methods for such joints, both destructive and non-destructive. The additional description of the scientific articles will broaden the analysis of the current state of the art in the design, manufacturing, and inspection of adhesive joints and increase the number of references. In its current form, the analysis of the state of the issue is inadequate. Significant modifications are necessary in this chapter of the manuscript.

- line 60-64 - The authors describe the purpose of the project, please modify this purpose and clearly convict what is the scientific goal and what is the utilitarian (practical) goal of your study. Please indicate in this section of the article what its novelty is in relation to the current state of knowledge.

- line 64-67 - information on future research plans should be placed in the last chapter - Conclusions, please remove this information from the Introduction chapter. The same remark is for line 372. 

- line 126 - the Authors have written: "...The load case “L1: straight driving” (see Figure 1b), and “L2: cornering” (see Figure 1c)...", In my opinion this part of the manuscript should be changed: The load case “L1: straight driving” (Figure 1b), and “L2: cornering” (Figure 1c). Please change all this sentence in entire manuscript - also in other chapters. 

- Authors present their results but without any discussion supported by the literature. When the results are not discussed and conveniently supported by the open literature, questionable conclusions are obtained. Currently, the article looks more like a report from simulation and experimental test than a scientific article. Improvement in the description of the test results is required.

- line 340 - Authors have written: "For each test a first crack initiation, located at the edge of the adhesive layer, can be identified in the trend of the curve and confirmed by the visual observation of a video recording of the test.". Please add to revised version of the manuscript pictures for first crack initiation. Did the authors study how the crack spreads?

The above modifications should be implemented before considering the manuscript for publication. I hope these suggestions can help to improve the quality of this paper.

I wish you all the best.

Author Response

Dear reviewer,

thank you for your comments. Please find a response in the attached pdf file.

Kind regards,

Jens-David Wacker

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper is interesting and the studied results are prepared and presented well.

I think it would be worth to extend the introduction a little bit, introducing some scientific research papers about novel joints developed. That would make it more informative and more like a research paper, not like a project report. Such as ‘Preparation and thermodynamic analysis of the porous ZrO2/(ZrO2+Ni) functionally graded bolted joint’

I would suggest to remove the word ‘For the project’, ‘For the objective of this research project’ etc, these are not quite appropriate for a scientific paper and are rarely used. Treat it like a general research.

The material behavior is defined as linear elastic. Did you treat aluminium alloy as linear elastic? What is the justification? Normally the elastic deformation in aluminium is negligible compared with plastic deformation.

Explain more how the thermal loading is applied in FE model.

Figs. 10, 12, try to decrease the numbers shown in x, y axes, i.e., using a larger scale grid.

The conclusions section is a bit lengthy, make it more concise and only include the major general conclusions, not specific results.

Author Response

Dear reviewer,

thank you for your comments. Please find a response in the attached pdf file.

Kind regards,

Jens-David Wacker

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

"Critical deformations of the wheel can be about 5mm, resulting in tyer leakage. This is not discussed at the particular point, due to the focus on the joint behavior, rather than requirements for wheel–tyer intersections."  why not adding this information?

Author Response

Dear reviewer No. 1

Thank you for the feedback.

The missing information is now added in chapter 2.3.2., P4, L152:

"Deformations greater than 5 mm can result in critical tyer leakage."

Kind regards,

Jens-David Wacker

Reviewer 2 Report

Dear Authors,

the manuscript entitled "Design and experimental analysis of an adhesive joint for a hybrid automotive wheel" by Jens-David Wacker and co-workers has been significantly improved. Thank you for taking my suggestions into consideration and making modifications to the manuscript.

The article entitled "Design and experimental analysis of an adhesive joint for a hybrid automotive wheel" can be accepted for publication in Processes Journal.

I wish you all the best.

Author Response

Thank you for your feedback.

Kind regards,

Jens-David Wacker