The Reliability of the Complex Components under Temperature Cycling, Random Vibration, and Combined Loading for Airborne Applications
Round 1
Reviewer 1 Report
The manuscript presents a study about the strength of a PCB subjected to vibration and thermal cycling. The author performs a comparative analysis between experimental results and numerical simulation.
In the title of the manuscript, it is referred to “for airborne applications”. I understand the logic, but in reality, everything that is presented can be for this specific case or not, that is, “airborne” is just an example.
The work is understandable and tells a story well, however, it is just an application example; I don't think there's anything substantially new. If the author does not agree with this position, then he must clearly indicate what is the novelty of the manuscript.
In the attached file I indicate small flaws that must be checked.
Comments for author File: 
Comments.pdf
Author Response
Please see the attachment
Author Response File: 
Author Response.docx
Reviewer 2 Report
Dear authors,
Your manuscript is interesting from the point of view of the effects of the temperature cycling and random vibrations on the fatigue lifetime and failure modes of the components of the airborne electronic equipment.
The authors must clarify some details and data, which are missing. In order to improve this manuscript, I recommend some major changes and improvement as it is shown below.
1.The goal and the main objectives of the research are not clearly defined in the Abstract section and in the end of Introduction section.
2.The authors must give details about the equipment used for the thermal cycling test.
3. The authors must give details about the equipment used for the vibration test and also, for the combined temperature-vibration test: type and manufacturer for the accelerometers and shaker used, equipment used to measure the resistance and so on. The main characteristics of the equipment are required to completely describe the experimental program.
4.The authors must clarify the type of material for each component of the geometric model shown in Figure 5.
5. It is not sufficient to write that “the boundary conditions were also exactly 177 the same as the real test”. The authors must clarify the boundary conditions defined for the finite element model in Ansys.
6. Table 2: The name of the materials of the component are mixed with the name of the components in the first column called Materials. The name of the material parameters should be given in header of the table.
7.Table 3: The name of the parameters for the Anand model must be given.
8.What kind of finite elements are used for each component of the airborne electronic equipment involved in the research.
9.Why the authors do not report the results obtained for all samples in Table 4, Table 7, Table 9? The average values and stdev must be computed for all results experimentally obtained.
Minor changes:
10.The authors should make corrections regarding the English language and some expressions must be replaced to be more appropriate for the context of the phrase (for example, test vehicle and others).
11.The measure units must be revised in the entire document (Gpa must be replaced with GPa, Mpa must be replaced with MPa).
12.All abbreviations must be written in extended form when it is used for the first time (PCB, PSD, Grms, FR4, BT).
Author Response
Please see the attachment
Author Response File: Author Response.docx
Reviewer 3 Report
The paper must necessarily include nomenclature - a complete list of abbreviations, symbols, markings, etc.
In relation to scientific paper, I do not recommend using the word "work" - preferred words are "scientific paper, manuscript, paper, scientific article". Please correct the article.
The test material should be defined by the word "specimen" following the example of ASTM and BS or ISO standards. I do not recommend using the word "sample". Please correct the article.
Please correct the citations in the manuscript - there is usually no space between the text and the citation given in square brackets, e.g. it is "smaller size[3,4]" - it should be "smaller size[3,4]".
There are errors in the notation of physical units in the manuscript. For example, line 193 is "Mpa" - it should be "MPa", similarly you can not write "Gpa", but "GPa". In the case of the unit of density, it should be "g/cm3" - it is "g/cm3". Please correct this throughout your paper. I recommend not using the scientific notation of numbers - see table 2 - it is "1E-6/K" and should be "1×10-6/K". Units should also be written after a space both in text, tables and figures in the case of axis descriptions.
Please correct tables 1-3. The symbols are incomprehensible - especially in table 3. In the case of yield strength, tensile strength, breaking stress, I suggest using the letters of the Greek alphabet "s" (sigma). Similarly with other markings in the paper - please check the paper in this regard - symbols and markings should be written in accordance with the standards of the MDPI publisher.
Some figures - e.g. 2 and 3, in my opinion are of poor quality, I suggest making them in an application for creating vector graphics (COREL DRAW, ADOBE ILLUSTRATOR), if they are graphs related to mathematics - I recommend the GRAPHER application.
The paper must necessarily include a technical drawing of the specimen used in the research, with all dimensions - please complete the manuscript.
The description of the numerical model raises many doubts. Please prepare and add to the manuscript a figure with marked boundary conditions, loads, and the adopted coordinate system. Please specify in the thesis: what finite elements were used to discretize the model - what was their type, whether they were lower or higher order finite elements, whether one-, two- or three-dimensional elements were used, how many nodal finite elements were, how many points of numerical integration – Jacobian points was in the finite element, how the authors calculated stresses and strains - in nodes or at points of numerical integration. Please provide in your thesis information on the size of the finite elements - what was the relationship between the size of the finite element and the characteristic dimensions used in the testing of the specimen. Please provide information on the convergence of the numerical model - whether it has been tested, which was a qualification requirement for the numerical model to be used in the research.
Please specify the information on the assumed material models in the analysis. It is worth attaching exemplary formulas, constitutive relationships, possible diagrams indicating the appropriate behavior of the material.
The graphs shown in Figure 8 are of poor quality, have errors in the descriptions of the axes - e.g. there is "Stess" - it should be "Stress". The units on the axes are illegible. Please correct the figure. Similarly, figure 7 - it shows nothing but "colored dots" - what is the point of presenting this figure?
Figure 8b - this is not like a hysteresis loop. Didn't the authors confuse the units here and shouldn't it be shown that they are "Pa" and not "MPa"? Please check and explain.
Descriptions of the formulas in the text are sloppily prepared - the formulas contain quantities with subscripts, the authors do not use such a notation in the text. This is unacceptable and hardly deserves publication in the MDPI Journal.
Please organize the manuscript, make any corrections and submit it for review.
I suggest a major revision.
Author Response
Please see the attachment
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
Dear authors,
I read again the revised version of your manuscript which was improved according the recommendations and suggestions of the reviewers.
Although the authors have made major changes, I can recommend publication in the journal Crystals after the authors make the following improvements:
1. The goal and the main objectives of the research are not very clearly defined in the Abstract section and in the end of Introduction section of the revised version of the manuscript.
2. The authors must give additional details about the equipment used in Table 2: main characteristics of the equipment, manufacturer.
Author Response
Please see the attachment。
Author Response File: Author Response.pdf
Reviewer 3 Report
The authors included almost all my corrections in the manuscript. I recommend the manuscript for publication.
Author Response
Dear Reviewers,
Thanks very much for taking your time to review this manuscript. We really appreciate all your generous comments and suggestions!
