Loading Rate Dependence of Reducer Hysteresis and Its Influence on Lost Motion Test
Round 1
Reviewer 1 Report
The manuscript contains two distinct sections: a theoretical and an experimental one. The first section introduces a theoretical model describing the hysteresis of the reducers while the second section is dedicated to the presentation of three reducers and their response to various rate change torques using a test set-up made up by one of the authors.
In this form, the manuscript looks like two papers in one: each section has its own introduction, results and conclusions. One expects for a quantitative comparation between the experimental data and the model as a direct way for model validation, and further to be used as a powerful tool in the design of the next generation reducers.
Minor comments: Caption figures and tables could be significantly improved (see for example Figs 12, 13, 14).
The first sentences in many paragraphs from experimental section repeat itself. It should be rephrased or to mention only the differences between various tests. For example, lines 256-260 and 282-285.
Figures 1 and 2, as part of introduction, have limited relevance for the present study being extracted from previous published materials. They could be easily suppressed.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The following comments and suggestions can improve the understanding of the material presented by the authors.
1. There are some English expressions that need to be corrected. For example, in line 32 ‘…it will be rate dependence…’ should be modified to ‘…it will be rate dependent…’. Line 77 ‘The formula is shown in formula (1)’, equation 13 is not clear, etc.
2. In Figure 1 it is written that ‘…the stress increases with the acceleration of the loading rate (line 35)…’. This is not accurate for all the points of the curve. In addition the increase of the loading rate influences the strain. The authors should elaborate on that.
3. Can the authors explain how ‘δ’ is related with ‘θ’?
4. In Figures 12-14 the captions need to be modified to describe in a few words what it is seen in the Figures.
5. Please explain why it is so important the accuracy of the lost motion to such detail so it is necessary to include the rate dependance.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The paper aims to investigate the rate dependence and rate independence of the hysteresis phenomenon. A system that typically has hysteretic behaviour is the reducer.
Studies on the hysteretic behaviour of reducers are numerous, but most of them do not consider rate dependence features. For this reason, the effects of loading rate dependence on the reducer are not included in the design and testing of the lost motion of the devices, resulting in incomplete and questionable results. In this regard, this research aims to fill this gap by evaluating the loading rate dependence and its effect on lost motion tests through experimental tests on three reducers produced with different materials.
In the light of this review, the topic is certainly of interest to the journal and the results obtained could be relevant for the design of the reducers, but should be further investigated and explained in more detail.
Overall, the article is not completely satisfactory and present some element of concern that have to be solved before the publication in the journal. More specifically, the layout of the article needs to be improved to make it clearer and more readable.
· The quality and resolution of the images must be improved.
· Language and grammar need to be reviewed.
· Introduction. As the article has a complex structure, at the end of the section introduction, it is suggested to insert a more detailed overview of the paper structure with a summary of the covered topics.
· Please, line 41. Please, Mention also other materials, such as the one dealt with in DOI: 10.1016/j.conbuildmat.2011.06.071
· Section 2.1.,rows 76 - 78: The symbolism adopted is not clear. It is also unclear what some of the symbols refer to in the Figure 4.
· Section 3.4.: Whereas the experimental campaign plays an important role in this study, it is recommended to add a complete overview with the features of the testing machine. Also, it is suggested to add some photos of the experimental campaign, for better comprehension.
In this section, the details of the experimental campaign are poor. What are the specimens’ features (shape, geometry, dimensions)? Some characteristics are mentioned but are not clear. It is advisable to show them on a schematic drawing of the device.
It is also suggested to insert some photos of the specimens used for the tests.
· Section 3.4., row 240: The authors state that Figure 11 shows "a design of small-sized reducer created by the author". Figure 11 illustrates the testing machine instead. Please correct the mistake.
· Section 4: The testing conditions are not clear. Please explain how the loading rates and the three different measuring positions are chosen.
· Reviewer comment: The test procedure and all its details should be described more clearly and in more detail, perhaps combining them in one paragraph for all types of specimens.
· Section 4.1., row 261 – 263: What is the meaning of “According to the experiences in practice of engineering”? Please add some references.
· Reviewer comment: The results of the experimental tests need to be described in more detail. It is recommended to comment on them not only qualitatively but also quantitatively, adding and discussing the numerical values obtained. Since the results are reported in a confusing way, it is suggested to include them in a dedicated paragraph. It is also suggested to include a paragraph comparing the results, in order to highlight more clearly the differences observed between the three devices.
· Reviewer comment: How small-size reducers differ from full-size devices? How were the devices designed by the authors?
· Figure 6: It is advisable to use more easily visible colors to make the figure more readable.
· Figure 10: What is the δe factor you mention in line 234?
· Figure 11: Please identify the components of the test apparatus in the figure for greater clarity.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The new version of the manuscript was improved at large and one appreciates the effort made by the authors to address the reviewers comments and suggestions. Moreover, one acknowledges authors view to let the quantitative analysis of the model for a future project / paper.
Unfortunately, the manuscript still looks like two papers in one, even if to a less amount compared to the 1st version. The model section should be linked with the second part of the manuscript even if it is just a qualitative analysis, in order to justify its relevance for an experimentalist. Firstly, the authors should provide some curves which indicates the model response to parameters variation (at least the most important ones). Secondly, they should discuss and indicates (ideally with a fit) to what extent the model is capable to reproduce qualitatively (at least) the experimental hysteresis curves and their specific shapes. In this way, the model will be validated and its usefulness will be transparent for everybody.
Without these supplementary data, I can not support the publication of the manuscript.
Author Response
Thank you for your comments. Your comments are very helpful to us. We have also taken this issue into consideration. We have carried out follow-up research.
As a key index to evaluate the transmission accuracy of the reducer, the lost motion has important research value. However, in the lost motion test, the tester will not consider the impact of the loading rate on the test.
In fact, this paper has found a phenomenon in engineering practice, that is, the loading rate will affect the lost motion test. After finding this phenomenon, we qualitatively analyzed the causes of the hysteresis phenomenon of the reducer. Theoretically, we found that the hysteresis phenomenon of the reducer is dependent on the loading rate, rather than independent of the loading rate, and has an impact on the test results of the lost motion. Finally, the experimental study is carried out to prove the existence of the loading rate dependence and its influence on the lost motion. Therefore, the value of this paper is to prove the existence of this phenomenon through qualitative analysis and experimental research. We believe that the qualitative research in this paper has revealed the loading rate dependence in the hysteretic characteristics of the reducer, and explained the cause of this phenomenon and its influence on the lost motion. To a certain extent, the research results fill the gap in this field and can make a reasonable analysis of some phenomena in actual use, which is of guiding significance for follow-up research.
For quantitative research and parametric model research, it is of great significance to study the loading rate dependence, but it is not the purpose of this paper. As for the research in this area, we have already carried out relevant work. Due to the length of the article and the need to refine some work, we will not make more explanations in this paper. As for the research results of this phenomenon, we will continue to contribute to machines, hoping to form a series of articles. Thank you for your comments.
Reviewer 3 Report
All my queries have been considered in the revised version of the paper.
Author Response
Thank you for your comments.
