Study on Passenger Comfort Based on Human–Bus–Road Coupled Vibration
Round 1
Reviewer 1 Report
Review of Guichun Wang, Jie Zhang, Xuan Kong “Study on passenger comfort based on human-bus-road coupled vibration” for MDPI journal Applied Sciences on 21/04/2020.
The manuscript describes a human-bus-road coupled vibration system, the dynamic response of the system and the comfort of passengers are studied, the comfort evaluation involves psychosensory consideration with fuzziness of assessment indicators; sevral factors are investigated by parametric study: the effects of interlayer bonding condition of pavement, bus weight, bus speed, and sitting position. The study is within the scope of the journal, however, the evaluation process needs to be verified significantly to ensure the effectiveness of this study and I would suggest a Major Revision for this manuscript.
Here are my questions related to this manuscript:
The 3D road model is proposed in this study, and it is used to generate the prescribed displacement excitation (considering contact coupling). (1) the surface profile is defined using standard, to confirm the correctness with spectral analysis, an sufficient mesh density if required, the authors may wish to verify the effect spatial frequency of the road profile in this study; (2) The road model is in 3D, however, the vehicle model is rigid, i.e., the vertical DOF in the road surface model will used, the authors may wish to explain the connection of the DOF of models from different sources.
The vehicle is considered as rigid body structure with 3 DOFs in this study, this would make the analysis of seat position effect not convincing, as the flexibility (perhaps the location of the engine) would affect this significantly. The authors may wish to justify.
In this study, the effects of interlayer bonding condition of pavement, bus weight, bus speed, and sitting position are parametrically investigted, however, before this multi-factor analysis, a normalization process has to be made, the inputs can be scaled to make this evaluation effective.
The parameters of the vehicle model needs to be justify to confirm the correctness of this study.
Author Response
Please see the attachment
Author Response File: 
Author Response.docx
Reviewer 2 Report
This paper presents the dynamical model of the human-bus-road model and their interaction due to the disturbances on the road, speed of the bus. Even though the dynamical model is discussed in detail, the study wasn't validated through experimental data. The paper in its current state could be a good conference paper however to be published as a journal, the simulation data should be supported with experimental testing.
Also, the reviewer has questions on the dynamical model provided in Eqns. 1 and 5. While writing the lumped model, why the action-reaction forces are considered as external forces? The only input force should be the disturbances from the road as stated in the paper that human keeps contact with the seat during motion. What is meant by Zr(t) being the displacement vector of the asphalt? Does it mean the deviations/disturbances?
It might be good to elaborate on the dynamical model derivations by including the free body diagram of only one human body-seat-bust-road model.
It's been suggested that the authors should collect some experimental data and provide more details on the dynamic models.
Author Response
Please see the attachment
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Thanks for the authors’ response, and I think the presentation has been clear. I am satisfied with most of the replies except for response 3.
With those explanations, it is still difficult to qualify the importance of the factor, it is definitely correct to make calculations on the derivative of the response RMS with respect to different factor, however, it is hard to compare the absolute response RMS values, as the range of independent variables is not well defined, this can be originated from the empirical data for the normal operation, e.g. it is difficult to experience level A-D road profile with close transportation track, and it is also impossible to experience a friction constant from 0.1 to 0.9, except that some evidences can be found.
The author may wish to describe the response 1 & response 2 in the text.
A minor question: the author may wish to adapt the format of the journal.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 2 Report
The paper is substantially improved and the authors responded well to the reviewer's comments.
Author Response
Thanks for the reviewer's positive comments. Really appreciate.
