**5. Conclusions**

In this paper, a dynamic model, which integrates TVMS, friction, and time-varying load-sharing ratio, is established, and then combine with the Archard wear model to establish a dynamic wear prediction model. An improved updated method of wear depth is proposed. With help of the proposed dynamic wear prediction model, the coupling effects between gear dynamic behaviors and gear surface wear process can be studied. Surface wear of a gear system results in the increase in dynamic responses, such as DTE, velocity, and meshing force. In turn, the increased meshing force results in faster wear process. Moreover, during the initial wear, the COF decrease slightly due to the reduction in surface roughness, but the friction force increases because of the improvement of dynamic meshing force. The ability of the proposed model in tracking and predicting wear process is superior to the classical static wear prediction model. Compared to the static prediction model, the proposed dynamic prediction model can update the wear depth distribution with wear process. Although the wear depth distributions under dynamic and static conditions are quite approximate in the initial stage, the maximum wear depth of a pinion under dynamic conditions already reaches 1.6 times that of the corresponding quasi-static condition. Therefore, the proposed dynamic wear prediction model is more reasonable for predicting the wear process.

**Author Contributions:** Conceptualization, J.R. and H.Y.; methodology, H.Y.; software, J.R.; validation, J.R. and H.Y.; formal analysis, J.R.; investigation, J.R.; resources, H.Y.; data curation, H.Y.; writing—original draft preparation, J.R.; writing—review and editing, J.R.; supervision, H.Y.; project administration, H.Y. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by National Science and Technology Major Project of the Ministry of Science and Technology of China, gran<sup>t</sup> number J2019-IV-0016-0084.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
