In the field of aerospace, high-speed trains and automobile, etc, analysis of temperature filed and scuffing failure of tapered roller bearings are more important than ever, and the scuffing failure of elements of such rolling bearings under heavy load and high speed still cannot be effectively predicted yet. A simplified model of tapered roller bearings consisted of one inner raceway, one outer raceway and a tapered roller was established, in which the interaction of several heat sources is ignored. The contact mechanics model, temperature model and model of scuffing failure are synthesized, and the corresponding computer programs are developed to analyze the effects of bearings parameters, different material and operational conditions on thermal performance of bearings, and temperature distribution and the possibility of surface scuffing are obtained. The results show that load, speed, thermal conductivity and tapered roller materials influence temperature rise and scuffing failure of bearings. Ceramic material of tapered roller results in the decrease of scuffing possibility of bearings to a high extent than the conventional rolling bearing steel. Compared with bulk temperature, flash temperature on the surfaces of bearing elements has a little influence on maximum temperature rise of bearing elements. For the rolling bearings operated under high speed and heavy load, this paper proposes a method which can accurately calculate the possibility of scuffing failure of rolling bearings.

In this study, we obtained dodecagonal monolayer silicene with three-fold and four-fold coordination by melt quenching via molecular dynamics (MD) simulations. Stretching simulation of the pre-strained dodecagonal silicene showed lower critical stress than the honeycomb silicene and resulted in an increase in six-fold rings during the plastic deformation since the four-coordinated atom sites are less mechanically favoured than the three-coordinated sites. The friction behaviours with an AFM tip sliding on the dodecagonal and honeycomb surfaces under different loads and tip sizes were simulated and compared. For all the investigated cases, the dodecagonal surface always showed a lower mean friction force than the honeycomb surface. The lower friction of the quasicrystal was observed, and the mechanism was illuminated successfully for the first time by MD simulations. The reduced friction of dodecagonal silicene can be explained by the morphology of the one-dimensional potential energy surface (PES). The 1D PES of dodecagonal silicene has longer potential corrugation lengths than honeycomb silicene, which induce mild motion of the tip in the stick process and lower friction force. Considering the close density of the employed dodecagonal and honeycomb structure, the longer potential corrugation length is a consequence of the quasiperiodic morphology rather than the interspace between atoms. Besides, with a larger tip size, the 1D PES on the dodecagonal surface has a flatter area, which contributes further to the reduced friction force on the dodecagonal surface.

The rotary vector (RV) reducer is one of the widely used mechanical components in industrial systems, specifically in robots. The stability of the transmission performance of the RV reducer is crucial for the efficient operation of industrial equipment. The manufacturing and assembly errors of various components of the RV reducer during the production process are important factors that affect the transmission performance. However, in previous research work, the coupling effect of multiple errors on the transmission accuracy of RV reducer has not been fully considered. Furthermore, a vague relationship between system transmission errors and various errors also has not been thoroughly discussed, which presents a challenge to analyze and optimize the errors of components using the simulation technology of virtual prototype. Therefore, we propose a novel approach to use the response surface method (RSM) to investigate the transmission accuracy of RV reducer. Firstly, based on the constructed virtual prototype of RV reducer, the individual effects of different original errors on the overall transmission error are analyzed. Secondly, a response surface approximation model using RSM is constructed to analyze the effect of multiple error interactions on the transmission accuracy of the RV reducer, and the potential functional relationship between multiple error factors and the overall transmission error is also explored. Finally, the authenticity of the proposed approach is verified by setting up some comparative experiments. This study provides a reference for the efficient analysis and optimization of the transmission accuracy of RV reducers.

：For deep groove ball bearing, the rolling contact model of ball, inner and outer raceways is established. The motion characteristics of rolling bearing are considered in the calculation of fatigue life. A more accurate load distribution calculation model is proposed by considering the number of rolling elements loaded in the ball bearing. Effects of different clearance and speed on load distribution inside the bearing under the same external load are analyzed. For four different motion states of deep groove ball bearing, contact stress variation of points on inner ring, outer ring and ball was computed, and the load sequences are analyzed. The Lundberg-Palmgren (L-P) life model is modified to consider the influences of different motion states on the number of stress cycles in the bearing. The lives of inner race, outer race, rolling elements and the overall bearing are calculated. The lives under different motion states are compared with both the L-P model and the new modified L-P model, which show well agreement under the situation when one of the races is rotating; however, when both of the races are rotating, the lives of bearings calculated with the modified L-P model and the L-P model are quite different from each other.