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The high temperature generated on the contact interfaces of the conical friction element in clutches due to the sliding frictional heat should be responsible for the synchronization failure. In this study, an analytic model taking account of the capsizing moment and stress singularity at the end of the contact interface is established to solve the contact pressure distribution. Then, a three-dimensional finite element model has been developed to analyze the transient thermal behavior of the conical friction element. The contact pressure and temperature distribution generated along the contact interfaces are investigated and compared between the proposed new model, the combined wear assumption, and the uniform pressure assumption. Furthermore, the variations in temperature obtained from the new model and the other two assumptions are compared to the experimental results. The results show that the temperature simulated by the new model has a good agreement with reality. The maximum temperatures obtained by the new model are 95.53 °C and 71.67 °C, and the measured values are respectively 84.98 °C and 65.46 °C at the measuring position under the given two working conditions.

The non-return mechanism is the key device that plays the role of braking in the opening-and-closing electric actuator of an amphibious aircraft hatch door. The ball-and-socket contact pair, providing the pressing force, and the multi-disc friction pair, supplying the braking torque, are two core components in the non-return mechanism. In this paper, the dynamic model of the non-return mechanism is established considering the freedom of rotation-translation. Based on MATLAB/Simulink, the solution framework of the overall dynamic model is built. The dynamic response characteristics of the non-return mechanism in the process of reverse load braking, forward load braking, and continuous closing are analyzed. The braking time and the angular displacement of the output shaft in the braking phase have been presented. Compared with forward load braking, reverse load braking has a longer braking time and smaller angular displacement of the output shaft. In addition, the compaction function of the ball-and-socket contact pair is verified by experiment, and the influence of the cone angle, distribution radius of the ball socket, and the steel ball diameter on the pressing force has been discussed. This study provides a theoretical basis and parametric design platform for the design and optimization of non-return mechanisms, which can shorten the product development time.

The mesh stiffness and contact ratio of gear drive are very important factors which have a great impact on the dynamic load. Contact ratio also affects the fluctuation and the mode of change of the mesh stiffness. In this research, a novel high contact ratio internal gear with a circular arc contact path is introduced. However, the irregular tooth profile of non-involute gear usually causes the numerical calculation to be more complex. To get the torsional mesh stiffness of a pair of internal spur gear, the two-dimensional finite element models of involute internal gear and high contact ratio internal gear are presented and compared. In addition, the influence of input torque on torsional mesh stiffness and contact ratio are analyzed. The mesh stiffness of a single tooth pair and the effect of different engagement positions on mesh stiffness are obtained and compared. Finally, experimental measurement of contact ratio is established by strain gauge technique. It is shown that the torsional mesh stiffness increases with the increase of input torque, and the greater the contact ratio, the smoother the gear drive.