As key components to transmit power and motion between intersecting shafts, it is necessary to design feasible tooth axial modification to improve the meshing performance and bearing capacity of straight bevel gears. The main purpose of this paper is to propose an effective axial modification method of straight bevel gears considering alignment errors. In this paper, the meshing performance of two kinds of tooth axial modification method (tooth end relief and symmetric crowned modification) for straight bevel gears is investigated by the finite element analysis (FEA). The results show that the tooth end relief is an optimal method to enhance the meshing performance of gears in different installations for decreasing transmission errors, reducing maximum contact stress and bending stress and improving the distribution of contact stress and bending stress. This research provides a suitable tooth end relief method of straight bevel gear with alignment errors.

In cold orbital forging (COF) processes, large stress, displacement and vertical vibration of the COF machine are bad for the quality of the part and the fatigue life of the COF machine. It is necessary to investigate the static and dynamic performance of the COF machine and provide methods for reducing the stress, displacement and vertical vibration of the COF machine. In this paper, finite element analysis, theoretical analysis, numerical simulation and experimental analysis were applied to study the static and dynamic performance of a 6300 KN COF machine. The static and dynamic analyses were verified effectively by carrying out strain and vertical vibration test experiments. In the static analysis, the large stress and displacement positions of the COF machine were mainly distributed near the working table and the junction between the working table and the column. Large stress and displacement will be bad for the quality of the part and the fatigue life of the COF machine. Structural optimizations of the COF machine include ribbed plates on the working table and beam. This structural optimization method of the COF machine obviously reduced the stress and displacement of the COF machine. When the angular velocities of the eccentric rings were 8π rad/s, the vertical vibration of the swing shaft is a low-frequency vibration. The existence of absorber obviously reduced the vertical vibration of the COF machine.

As the core components of mechanical power system, triple-phase asynchronous motor and reducer are required strictly for temperature control. In this paper, the triple-phase asynchronous motor and the reducer are regarded as a coupling system, and thermal network method is used to predict the temperature field distribution of the coupling system. The predicted temperature of the thermal network method is consistent with the experimental result and the finite-element analysis. Furthermore, analysis shows that motor output power, coefficient of friction between teeth and lubricating oil parameters have a great effect on reducing the temperature of the coupling system.

With the continuous development of the maritime economy, the maritime unmanned surface vehicles (USVs) and unmanned aerial vehicles (UAVs) have become important parts of the maritime transportation system. Unmanned vehicles play a pivotal role in water safety management, offshore patrol and maritime rescue. Consequently, this article researches and develops an unmanned aerial vehicle–unmanned surface vehicle (UAV-USV) coupling system with multiple functions. The ship body module, the deformation module and the UAV module are designed by using the modular analysis method, then volume of fluid (VOF) technology and STAR-CCM+ software are applied to analyze the ship resistance before and after deformation and optimize it. The results show that the Transformer has high speed before deformation and stable navigation ability after deformation, and it can navigate in high winds and waves. It has a large reconnaissance range and some radar stealth capability, which can fulfill different tasks, such as maritime patrol, military strike and maritime rescue.

The vibration of cold orbital forging (COF) machines is a major issue for the quality of forging parts. It is therefore necessary to investigate the vibration of COF machines and provide some effective methods for reducing the vibration. In this paper, horizontal and vertical dynamic models of COF machines are established. These dynamic models are then effectively verified by conducting experiments. By using dynamic models of the COF machine, the vibration performance of the COF machine is investigated. To investigate methods for reducing the vibration of the COF machine, the effects of some key parameters on the vibration of the COF machine are studied, which include the eccentricities and rotation angular speeds of the inner eccentricity ring and the outer eccentricity ring, the amplitude and frequency of external excitation, and the equivalent stiffness and equivalent damping between swing shaft and bearing. Investigative conclusions can be drawn: During the COF process, vertical vibration is more drastic than horizontal vibration. A larger absolute difference between the eccentricities of the inner eccentricity ring and the outer eccentricity ring contributes to reducing the horizontal vibration of the COF machine. A larger equivalent stiffness and a larger equivalent damping between the swing shaft and bearing, a smaller amplitude and a smaller frequency of the external excitation contribute to reducing the vertical vibration of the COF machine.