Meshing force of misaligned spline coupling is derived, dynamic equation of rotor‐spline coupling system is established based on finite element analysis, the influence of meshing force on rotor‐spline coupling system is simulated by numerical integral method. According to the theoretical analysis, meshing force of spline coupling is related to coupling parameters, misalignment, transmitting torque, static misalignment, dynamic vibration displacement, and so on. The meshing force increases nonlinearly with increasing the spline thickness and static misalignment or decreasing alignment meshing distance (AMD). Stiffness of coupling relates to dynamic vibration displacement, and static misalignment is not a constant. Dynamic behaviors of rotor‐spline coupling system reveal the following: 1X‐rotating speed is the main response frequency of system when there is no misalignment; while 2X‐rotating speed appears when misalignment is present. Moreover, when misalignment increases, vibration of the system gets intricate; shaft orbit departs from origin, and magnitudes of all frequencies increase. Research results can provide important criterions on both optimization design of spline coupling and trouble shooting of rotor systems.

The coupled longitudinal and transverse vibration characteristics of a submarine propeller-shaft-hull system at low frequency are studied in this paper. Two substructures, which are the propeller-shaft subsystem and the submarine hull, are first modelled using the finite element method. The two substructures are then connected through bearings, which are simplified as longitudinal and lateral springs and dampers. The modes, the natural frequencies and the coupled vibration characteristics of the two substructures and their synthesized system are simulated. An experiment studying the dynamic characteristics of a large-scale submarine test-rig is proceeded and compared with the numerical results, showing great consistency. Finally, transfer path analysis of the low frequency excitation forces using power flow method is discussed.

Porous asphalt pavement can reduce noise and improve road safety and driving comfort on rainy days. The seepage model derived from the one-way gradient flow theory cannot truly reflect the seepage process of rainwater inside the drainage layer. In this study, the drainage performance of porous asphalt pavement with different designs was evaluated using a three-dimensional seepage finite element method (FEM), and the drainage capacity of porous asphalt pavement was calculated using short-term rainfall intensity. The results indicated that the drainage capacity of porous asphalt pavement can be effectively improved by increasing cross slopes, the surface course layer thickness, and the permeability coefficient of porous asphalt mixture. Moreover, the pavement width had a significant impact on the drainage performance of porous asphalt pavement.

The application of electric field has been demonstrated as an effective way to enhance pool boiling heat transfer. In past studies, adiabatic experiments were often conducted to simulate the dynamics of nucleate bubbles in the presence of an electric field, where gas bubbles were injected from an orifice, to avoid complexities involved in the nucleate boiling experiments. While adiabatic studies yield useful information of the bubble dynamics, further studies about bubble dynamics during nucleate boiling heat transfer are still necessary for a full understanding of the effects of applied electric field on the liquid-vapor phase change heat transfer. In this paper, the dynamics of a single boiling bubble in a direct current (DC) electric field was studied experimentally employing R113 as the working fluid. The life cycle of the boiling bubble was visualized using high-speed photography and was compared with that of an injected nitrogen bubble. Under the same electric field, a more appreciable elongation along the field direction was observed for the boiling bubble. A modified relationship between the bubble deformation and the electrical Weber number was proposed for the boiling bubble. As the electric field strength increases, it was found that, although the growth time of the boiling bubble increases, the waiting period decreases. However, it was also found that, the change of the whole life cycle with electric field strength increasing is relevant to the wall temperature. In this work, the wall temperature measured in the vicinity of the nucleation site upon the bubble departure decreases when the electric field is applied.

A dynamic model for wheeled planetary rovers based on the pseudo-coordinates approach is presented. The model allows any number of wheels and different types of suspensions to be considered and can used for rovers steered by steering wheels or by slip steering. As an example, the dynamics of a large 8-wheels pressurized rover for lunar exploration is studied.