Applied Mechanics and Materials Vols. 427-429

Abstract: The method of handling respectively is used to refine the grid of ducted fan with coaxial rotors. Research the complex flow field of the ducted fan by numerical simulation to analyze its hover characteristics. The curve of the upper rotors lift, the lower rotors lift, the ducts lift with collective and the distance between rotors is got respectively. By comparing with the aerodynamic characteristics of ducted fan with a single rotor, results show that there is interference between the upper and lower rotors, the upper one interferes the lower one more heavily and interference is reduced with the increase of distance between the rotors; the duct of ducted fan with coaxial rotors can provide more lift than the one with a single rotor.

Abstract: This study has established a 1/184 model of blade root by using finite element software (ANSYS), and analyzed the stress pipeline and errors of this blade root model. By transforming the loads in blade root and imposing axial step load, especially by analyzing models boundary conditions and the structure of contact surface, the axial stress, bending stress and the other parameters have been acquired.

Abstract: Temperature field of sector cavity multi-pad hydrostatic thrust bearing is significantly affected by flow capacity, and different flow capacity can carry different shearing heat, so temperature field of oil film is obviously changed. For this problem, the lubrication theory and the Computational Fluid Dynamics have been used to simulate influence of flow capacity on temperature of sector cavity multi-pad hydrostatic thrust bearing, to gain relationship between inlet flow capacity and temperature of sector cavity multi-pad hydrostatic thrust bearing, achieve the optimal design of such products. Results are shown that along with the flow capacity increasing, the temperature of hydrostatic thrust bearing also becomes lower under constant rotational speed condition.

Abstract: Inter turn short circuit fault is very common for turbine-generator, which will produce unbalanced electromagnetic force (UEMF) together with its relevant fault, namely dynamic eccentric, on the rotor. After complete finite element simulation by ANSYS, The relationship of rotor winding short positions and short degrees with UEMF were studied. And then, only the dynamic eccentric fault occurs, the relations of dynamic eccentric angles and dynamic eccentric degrees with UEMF were discussed as well. Whats more, by comprehensive consideration of the two faults, the characteristic of the force and its change law were researched. This paper provides a viable path to study the vibration law and fault diagnosis of turbine-generator in multi-source stress.

Abstract: Electric hydraulic power steering system (EHPS) has the characteristics of high energy efficiency and reliability. In this paper, we focus on the design and analysis of assist characteristic for EHPS of electric bus. The relationship of steering assist power, steering wheel torque and steering resisting torque was analyzed; steering system model and vehicle dynamic model were built. By EHPS simulation, the relationship of pump flow rate, steering wheel angular velocity and vehicle speed was deduced and 3-D assist characteristic curve map was plotted, which was suitable for electric bus. In order to apply the assist characteristic curve into practice, we optimized the curve through BP neural network, and then obtained the assist power value under any vehicle speed and steering wheel angular velocity. Finally, EHPS simulation verified the optimized assist characteristic curve having a good performance.

Abstract: Adjusting plate design method of pantograph based on envelope theory is explored in this article. When pantograph is raising at a constant rate, the loads on adjusting plate are considered. Envelope theory is used to establish the adjusting plate design method of pantograph. Finally, Design method based on envelope theory in the application of V500 pantograph proves the feasibility and effectiveness.

Abstract: The law of wheel wear is the basis for making turning repair cycle, and is one of the most important guarantees for the safe and stable running of train. A statistical analysis of individual wheel wear parameter was carried out based on wheel profile data of CRH2. The change law of individual wear parameter with mileage showed that wear process of wheel could be divided into two periods: the run-in period and the stable wear period. The paper has realized to research on the correlation between nominal wheel diameter abrasion value and wheel flange thickness variation based on Copula, too. Frank Copula was selected to describe correlation of the two wear parameters, the correlation index (α) of Frank Copula was estimated and the joint distribution function considering dependence was given. The value of α indicated that there was a weak positive correlation between the two wears, which can be ignored for calculating the accumulative failure rate of wheel wear. So the two wear parameters can be regarded as independent random variables during failure analysis of wheel wear.

Abstract: By using of the principle of the reverse engineering and CATIA V5 software, the torque rheometer mixer rotor used in high polymer material test is designed. The POWERMILL software is used for NC programing and manufacturing simulation, the MIKRON UCP710 five axis linkage processing center is used for manufacturing. The practical application of this rotor on torque rheometer proves that this rotors structure design is reasonable. The test requirement of torque rheometer is well satisfied. This kind of rotor has a very good promotion value.

Abstract: In order to investigate self-excited vibration mechanism of wheel-rail lateral contact system, a two DOF elasticity position wheelset lateral vibration model is established which considers the dry friction; the mechanism of the wheelset lateral self-excited vibration is investigated from the energy point of view. It shows that: the bifurcation diagram of this wheel-rail lateral contact system has a supercritical Hopf bifurcation. The energy of self-excited vibration derives from a part of traction energy; the creep rate in the wheel-rail system act as a feedback mechanism in the wheelset lateral self-excited vibration system. The stability of the wheelset self-excited vibration system depends mainly on the total energy removed from and imported into the system.

Abstract: In order to solve the mechanical deformation of the hydrostatic center rest, a numerical simulation concerning pressure field of hydrostatic center rest is studied. CFX of ANSYS has been used to compute three-dimensional pressure field of gap fluid between workpiece and bearing pillow. This research analyzes the influence of rotation speed on the bearing pressure performance according to lubricating theory and computational fluid dynamics, and it has revealed its pressure distribution law of gap oil film. Results indicate that an improved characteristic will be affected by rotation speed easily, and oil cavity pressure increases by gradually with rotation speed enhancing. The reliability of a hydrostatic center rest can be predicted through this method.