Applied Mechanics and Materials Vol. 703

Abstract: Through the mechanism of the gearbox’s vibration signal and establish the corresponding mathematical model, then establish a fault diagnosis method based on the wavelet theory and Hilbert demodulation spectrum. First, the wavelet threshold de-noising can be used to reducing noise of the gearbox’s vibration signal. Then, use the wavelet packet decomposition to decomposing the de-noising signal into different frequency band. After that, use the Hilbert transform to demodulate the frequency band that focused power. Finally, extract the fault characteristic value for the fault diagnosis. Through a fault simulation vibration signal test the method, the results show that the method can effectively extract the fault information of the wind turbine gearbox.

Abstract: A nonlinear blind separation method of mechanical fault sources is proposed. In the proposed method, the signal is transformed from the low-dimensional nonlinear original space into a high-dimensional linear feature space by the kernel function, so that nonlinear mixture mechanical fault sources can be separated by the linear ICA method in a new feature space. The simulation result shows that the proposed method is superior to the traditional ICA method in processing nonlinear blind separation problem. Finally the proposed method is applied to the nonlinear blind separation of bearing faults. The experiment result further verifies the validity of the proposed method.

Abstract: To study the effects of the nonhomogeneous material properties on the stress in an induction quenched crankshaft, the FEM model considering the nonhomogeneous material properties was established to simulate the stress in the crankshaft under the explosion pressure. Results showed that the nonhomogeneous properties almost didn’t vary the Mises stress distribution rule in the crankshaft. The maximum Mises stress, the ratio of the elastic modulus of the surface layer and the matrix followed a linear rule nearly. Moreover, the maximum Mises stress increased with the ratio. Besides, effect of elastic modulus distribution in the transition layer on the maximum stress could be ignored. To simplify the establishment of the FEM model, the elastic modulus could be set to either equal to the surface layer’s or the matrix’s.

Abstract: In-wheel motor driving electric vehicle is an important development direction in the future. Aiming at the in-wheel motor used for electric vehicle, a comprehensive analysis of its present design and application situation was made, then the performance characteristics of in-wheel motor driven electric vehicle was proposed. Moreover, the concept and structure of in-wheel motor system were stated, and the current development situation of its each part was expounded. Finally, on the basis of analysis of the positive and negative effects on the performance of electric vehicle, the key technical problems concerning in-wheel motor system design and the solutions were summed up.

Abstract: A transmission efficiency calculation model of planetary geared reducer was proposed in this paper. The power losses of meshed surfaces of sun-planet gears and planet-ring gears were analyzed in detail. Finally, the mechanical power losses and transmission efficiency of the planetary gear reducer were simulated to illustrate the influence of rotational speed and torque on mechanical power loss and transmission efficiency.

Abstract: To deal with the complicated spiral surface of screw pump,this article uses Pro/E to build geometry model.And it improves the method of the grid topology to use the dynamic grid ideas.At the same time,using the method of Computational Fluid Dynamics to numerical simulation for full-metal single screw pump,analysis and study that viscosity affect leakage properties,the torque of surface of rotor and the volumetric efficiency.

Abstract: As an important component of maglev wind generators, magnetic bearing should possess the merits of small volume, light weight, lower consumption and so on. A novel low-loss axial hybrid magnetic bearing (HMB) is proposed in this paper, its structure and operation principle are introduced, and the process of producing suspension force is elaborated. Based on equivalent magnetic circuit method, magnetic circuit models of PM and control coil are analyzed and established to deduce the quotation of axial levitation force. The accuracy and the reasonableness of proposed low-loss axial HMB are analyzed and validated by using finite element method (FEM), and the comparison between theoretical calculation and FEM is given, which indicates the proposed HMB exhibits good dynamic response and easy control.

Abstract: Compared with traditional screw pump,all-metal screw pump have more advantages in the oil extraction. In this paper, all-metal single screw pump's geometric model was made by PROE software; then the dynamic mesh technique was applied to mesh the model and constraint condition was applied in the ANSYS-FLUENT software. 3D flow field was numerical analyzed In that software, the impacts of screw speed on volume flow and volumetric efficiency were concluded, the conclusion can offer some valuable guidances to the all-metal single screw pump's design.

Abstract: The generation III nuclear technology (AP1000) has been introduced into China since 2006 along with the project of 1000 MW advanced passive pressurized water reactors which is a development of any of the generation II nuclear reactor designs incorporating evolutionary improvements in design developed during the lifetime of the generation II reactor designs. The low pressure rotor of nuclear turbine for AP1000 is currently the heavy forging which requires the use of the heaviest steel ingot and possesses the maximum weight and cross sectional area in the world. The forming and manufacturing technology of such heavy forging have been described in this paper.

Abstract: Abstract. In this paper, a new type of maglev wind generator is proposed. The working principle, structure characteristics and the finite element analysis of the new maglev wind turbine are introduced. The generator consists of a 2 degrees of freedom (DOF) maglev generator and a 3 DOF hybrid magnetic bearing. An eight poles active magnetic bearing with external rotor is added into traditional direct-drive permanent magnet wind generator. The rotor ring is hollowed, which can leads to the self-decoupling for magnetic fields between power generation system and suspension system. Compared with the conventional maglev wind generator, the proposed generator not only shows the same advantages of traditional maglev wind turbines, but also improves the axial length utilization and decrease the cost of motor control.