Applied Mechanics and Materials Vols. 433-435

Abstract: As the executive component of CNC machine tools feed movement and auxiliary motion, feed system plays an important part in ensuring the positioning accuracy, sensitivity and stability. By taking single-screw-drive feed system and double-screw-drive feed system of CNC as the object of study, two-degree-of-freedom vibration models of them are established to analyze the dynamic characteristics, and further calculate modal vibration modes and natural frequencies. The finite element analysis models of the two systems are also established, concerning the influence of joint surface, vibration modes and natural frequencies are obtained by means of modal analysis. By comparing the simulation results and the calculated data, the feed systems vibration modes and natural frequencies can be accurately calculated by the proposed vibration models, and the relative errors of corresponding vibration frequencies are controlled within 15%.

Abstract: With the Synchronous Dual Ball Screw Feeding System used in a Milling-Turning compound machining center as the research object. For study the ball screw vibration modal, which using Lagrange established the dynamics equation and using the Lizs series expansion analyzing its various order modal coupling characteristics. Meanwhile using the ANSYS analysis to get the first three order vibration mode diagram and calculate the frequency corresponding to the critical speed for each rank. Through the analysis found that the screw pitch determine the modal coupling axial and corner, the workbench position and load quality changes, the screw vibration frequency also changes. Provide theoretical analysis for the analysis of dynamic characteristics of the next step.

Abstract: Electrolytic aluminium pre-baked anode conductive device for the special friction Welder upsetting system is the research object. Establish dynamic equation of the upsetting system by its Lagrange equation; analyze the key factors affecting the systems dynamic characteristics; build the systems finite element model to be real by ANSYS Workbench; Set key parameters for the two sets of plans and do analysis for the modal and harmonic response successively. The two plans compared results reveals that the guide spacing and the damping among all the parts can affect the systems dynamic characteristics, which will provide a basis for further improvement and optimization of special friction welding machine bed.

Abstract: Power split device (PSD) affects the power performance and control strategy of hybrid electric vehicle (HEV). In this paper, a new threshold function for wavelet denoising is used to reduce noise in test torque and rotational speed data. The dynamic simulation is carried out at the moment of planetary gear shaft (PGS) failure, after the rigid-flexible coupled model of PSD is established. According to the obtained stress of PGS, analysis of PGS fracture is verified.

Abstract: In this paper, the dynamical behaviors of the centrifugal flywheel governor with external disturbance is studied and it has abundant nonlinear behavior.The influence of system parameter is discussed by Lyapunov exponents spectrum and global bifurcation diagram, which accurately portray the partial dynamic behavior of the centrifugal flywheel governor. The routes to chaos are analyzed using Poincaré sections, which are found to be more complex . Periodic and chaotic motions can be clearly distinguished by Poincaré sections, bifurcation diagrams and Lyapunov exponents. Then, the paper proposes coupledfeedback control and adaptive control methods to achieve the chaotic the centrifugal flywheel governor system synchronization, the numerical simulation was provided in order to show the effectiveness of coupled feedback control and adaptive control methods for the synchronization of the chaotic nonautonomous centrifugal flywheel governor system.

Abstract: In order to solve one of the main negative effects of in-wheel driving system, caused by heavy unsprung mass, a new kind of design is put forward: in which in-wheel motor is used not only as a driving part, but also as a mass element in a dynamic vibration absorber. By changing motor from unsprung mass into sprung mass, the dynamic vibration absorber is no longer constrained by in-wheel space and vehicle mass. Due to the reduction of unsprung mass, vertical performance of vehicle, especially wheel ground adhesion is improved. An efficiency, compact and reliable system is designed in the paper.

Abstract: As commonly supporting parts of the spindle and the feed systems on the high-end grade CNC machine tool, dynamic characteristic of angular contact ball bearings had been a research hot spot in the current. Aiming at solving the problem that obtained the dynamic stiffness and damping of angular contact ball bearings, the factors of joint surfaces dynamic characteristic were equivalently viewed as a kind of virtual material in the paper, and an equivalent model of dynamic parameters for bearings joint surfaces was proposed based on the virtual material; an experimental device was developed to test the bearings dynamic parameters. The comparison of experimental results and simulation results showed that modal parameters of bearings could be accurately analyzed by the proposed modeling approach, and the relative errors of corresponding vibration frequencies in the radial and the axial directions could be controlled within 7%.

Abstract: In the designing of the straight line conjugate internal meshing gear pump, it is very important for us to analyze its flow field performance. In this paper, FLUEN is utilized to analyze its flow field which bases on moving grid computing ,the paper can get factors that structure impacts on performance. The work provides reference and a certain theory foundation for optimization of the gear pump and straight line conjugate internal meshing gear pump will be widely used in engineering machinery.

Abstract: This paper gives a perturbation theorem for frames in a Hilbert space which is a generalization of a result by Ping Zhao. It is proved that the condition a linear operator is invertible can be weakened to be surjective, and a similar result also be obtained for a Riesz basis. The perturbation theorems for frames and Riesz bases in a Hilbert space were studied by operator theory in functional analysis.