Advanced Materials Research Vols. 655-657

Abstract: Using the basic finite element theory, 3D finite element models of flexible membranous disc coupling with different disc thickness is built by ANSYS ，and then the dynamic characteristics are analyzed in working conditions. In particular, the analysis of static stress and harmonic response to the thickness of 0.85 model is done for getting the stress variation under a rated condition. The date calculated by dynamic characteristics and stress analysis can satisfy the design requirements. Those researches and analysis provide a theoretical consideration for complex vibration situation of flexible membranous disc coupling and for the improvement and optimization of coupling product.

Abstract: Experiments on the durability for the rear driving axle were conducted in bench tests. By using time domain and frequency domain methods, the vibration and noise signals at bearings of driving axle were sampled and then analyzed. On the one hand, we find that the vibration level and noise level change with the wear of gears and bearings. On the other hand, with the development of the wear of gear and bearings, the frequency components of vibration and noise change with time. These experimental results will give help to further study of the durability and NVH characteristic of the rear driving axle.

Abstract: The present study considers the state-dependent delay differential equations (SD-DDEs) for the turning process. In general, series expansion of the SD-DDEs turning system is essential in the nonlinear analysis such as the conventional methods of multiple scales and harmonic balance. Unfortunately, the mathematical theory of SD-DDEs, especially for those with an implicit function of delay, was just recently developed and any rigorous mathematical theory has not yet been proven. As one approach for the nonlinear analysis of the SD-DDEs, physically reasonable results could be obtained by extending the general theory of DDEs to the SD-DDEs through the use of the series expansion in conjunction with the implicit function, although there still remains an open issue of its mathematical rigorousness. The other approach may be treating the original SD-DDEs directly. To this end, the high-dimensional harmonic balance (HDHB) analysis is performed in this study in order to investigate the nonlinear behaviors of the turning system in the form of SD-DDEs without its series expansion. The results obtained by HDHB analysis are validated by comparing results with those of direct time integration. Using the resulting bifurcation diagrams, nonlinear chatter behaviors of the turning system are examined and discussed.

Abstract: The satellite platform in the orbit, as the payload carrier, always suffers from the complex spatial dynamics disturbances. The disturbances affect the LOS stabilization of the high resolution optical payload and then affect the quality of the image from the high resolution earth observation system. In order to solve the problem, the vibration isolation technique-placing the appropriate vibration isolators between the vibration source and system to isolate the direct transmission of the vibration is adopted. In the paper, we take the two-axis isolator as the object of study, build its dynamic model and design the controller for the two-axis isolator. We use ADAMS which is used for the mechanical dynamics and MATLAB to do the combined simulation to verify the controller’s effects.

Abstract: Non-contacting gas film seal applies to the high speed working condition and a numerical method was presented for analyzing the effect of speed on the stability of cylinder gas film seal. The dynamics analysis model was established, solving the time-dependent Reynolds equation coupling with the dynamic equations. Through numerical simulation, the critical speed of cylinder gas film seal system and the diagram of critical mass versus rotor speed were obtained. The influence of the speed on dynamic stability was studied. The results show that the system stability becomes worse as rotor speed increases.

Abstract: Kane dynamics equations of metamorphic mechanism based on screw theory is built, and the constraint equation with cut-off joint is completed by introducing exponentials formula. The configuration-complete dynamics equations of metamorphic mechanism is established with this two equations combined. The configuration-complete dynamics equations of the metamorphic mechanism in cutting machine for complex-surface is built using this method.

Abstract: Considering the large structure and severe vibration for the present external parallel moving gear transmission, a kind of internal parallel moving gears transmission with compact and balance structure was designed. Working principle and structure were introduced. While the elastic deformation of all eccentric shafts, the elastic deformation of meshing gears, the elastic deformation of planetary bearing on eccentric shafts and supporting bearing on output shaft were considered, the elastic dynamic equation of the system was established by use of lumped mass method. The practical example and computer simulation was carried out and the dynamic characteristic was obtained. The results show that the gear meshing force and the load of planetary bearing become much steadier than traditional structure because of balance. This paper offers theoretical basis on correctly designing internal parallel moving gears transmission, reducing moving load and extending the service life.

Abstract: The increase of loss causes the temperature rise in motor, reducing the using life of spindle, which can seriously affect the performance of motor. Thus, accurate calculating of loss is meaningful to optimal design of electric spindle. In this paper, the losses both with load and without load were analyzed by time-step finite element method. As the result of simulation analysis, the spindle losses with load are higher than those without load. Comparison analysis indicates that losses are various with different load. And the load impacts on core loss mostly in ceramic spindle. In addition, in asynchronous ceramic spindle with 4N•m rated load, the core loss, solid loss and stranded loss are least when the load change from 1.8 N•m to 3.8N•m. Accordingly, the best operation condition under the influence of load in electric spindle is gained.

Abstract: The frequency-energy plot(FEP) of nonlinear vibration systems is a powerful tool for investigating the energy transfer phenomena related wiht the internal resonances occured in multi-digreeof- freedom(Multi-DOF) nonlinear vibration systems. In this paper, the modified Lindstedt-Poincare method is employed for constructing the FEP of a two-DOF nonlinear vibrating systems. First, the original vibartion equations are modified for the application of the modified Linstedt-Poincaré method. Then, by using the modified Linstedt-Poincaé method, the nonlinear normal modes(NNMs) of the system are obtained. Finally, the frequency-energy plot of the system is constructed analytically. Numerical results show that the method adopted in this paper is effective and accurate.

Abstract: The automatic ball balancer is equipment used to balance the rotor system online and control its forced vibration. Although the rotor system is a nonlinear system actually, especially the occurrence of the nonlinear elastic restoring force in the support of rolling elements bearings, many researches still focus on the linear rotor systems at present. The Jeffcott rotor acted by unsymmetrical nonlinear restoring force is studied in this paper. Through the resolving theoretically and simulating numerically, the principal resonance respond of the rotor system controlled by the balancer with two balls and its stability are studied, while the vibration characteristics and movement laws of the rotor and balls in every rotary speed region are analyzed. The results showed that the balancer can suppress the principal vibration of the nonlinear rotor system in high speed region very well.