Advanced Materials Research Vols. 139-141

Abstract: CSP rolling mill abnormal vibration problem is one of the worldwide difficult problems in rolling fields. In this article, using the modern acceleration telemetry system, an integrated test is taken to the rolling mill vibration and the laws of the mill vibration are captured. The test shows that there is severe horizontal vibration of roll system, especially the work rolls, at the same time, there are also abnormal vibration occurs on AGC (automatic gauge control). In order to reveal the internal links between the vertical vibration of AGC and horizontal vibration of the roll system, using the harmonic analysis module and the transient response analysis module of ANSYS software, through simulation study to research the impact of the vertical vibration of AGC on the horizontal vibration of the roll system and meaningful conclusions are clarified.

Abstract: Shield tunneling machine(STM) is a safety and high-efficiency excavator in the subway tunnel project, but the dynamics of whose multi-stage planetary gearbox is still a critical issue. In this paper, the torsional dynamic model for three-stage planetary gears train(PGT) is developed by lumped parameter method. According to the configuration and design parameters of the planetary gearbox, the natural frequencies are calculated, and the vibration modes are also analyzed. The natural modes can be classified into one of the three categories: rigid-body mode, distinct modes and planet modes. By using finite element(FE) method, the vibration characteristics of gearbox housing are also computed and analyzed for lucubrating vibration transfer and coupling between planetary gears train and housing, which is the important foundation for dynamic optimization of planetary gearbox.

Abstract: To overcome the limit on the natural resonant frequency and bandwidth of the traditional single-axis servo system, the paper designed a double-axis compound servo system, and established the transfer function of the fast reflector, camera, D/A data acquisition card and velocity servo unit, and further obtained the transfer function and theory model of this servo system. By combining simulation, it analyzed the influence of the dynamic hysteresis error, flat vibration error, centroid detection error, mechanical torque distortion error on the accuracy of the system. It proposes the view that the modern synthesize algorithm can optimize and compensate the parameter of the fast reflector system, by this method designed robust controller can restrain the remaining low frequency distortion and high frequency noise of the system, and further improve the bandwidth and accuracy of the system. The experiment shows that the compound-axis servo system bandwidth is of 2-16Hz and system accuracy of 0.8-4μrad.The experimental results and theory analysis are compatible basically. The design provides a foundation for the study on the servo system in the fields of the space optical communication system, deep space detection, remote sensing and etc

Abstract: The LMS Test.Lab system was used to carried out experimental modal analysis of large vibratory feeder, the PloyMAX method was employed to estimate and identify the modal parameter of vibratory feeder and the modal parameters such as modal frequencies, modal damping ratios and mode shape at concerned band were got; Compared the results of experimental modal analysis to the results of finite element method, the results show that the experimental modal analysis and finite element analysis was consistent to some extent, verified the correctness of finite element model; the bias between experimental and theoretical is inevitable, the experimental results are more reliable relative to the actual and better reflect the dynamic characteristics of vibratory feeder, which will be provided as the reference for dynamic design and dynamic improvement of the vibratory feeder.

Abstract: Among various non-smooth dynamic systems, the periodically forced oscillation system with impact is the most common in engineering applications. The dynamics becomes complicate due to the impact against the stops. This paper presented a systematic study on the periodically forced oscillation system with impact. In particular, impulsive differential equation, Poincare map is applied. The proposed model has high numerical accuracy in describing their dynamics. It helps to optimize the design of a commercial product.

Abstract: Satellite calibration antenna suffered rigorous vibration environment in the course of lunching. Random vibration is being specified for acceptance tests by spacecraft structure. The waveguide tube of antenna was cracked in the random vibration test. Fracture analysis using scanning electron microscopic showed that failure were induced by fatigue damage. Finite element model of antenna was built and root mean square (rms) stress of waveguide tube was obtained in random vibration analysis. The maximum rms stress was 35.6MPa and located at the flange base. Then fatigue life of waveguide tube was estimated, using the Palgren-Miner rule and the three-band method. The estimated fatigue life of 109 seconds showed the waveguide tube couldn’t ensure safety during 120 seconds of the random vibration. Finally two ribs were added at each flange base for decreasing the stress concentration. The fatigue life of improved waveguide tube was 811 seconds. Then it passed the random vibration test.

Abstract: The pressure pulsations inner the hydraulic power pipelines not only deteriorate the precision of execution unit, but also bring on vibration, noise or other troubles in hydraulic device. In this paper, the output pressure pulsations were treaded as a stationary random process approximately. The mean square deviation of dynamic stress under the pumping source white noise exciting was calculated based on frequency responses. The first-passage failure criterion and fatigue damage accumulation failure criterion were adopted to analyze the dynamic pressure reliability respectively, and the relation of amplitude pulsations and the pipelines reliability was obtained. The results indicated that the preventative design method of below10% of rated pressure did not meet the security specification of the hydraulic power unit.

Abstract: According to the characteristics of floating cranes, an affordable numerical method to model the floating cranes and the external excitations such as wind, wave and shimmy loads was proposed. Local coordinates modifying wind, wave and shimmy loads which are determined separately were combined in the global coordinate system according to the geometric positions. The spectra of wind loads and wave loads were converted into time domain separately according to the linear method, while a shimmy load is determined according to the Lagrange’s Equation. As an example, the external excitation caused by random wind, wave and shimmy loads on a 7500-ton giant floating crane were simulated, and the transient dynamic response was predicted and discussed. Focusing on the characteristics of structure of floating cranes, the research indicates that the dominant frequency of the wave load is low, as compared to wind and shimmy loads, and that the shimmy load is closely related to the environmental excitations such as wind and wave loads. The results also suggest that the transient response of the crane is mainly related to the shimmy load.

Abstract: X-axis and Y-axis workbenches are important parts of PCB drilling machine. Theirs dynamic properties directly affect the overall performance of drilling machine. Modal analysis method was adopted in this paper. Measurement and analysis on vibration of X-axis and Y-axis workbenches based on LMS Test. Lab was carried out. The modal parameters such as natural frequency, damping ratio and corresponding vibration modes were obtained. The results present that the X-axis and Y-axis workbenches have a high fundamental frequency, which is 564Hz and 1014Hz respectively. And the damping ratio is less than 4.91% and 2.99%, which shows that the stiffness of the X-axis and Y-axis workbenches are higher. The FEM modal analysis shows that it has the similar results with the experiments in modal parameters. The analysis of natural characteristics of workbench provides guidance for optimizing machining parameters of drilling and improving structure of workbench.

Abstract: The amorphous alloy dry-type transformer is one type of new energy-saving transformer. With the rapid development of amorphous alloy dry-type transformers, its vibration and noise also draws increasing attention. In this paper, the experiments of the amorphous alloy transformer core were carried out by vibration test systems. The influences of vibration in amorphous alloy transformer core under different support situation are analyzed. The influences of the winding under different sides and the Number of Windings are studied. It is shown that the boundary support has a greater impact on vibration of the core. The vibration of the core may be damped by exerting some restraint, especially in vertical direction. The different winding sides and the number of winding turns have little effect on the vibration of the core. The results presented in this paper can guide the application of the vibration and noise control of the amorphous alloy dry-type transformer.