Papers by Keyword: Vibration Frequency

Abstract: The processing of materials with a hardness greater than 55 HRC has always required the use of unconventional or grinding methods in order to obtain the quality and precision required by the technical conditions. For these reasons, the researches of the last decades have developed an unconventional method of processing, with great precision and precision, by assisting the classic processing techniques, with forced, unamortized, low amplitude ultrasonic vibrations. The present paper presents the results of some researches regarding the processing of extradural materials, by the assisted realization of the non-cushioned, low amplitude ultrasonic vibrations. It is demonstrated that this method of processing can obtain very fine surfaces, sometimes being able to replace the grinding, with much lower costs, in terms of energy consumption and tool wear.

Abstract: This paper study on the influence of ultrasonic vibration assisted grinding (UAG) process on surface topography and properties of C/SiC composites. Through the surface quality experiments of common grinding (CG) and UAG, the height distribution parameters and function parameters are obtained and used to analyze the characteristics of the material surface topography. The relationship between grinding process and the composites surface quality is pointed out by experimental research. The orthogonal design is employed to optimize ultrasonic parameters and grinding parameters. The optimized condition is carried out to modify the surface quality. The results show that ultrasonic vibration has a great influence on height and surface bearing properties; the surface roughness is improved by the small vibration amplitude and low frequency. The grinding depth is the key factor on surface topography modification and the feed rate is the second. According to the research, an important technical support is carried out to improve the surface performance of C/SiC composites.

Abstract: Ceria stabilized zirconia microspheres of about 150 microns were prepared by external gelation. The effect of vibration frequency on jet droplet dispersion and size uniformity was investigated. The diameter variances of microspheres prepared at frequency range of 1300 to 2300 Hz were calculated. The optimal frequency was found to be in good accordance with Raleigh’s theory. The obtained microspheres under optimal frequency were characterized by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The data showed their good size uniformity, smooth surface, compactness, and good CSZ phase.

Abstract: In this article, impact of cross-section and size on vibration of silicon nanowires is simulated by the molecular dynamics method based on molecular dynamics software Material Studio. The comparison of fundamental frequencies of the silicon nanowires with triangle, diamond, and hexagon cross sections is carried out. The orientations of these silicon nanowires are all in <111> direction. Then we change the length and the width of silicon nanowires to investigate the impact of size on vibration of silicon nanowires. The results show that with the influence of surface effect, the vibration frequency of silicon nanowires strongly depends on cross-section and size.

Abstract: The directional well drilling technology is extensively utilized and developed throughout the world. However, series of drilling problems occurred in the operation process of directional drilling. In order to reduce the friction of drilling tools, an oscillation tool with a fluidic amplifier has been field tested, and the pressure pulse of oscillation tool has been obtained. Field test results have shown that the oscillation tool has an extensive flexibility to directional well drilling, and the oscillation tool could stably actuate the drilling tool to have reciprocating vibration, which contributes to the friction and drag reduction of drilling tools. Furthermore, it can be concluded that the pressure pulse value generated by pumped fluid varies with input flow rate, and the pressure of oscillation tool increases while the flow rate is increasing. In addition, the motion frequency of the oscillation tool is exponentially increasing with the raise of pumped flow rate.

Abstract: It will vibrate when the natural frequency close to the external exciting force during the operation of the motor, accurate and effective calculation of the natural frequency of the motor has an important significance to damping noise. The inherent frequencies of the motor were got by numerical simulation model and the ANSYS finite element modal analysis, and comparison results verify the effectiveness of the motor model. The effect of the foot length change to the inherent frequency was researched emphasis, and puts forward related suggestions.

Abstract: In this paper, the defect sheet was captured coincidentally. According to the defective product’s characteristics, we suspected to be caused by the vertical vibration of the roll. When the rolling speed reached a certain value, the vibration of the fourth stand can be feel. The experiment of the vibration data collection was taken to compare the vibration parameters of rolling operating side with those of drive side by wavelet analysis. The result states that the abnormal vibration signal features can be extracted in a special frequency segment of wavelet decomposition, and the vibration frequency to the roll is confirmed which appeared product defects.

Abstract: In order to improve the accuracy of cable tension test, the motionequation of the stay cable with the rubber damper was established bases on the principleof Hamilton. First, the correction method for the damping coefficient of rubberdamper and cable tension was proposed according to the higher modal frequencyand measured frequency of cables difference. Then, take the cable of DongtingLake Bridge as an example, the cable tension was calculated by the proposedmethod and compared with the results of measurement by frequency method.Results showed that the proposed method can improve the accuracy of cabletension test and can effectively evaluate the cable tension condition of thecable-stayed bridge.

Abstract: To assess the carrying capacity and reliability of the-Longtan Bridge, applied static load in the middle of the bridge step by step, then collected strain and deflection data of the beam. In order to understand the working principle of a bridge under dynamic loads, dynamic load test - Vehicle traffic test and fluctuation test t was performed, and vibration frequency data was collected. This paper described the basic principles of the bridge static and dynamic tests, and introduced the program of the experiment. Based on the test data, the static and dynamic mechanism of the bridge was discussed, the conclusion provides the basis for further study of bridge mechanism of the mechanical.

Abstract: Based on the finite element theory, an analysis about the changing of rotor vibration mode of the wind turbine with and without rudder at static state, and a research was carried out to study the impact of the rudder on wind turbine vibration frequency during operation condition of a small horizontal axis wind turbine by using Ansys Workbench. The result showed that, rudder vibration mode was the coupling of rudder vibration mode and first order anti-symmetric vibration mode of rotor. With the increasing of rotating speed, wind turbine vibration frequency increased because of the stiffening effect caused by centrifugal force, and the difference of first order anti-symmetric vibration frequency and symmetric vibration frequency was decrease which was caused by the aerodynamic force. At the same time, the changing of the external load had no effect on the vibration frequency of rudder, the reason of that was counterweight of the rudder. When the rotor speed was in the resonance region, rudder vibration frequency was equal to first order anti-symmetric vibration frequency at the rotating speed n=10.91Hz, an obviously resonance phenomenon occurred. The related research could provide some theoretical guidance for the design of small wind turbine rudder.