scholarly journals Rectangular Closed Double Magnetic Circuit Offering Ultra-Long Stroke for Ultra-Low-Frequency Vibration Exciter

2020 ◽  
Vol 10 (17) ◽  
pp. 6118
Author(s):  
Junning Cui ◽  
Wei Li ◽  
Xingyuan Bian ◽  
Zhangqiang He ◽  
Limin Zou
Keyword(s):  
High Performance ◽  
Magnetic Circuit ◽  
Harmonic Distortion ◽  
Low Frequency ◽  
Fem Analysis ◽  
Magnetic Flux Density ◽  
Vibration Exciter ◽  
Low Frequency Vibration ◽  
Lumped Parameter ◽  
Long Stroke

High-performance magnetic circuit offering uniform magnetic flux density (MFD) along ultra-long stroke is the key to develop a vibration exciter for ultra-low-frequency (ULF) vibration calibration. In this paper, a rectangular closed double magnetic circuit (RCDMC) offering ultra-long stroke up to 1.2 m is modeled and optimized. In order to overcome the modeling difficulty arising from the long stroke, a high-accuracy theoretical model is established taking advantage of the structural symmetry of the RCDMC through lumped parameter magnetic equivalent circuit method. Matrix equations are derived based on Kirchhoff’s law and solved by iteration calculation to deal with the strong nonlinear characteristics of the yoke material. The deviations between the model and finite element method (FEM) analysis results are less than 1% for non-saturated yokes and ~10% for saturated yokes. Theoretically, an MFD up to 122 mT and an acceleration waveform harmonic distortion (AWHD) as low as 0.45% are achieved through model-based optimization. Experiments are carried out using an RCDMC prototype assembled in a horizontal vibration exciter. The experimental results show that an MFD of 102 mT and an AWHD of 0.27% along 1.2 m stroke are achieved, making the proposed RCDMC a solution for ULF vibration exciter.

scholarly journals Monocular vision-based low-frequency vibration calibration method with correction of the guideway bending in a long-stroke shaker

2019 ◽  
Vol 27 (11) ◽  
pp. 15968
Author(s):  
Ming Yang ◽  
Ying Wang ◽  
Chenguang Cai ◽  
Zhihua Liu ◽  
Haijiang Zhu ◽  
...  
Keyword(s):  
Low Frequency ◽  
Calibration Method ◽  
Monocular Vision ◽  
Low Frequency Vibration ◽  
Long Stroke

Vibration Rectification and Thermal Disturbances in Ultra Precision Inertial Sensors

2011 ◽  
Author(s):  
Curtis Zaiss ◽  
Swavik Spiewak
Keyword(s):  
High Performance ◽  
Nonlinear Distortion ◽  
Inertial Sensors ◽  
Angular Displacement ◽  
Angular Rate ◽  
Harmonic Distortion ◽  
Low Frequency ◽  
Displacement Sensors ◽  
Ultra Precision ◽  
On Line

Advanced inertial MEMS sensors facilitate achieving superb precision and resolution in measuring translational and rotational displacements, down to femtometers and milli-arcseconds. At present such performance is possible only in measurements of a very short duration, typically below 1 second. As this duration increases, the precision rapidly deteriorates. However, experimental accelerometers indicate the possibility of measurements with sub-micron precision for up to 30 seconds. For longer measurements, e.g., up to 5 minutes, the errors increase. However they still remain below 100 μm. The main cause of errors is a strong amplification of low frequency disturbances and distortions introduced by the sensors. It occurs when acceleration and angular rate are converted to the translational and angular displacement, i.e., during the integration. Thus, the key to maximizing the performance of inertial displacement sensors is a reduction of their low frequency disturbances. In the top tier sensors the key components of the disturbances include (1) the inherent thermodynamic and electrical noise, (2) chaotic mechanical phenomena, and (3) nonlinear distortion. The presented research is concerned with these three areas. It focuses on the identification and correction of errors which deteriorate a stability of the sensors’ bias, in particular on the vibration rectification error (VRE) and temperature variations due to the actuation in servo accelerometers. The investigated accelerometers are high performance sensors, digital and analog, whose total harmonic distortion is in the range from 1% down to a few parts-per-million (i.e., <0.001%). The objective is to develop on-line corrective filters capable of reducing the overall low frequency distortion below 0.00001%.

scholarly journals Design and Experiments of a Galloping-Based Wind Energy Harvester Using Quadruple Halbach Arrays

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6094
Author(s):  
Hai Dang Le ◽  
Soon-Duck Kwon
Keyword(s):  
High Performance ◽  
Low Frequency ◽  
Electrical Energy ◽  
Load Resistance ◽  
Field Analysis ◽  
Magnetic Flux Density ◽  
Original Design ◽  
Halbach Array ◽  
Magnetic Field Analysis ◽  
Halbach Arrays

This study aims to develop a device for harvesting electrical energy from low-speed natural wind. Four linear Halbach arrays are adopted to design a high-performance galloping harvester with the advantage of high durability and efficiency at low-frequency vibrations. The results of magnetic field analysis reveal that there are optimal sizes of the main and transit magnets of the Halbach arrays and coil to obtain the maximum magnetic flux density normal to the coil. The experimental and simulation results show that the electrical external load resistance significantly affects the vibration amplitude and the galloping onset velocity of the harvester. The results also reveal that the performance of the original design using the quadruple Halbach array was lower than that of the existing harvester because of the heavy magnet mass embedded in the tip prism. The modified design, reducing mass, improved the performance by four times compared to the original design.

scholarly journals SYNTHESIS OF THE LOW-FREQUENCY VIBRATION EXCITER

2021 ◽  
Vol 3 ◽  
pp. 66-71
Author(s):  
Dmitry Fedorov ◽  
Andrey Khitrov ◽  
Evgeny Veselkov ◽  
Yuliya Domracheva ◽  
Oksana Kozyreva
Keyword(s):  
Control System ◽  
Low Frequency ◽  
Magnetic Suspension ◽  
National Standard ◽  
Vibration Exciter ◽  
Magnetic Conductor ◽  
Low Frequencies ◽  
Modern Equipment ◽  
Mobile Part ◽  
Low Frequency Vibration

The article is devoted to synthesis of the low-frequency vibration exciter for checking of sensors of acceleration. In many areas of the modern equipment sensors of acceleration working in very low range of frequencies are widely used. For checking and graduation of such sensors the vibration exciter capable to provide rectilinear horizontal harmonic oscillations of the calibrated accelerometer in so low range of frequencies are required. Low frequencies of fluctuations cause the necessity of creation of big amplitudes of movements for ensuring the acceptable values of amplitudes of accelerations. The low-frequency electrodynamic vibration exciter with a magnetic suspension of mobile part which is a component of the National Standard of the vibration movement of the Russian Federation is so far created. However, development of the modern equipment demands expansion of frequency ranges to the area of ultralow frequencies. One of requirements shown to the vibration exciter working in the ultralow range of frequencies is increase in amplitude of horizontal movements of a mobile part as with small amplitudes the speed and acceleration of the harmonious law of the movements proportional according to the frequency of fluctuations and a square of this frequency, will have small amplitude values. One of problems of realization of a control system of the electric drive of the vibration exciter consists in that a mobile part possesses indifferent position of balance. The centre of fluctuations of a mobile part is not defined and can be in any point on magnetic conductor length. That fluctuations had the steady centre in an average point of a magnetic conductor without use of a mechanical spring, the drive is supplied with an additional control system of fluctuations, or a so-called electromagnetic spring.

Ultra-Low-Frequency Vibration Assisted Machining of Ti-6Al-4V Alloy

2016 ◽  
Vol 10 (4) ◽  
pp. 647-653 ◽  
Author(s):  
Tatsuya Sugihara ◽  
◽  
Toshiyuki Enomoto ◽  
Keyword(s):  
Titanium Alloys ◽  
High Performance ◽  
Low Frequency ◽  
Chemical Properties ◽  
High Temperature Strength ◽  
Dry Machining ◽  
Crater Wear ◽  
Vibration Period ◽  
Nc Program ◽  
Low Frequency Vibration

As titanium alloys such as Ti-6Al-4V provide several benefits, including high-temperature strength and high corrosion resistance, the demand for such materials has rapidly increased, particularly in the aircraft industries. On the other hand, they are known to be among the most difficult-to-cut materials due to their mechanical and chemical properties, which make tool life extremely short. In order to solve this problem, this paper proposes a new cutting method employing ultra-low-frequency (ULF) vibration. ULF vibration ranges from less than 1 Hz to approximately 10 Hz and is generated by using a numerically-controlled machine tool axis and an NC program. The results of turning experiments showed that the developed method significantly reduces crater wear in the machining of Ti-6Al-4V, even under dry machining conditions. Moreover, the mechanism that ULF vibration affects and the effect of actual cutting time and non-cutting time in each individual vibration period on the amount of crater wear were investigated. As a result, it was found that the developed process is a promising method for achieving high performance dry machining of titanium alloys.

Closed-Double-Magnetic Circuit for a Long-Stroke Horizontal Electromagnetic Vibration Exciter

2013 ◽  
Vol 49 (8) ◽  
pp. 4865-4872 ◽  
Author(s):  
Wen He ◽  
Chunyu Wang ◽  
Mei Yu ◽  
Runjie Shen ◽  
Shushi Jia
Keyword(s):  
Magnetic Circuit ◽  
Vibration Exciter ◽  
Electromagnetic Vibration ◽  
Long Stroke
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