Controllability of a Magnetorheological Fluid Squeeze Film Damper under Sinusoidal Magnetic Field

2007 ◽  
Vol 334-335 ◽  
pp. 1089-1092 ◽  
Author(s):  
Chang Sheng Zhu
Keyword(s):  
Magnetic Field ◽  
Squeeze Film ◽  
Field Frequency ◽  
Mr Fluid ◽  
Magnetic Field Frequency ◽  
Squeeze Film Damper ◽  
Fluid Damper ◽  
Sinusoidal Magnetic Field ◽  
Mr Fluid Damper ◽  
The Magnetic Field

The controllability of a magnetorheological(MR) fluid squeeze film damper under a sinusoidal magnetic field was experimentally studied on a flexible rotor. It is shown that the frequency of the excitation magnetic field has a great effect on the controllability of the MR fluid damper. As the magnetic field frequency increases, the controllability of the MR fluid damper significantly reduces. There is a maximum frequency of the magnetic field for a given magnetic field strength or a minimum strength of the magnetic field for a given magnetic field frequency to make the dynamic behavior of the MR damper be controllable. When the magnetic field frequency is over the maximum one or the magnetic field strength is less than the minimum one, the controllability of the MR fluid damper almost completely disappears and the dynamic behavior of the MR fluid damper with the sinusoidal magnetic field is the same as that without the magnetic field.

scholarly journals Hall-Effect Sensor Technique for No Induced Voltage in AC Magnetic Field Measurements Without Current Spinning

2021 ◽  
Author(s):  
Anand Lalwani ◽  
Ananth Saran Yalamarthy ◽  
Debbie Senesky ◽  
Maximillian Holliday ◽  
Hannah Alpert
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Hall Effect ◽  
Induced Voltage ◽  
Field Frequency ◽  
Magnetic Field Frequency ◽  
Ac Magnetic Field ◽  
Hall Effect Sensor ◽  
Offset Voltage ◽  
The Magnetic Field

Accurately sensing AC magnetic field signatures poses a series of challenges to commonly used Hall-effect sensors. In particular, induced voltage and lack of high-frequency spinning methods are bottlenecks in the measurement of AC magnetic fields. We describe a magnetic field measurement technique that can be implemented in two ways: 1) the current driving the Hall-effect sensor is oscillating at the same frequency as the magnetic field, and the signal is measured at the second harmonic of the magnetic field frequency, and 2) the frequency of the driving current is preset, and the measured frequency is the magnetic field frequency plus the frequency of the current. This method has potential advantages over traditional means of measuring AC magnetic fields used in power systems (e.g., motors, inverters), as it can reduce the components needed (subsequently reducing the overall cost and size) and is not frequency bandwidth limited by current spinning. The sensing technique produces no induced voltage and results in a low offset, thus preserving accuracy and precision in measurements. Experimentally, we have shown offset voltage values between 8 and 27 μT at frequencies ranging from 100 Hz to 1 kHz, validating the potential of this technique in both cases

scholarly journals Hall-Effect Sensor Technique for No Induced Voltage in AC Magnetic Field Measurements Without Current Spinning

2021 ◽  
Author(s):  
Anand Lalwani ◽  
Ananth Saran Yalamarthy ◽  
Debbie Senesky ◽  
Maximillian Holliday ◽  
Hannah Alpert
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Hall Effect ◽  
Induced Voltage ◽  
Field Frequency ◽  
Magnetic Field Frequency ◽  
Ac Magnetic Field ◽  
Hall Effect Sensor ◽  
Offset Voltage ◽  
The Magnetic Field

Accurately sensing AC magnetic field signatures poses a series of challenges to commonly used Hall-effect sensors. In particular, induced voltage and lack of high-frequency spinning methods are bottlenecks in the measurement of AC magnetic fields. We describe a magnetic field measurement technique that can be implemented in two ways: 1) the current driving the Hall-effect sensor is oscillating at the same frequency as the magnetic field, and the signal is measured at the second harmonic of the magnetic field frequency, and 2) the frequency of the driving current is preset, and the measured frequency is the magnetic field frequency plus the frequency of the current. This method has potential advantages over traditional means of measuring AC magnetic fields used in power systems (e.g., motors, inverters), as it can reduce the components needed (subsequently reducing the overall cost and size) and is not frequency bandwidth limited by current spinning. The sensing technique produces no induced voltage and results in a low offset, thus preserving accuracy and precision in measurements. Experimentally, we have shown offset voltage values between 8 and 27 μT at frequencies ranging from 100 Hz to 1 kHz, validating the potential of this technique in both cases

scholarly journals Analysis of a Compact Squeeze Film Damper with Magneto Rheological Fluid

2020 ◽  
Vol 70 (2) ◽  
pp. 122-130
Author(s):  
Rahul Kumar Singh ◽  
Mayank Tiwari ◽  
Anpeksh Ambreesh Saksena ◽  
Aman Srivastava
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Squeeze Film ◽  
Vibration Level ◽  
Mr Fluid ◽  
Squeeze Film Damper ◽  
Rotor Systems ◽  
Jeffcott Rotor ◽  
Magneto Rheological ◽  
Control Feedback

Rotor systems play vital role in many modern day machinery such as turbines, pumps, aeroengines, gyroscopes, to name a few. Due to unavoidable unbalance in the rotor systems, there are lateral and torsional vibrations. Ignoring these effects may cause the system serious damages, which sometimes lead to catastrophic failures. Vibration level in rotor systems is acceptable within a range. Focus in this work is to minimize the vibration level to the acceptable range. One of the ways vibration level can be minimised is by means of providing damping. To accomplish this task in this work a new concept squeeze film damper is made by electro discharge machining which is compact in configuration, is filled with magneto-rheological (MR) fluid and tested out on one support of a Jeffcott rotor. This compact squeeze film damper (SFD) produces damping in a compact volume of the device compared to a conventional SFD. MR fluid is a smart fluid, for which apparent viscosity changes with the application of external magnetic field. This compact damper with MR fluid provides the variable damping force, controlled by an external magnetic field. In this work, proportional controller has been used for providing the control feedback. This MR damper is seen to reduce vibrations in steady state and transient input to the Jeffcott rotor. Parametric study for important design parameters has been done with the help of the simulation model. These controlled dampers can be used for reducing vibrations under different operating conditions and also crossing critical speed.

RESONANT MAGNETOELECTRIC EFFECTS IN Ni/Pb(Zr,Ti)O3/FeCo TRILAYERED SEMICIRCULAR COMPOSITES

2013 ◽  
Vol 20 (01) ◽  
pp. 1350004 ◽  
Author(s):  
H. HONG ◽  
Y. G. WANG ◽  
K. BI ◽  
F. G. CHEN
Keyword(s):  
Magnetic Field ◽  
Field Frequency ◽  
Zero Bias ◽  
Resonant Frequencies ◽  
Magnetoelectric Effects ◽  
Magnetic Field Frequency ◽  
Voltage Coefficient ◽  
The Magnetic Field ◽  
Effective Excitation ◽  
Multifunctional Devices

Magnetoelectric (ME) effect has been studied in semicircular composites with a negative magnetostrictive/piezoelectric/positive magnetostrictive Ni/Pb(Zr,Ti)O3/FeCo trilayered structure. The ME behavior of the Ni/Pb(Zr,Ti)O3/FeCo is different from those in previous studies and zero-bias ME effects and four remarkable resonant peaks have been observed in the dependence of the ME voltage coefficient on the magnetic field frequency in the 1–150 kHz range. The effective excitation of the acoustical oscillations provided by the positive and negative magnetostrictive layers is responsible for the multifrequency ME effects. The results open up a suitable way to make multifunctional devices with multi-resonant-frequencies and/or zero-bias operations.

Study of the Vibration Control of a Rotor System Using a Magnetorheological Fluid Damper

2005 ◽  
Vol 11 (2) ◽  
pp. 263-276 ◽  
Author(s):  
J. Wang ◽  
G. Meng
Keyword(s):  
Magnetic Field ◽  
Vibration Control ◽  
Control Method ◽  
Rotor System ◽  
Shear Mode ◽  
Rotor Vibration ◽  
Mr Fluid ◽  
Critical Speeds ◽  
Fluid Damper ◽  
Mr Fluid Damper

A shear mode magnetorheological (MR) fluid damper used for rotor vibration control is designed and manufactured, and the theoretical model of a cantilevered rotor system with the MR fluid damper is established. The response properties of the rotor system are studied theoretically and experimentally. It is found from the study that the Coulomb friction of the damper is increased as the magnetic field strength applied to the MR fluid increases. As a result, the vibration amplitude of the rotor system supported by the MR damper is decreased near the undamped critical speeds, but is increased in a rotating speed range between the first and the second undamped critical speeds. At the same time, the damped critical speed of the rotor system is increased with the increase of the applied magnetic field. Based on these characteristics, a simple on-off control method is used to suppress the rotor vibration across the critical speeds, and the results show that the method is very effective.

scholarly journals Design of a New 1D Halbach Magnet Array with Good Sinusoidal Magnetic Field by Analyzing the Curved Surface

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2522
Author(s):  
Guangdou Liu ◽  
Shiqin Hou ◽  
Xingping Xu ◽  
Wensheng Xiao
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Permanent Magnet ◽  
Flux Density ◽  
Permanent Magnets ◽  
Air Gap ◽  
Curved Surface ◽  
Magnetic Flux Density ◽  
Sinusoidal Magnetic Field ◽  
The Magnetic Field

In the linear and planar motors, the 1D Halbach magnet array is extensively used. The sinusoidal property of the magnetic field deteriorates by analyzing the magnetic field at a small air gap. Therefore, a new 1D Halbach magnet array is proposed, in which the permanent magnet with a curved surface is applied. Based on the superposition of principle and Fourier series, the magnetic flux density distribution is derived. The optimized curved surface is obtained and fitted by a polynomial. The sinusoidal magnetic field is verified by comparing it with the magnetic flux density of the finite element model. Through the analysis of different dimensions of the permanent magnet array, the optimization result has good applicability. The force ripple can be significantly reduced by the new magnet array. The effect on the mass and air gap is investigated compared with a conventional magnet array with rectangular permanent magnets. In conclusion, the new magnet array design has the scalability to be extended to various sizes of motor and is especially suitable for small air gap applications.

Experimental Investigation on Dynamic Characteristics of Magneto-Rheological Fluid Suspension through on Road Comfort Testing

2015 ◽  
Vol 772 ◽  
pp. 373-377
Author(s):  
K.G. Saravanan ◽  
N. Mohanasundara Raju
Keyword(s):  
Experimental Investigation ◽  
Ride Comfort ◽  
Vehicle Dynamic ◽  
Dynamic Approach ◽  
Mr Fluid ◽  
Road Profile ◽  
Fluid Damper ◽  
Magneto Rheological ◽  
Active Damper ◽  
Mr Fluid Damper

The present study deals with the application of the Magneto-Rheological (MR) fluid assisted semi-active damper as a replacement to the conventional suspension system in Maruti 800 car (source vehicle). MR fluid damper is designed, fabricated and automated with a microcontroller. This experimentation is carried out with real time instrumentation on the selected road profile as a vehicle dynamic approach. Results obtained from the travel imply that MR fluid suspension suppresses the vibrations more effectively than the existing passive damper system. The MR fluid dampens the acceleration and displacement of the piston to a greater extent thereby controlling the ride comfort.

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