Research On Electromagnetic Vibration Absorber With Variable Damping

This paper presents a tunable electromagnetic damping semi-active vibration absorber,which with the character of adjustment of stiffness and damping within a certain range.Adjustment of stiffness is achieved by changing the current of electromagnet, and adjustmentof damping is achieved by changing the underwater sectional area of damper. So the naturalfrequency is changed and the absorber band is broadened, in this condition, we could studyabsorber’s working situation with different stiffness and damping.The study is based on electromagnetic theory, calculating the magnetic field distributionbetween electromagnets and permanent magnet by numerical calculation, and then wesimulate the absorber’s magnetic properties by ANSOFT software. After comparing thesimulation results with experimentally measured results, we obtain that all of errors are lessthan20%, which means the ANSOFT results can be used as references. Then, theelectromagnetic absorber bench is designed and established. From the study of suppressionproperties, we get absorber effect from7dB to22dB under the frequency from5.5Hz to8Hz,which represents a good performance. As the magnetic stiffness of variable and invariable cancancel each other out, there is little effect towards absorber characteristics from distance of airgap. This can provide some basis for structural design.A damper is processed, on the basis of absorber. It is shown that the damping ratio can bechanged with different liquid viscosity and underwater sectional area. When the medium isglycerol, the damping ratio can be adjusted from0.04to0.109. Finally, the absorb characterunder different damping ratio is studied, and then it is compared with simulating results toverify the correctness of the simulation...