With many features,the magnetorheological fluid( MRF) damper is widely applied in the semiactive vibration control system. And sensitivity analysis is an important method to study the influence weight of various param...With many features,the magnetorheological fluid( MRF) damper is widely applied in the semiactive vibration control system. And sensitivity analysis is an important method to study the influence weight of various parameters on damping force characteristics. A mathematical model of the output damping force on the MRF damper is established by the mechanism modeling method,a first order output sensitivity equation is deduced and the expression of the first order output sensitivity function is obtained. The first-order sensitivity functions of ten design parameters are solved,and the influence degree of system parameters change on the output force of MRF damper is analyzed by comparing the sensitivity index of the parameters. Two sensitivities of vibration velocity and control current are obtained through experiment to prove the other parameters sensitivity analysis conclusion by analogy verification,which provides guidance for the structure optimization design of MRF damper.展开更多
Rare earth permanent magnet nanostructures have attracted intensive interest recently due to the increasing demand for integrated and miniaturized devices.As a typical example,hard magnetic Nd_(2)Fe_(14)B-based nanost...Rare earth permanent magnet nanostructures have attracted intensive interest recently due to the increasing demand for integrated and miniaturized devices.As a typical example,hard magnetic Nd_(2)Fe_(14)B-based nanostructures with desired coercivity have been developed by a reduction–diffusion process and the Nd-rich phase is supposed to be essential to optimize the magnetic properties,whereas the identification and role of the Nd-rich phase have not been addressed so far.Herein,Nd_(2)Fe_(14)B-based nanostructures with different Nd-rich phase contents,Nd_(15)Fe_(77)B_(8) and Nd_(14.2)Fe_(78.6)B_(7.2),are rationally prepared by a reduction–diffusion process.The coercivity of Nd_(15)Fe_(77)B_(8) can reach 5 kOe,which is higher than that of Nd_(14.2)Fe_(78.6)B_(7.2) of 3.2 kOe.First-order-reversal-curve (FORC) analysis confirms the amorphous paramagnetic Nd-rich phase as pinning centers and reveals magnetic interactions and magnetic domain nature in the two nanostructures.The increase of the Nd-rich phase optimizes microstructures and magnetic interactions,responsible for higher coercivity.This work points out the relationship between the Nd-rich phase,magnetic interactions,microstructures,and magnetic properties,and could usher in new ways of fabricating advanced permanent magnetic nanostructures.展开更多
基金Supported by the National Natural Science Foundation of China(No.51375423,51505410)the National Key Basic Research Program(No.2014CB046400)
文摘With many features,the magnetorheological fluid( MRF) damper is widely applied in the semiactive vibration control system. And sensitivity analysis is an important method to study the influence weight of various parameters on damping force characteristics. A mathematical model of the output damping force on the MRF damper is established by the mechanism modeling method,a first order output sensitivity equation is deduced and the expression of the first order output sensitivity function is obtained. The first-order sensitivity functions of ten design parameters are solved,and the influence degree of system parameters change on the output force of MRF damper is analyzed by comparing the sensitivity index of the parameters. Two sensitivities of vibration velocity and control current are obtained through experiment to prove the other parameters sensitivity analysis conclusion by analogy verification,which provides guidance for the structure optimization design of MRF damper.
基金supported by the National Natural Science Foundation of China(51590882,51631001 and 51672010)the National Key R&D Program of China(2017YFA0206301).
文摘Rare earth permanent magnet nanostructures have attracted intensive interest recently due to the increasing demand for integrated and miniaturized devices.As a typical example,hard magnetic Nd_(2)Fe_(14)B-based nanostructures with desired coercivity have been developed by a reduction–diffusion process and the Nd-rich phase is supposed to be essential to optimize the magnetic properties,whereas the identification and role of the Nd-rich phase have not been addressed so far.Herein,Nd_(2)Fe_(14)B-based nanostructures with different Nd-rich phase contents,Nd_(15)Fe_(77)B_(8) and Nd_(14.2)Fe_(78.6)B_(7.2),are rationally prepared by a reduction–diffusion process.The coercivity of Nd_(15)Fe_(77)B_(8) can reach 5 kOe,which is higher than that of Nd_(14.2)Fe_(78.6)B_(7.2) of 3.2 kOe.First-order-reversal-curve (FORC) analysis confirms the amorphous paramagnetic Nd-rich phase as pinning centers and reveals magnetic interactions and magnetic domain nature in the two nanostructures.The increase of the Nd-rich phase optimizes microstructures and magnetic interactions,responsible for higher coercivity.This work points out the relationship between the Nd-rich phase,magnetic interactions,microstructures,and magnetic properties,and could usher in new ways of fabricating advanced permanent magnetic nanostructures.
