计及漏磁的堆栈式超磁致伸缩制动器多物理场耦合建模研究

Multi-Physics Modeling Research of Stacked Giant Magnetostrictive Actuator Considering Magnetic Flux Leakage

堆栈式超磁致伸缩制动器(SGMA)因其能量密度高、响应速度快且便于提供稳定的偏置磁场而得到广泛应用。由于永磁体和超磁致伸缩材料相对磁导率极低,磁路中存在明显的磁场空间分布不均匀的现象,磁-机耦合导致其动力学相较于传统结构的制动器更为复杂。为了准确地预测SGMA的输出特性,该文基于有限元仿真搭建了计及漏磁的等效磁路,并结合Jiles-Atherton模型、非线性本构模型及考虑分布特性的结构动力学模型,借助Pspice电路仿真软件建立了超磁致伸缩制动器多物理场耦合动态模型。相较于传统的制动器多场耦合模型,所提模型能够更精准地分析磁路中的漏磁行为,并反映由磁场不均匀引起的力学分布特性。最后搭建制动器输出位移测试平台以验证模型的准确性,模型计算结果与实验结果吻合度良好,证明了所建立模型能有效表征SGMA的输入-输出特性。

Stacked giant magnetostrictive actuators(SGMAs)have been widely used due to their high energy density,fast response speed,and convenience in providing a stable bias magnetic field.Due to the very low relative magnetic permeability of permanent magnets and giant magnetostrictive materials,there is obvious spatial distribution inhomogeneity in the magnetic circuit,and the magneto-mechanical coupling makes its dynamics more complicated than that of conventional actuators.Existing studies typically use magnetic flux leakage coefficient and traditional single-degree-of-freedom model to describe magnetic leakage behavior and dynamic output characteristics,which cannot accurately calculate the magnetic field intensities nor characterize the uneven mechanical distribution characteristics of the SGMA.To address these issues,this paper built a multi-physics model considering magnetic flux leakage to predict the output characteristics of SGMA accurately.Firstly,an equivalent magnetic circuit(MEC)model is built based on the results of finite element simulation.The distribution of magnetic field lines inside the actuator can be analyzed and the types of flux transistors can be divided through the finite element simulation results,combining with the SGMA internal structure and related dimensional parameters,the relevant magnetoresistance in the MEC can be calculated completely,which completes the coupling of the electro-magnetic domain and characterize the inhomogeneity of the magnetic field inside the actuator fully.Secondly,the magnetization process is completely modeled with the classical Jiles-Atherton model,and the coupling of the magneto-mechanical domain is completed by the nonlinear constitutive model.Thirdly,based on the traditional single-degree-of-freedom model,the structural dynamics model considering distribution effects is established by rederiving the equivalent mass with the help of the kinetic energy theorem,which reflects the force and strain distribution caused by magneto-mechanical coupling of different GMM rods.Finally,with the assistance of Pspice circuit simulation software,a multi-physics coupling dynamics model of SGMA is established and the actuator output displacement is solved.In addition,an SGMA prototype is fabricated and an experimental platform for displacement measurement of SGMA is constructed.Compared with the experimental data and this purposed model results of the input-output characteristics of the SGMA at different frequencies,the calculated results of the model were in good agreement with the experimental results,the maximum absolute error of the output displacement at the maximum excitation current is 0.54μm,and the relative error is about 9.3%,suggesting that the proposed multi-physics dynamic model can accurately predict the tracking behaviors of the SGMA prototype to the excitation signals and describe its dynamic output characteristics,and fully characterize the attenuation and hysteresis variation trend of actuator output displacement effectively.Through further discussion of this purposed model,the influence of magnetic flux leakage and strain distribution on the output displacement of the SGMA is analyzed,and the necessity and accuracy of the magnetic flux leakage modeling and the dynamic model considering the mechanical distribution characteristics in this paper are verified.The following conclusions can be drawn from the discussion above:compared with the traditional multi-physics coupling model of the actuators,the proposed model in this paper can more accurately analyze the magnetic flux leakage behavior in the magnetic circuit and reflect the mechanical distribution characteristics caused by the non-uniform magnetic field.