In order to predict the performance of magnetostrictive smart material and pushits applications in engineering, it is necessary to build the constitutive relations for themagnetostrictive material Galfenol. For Galfen...In order to predict the performance of magnetostrictive smart material and pushits applications in engineering, it is necessary to build the constitutive relations for themagnetostrictive material Galfenol. For Galfenol rods under the action of the pre-stress andmagnetic field along the axial direction, the one-dimensional nonlinear magneto-mechanicalcoupling constitutive model is proposed based on the elastic Gibbs free energy, where theTaylor expansion of the elastic Gibbs free energy is made to obtain the polynomial forms. Andthen the constitutive relations are derived by replacing the polynomial forms with the propertranscendental functions based on the microscopic magneto-mechanical coupling mechanism.From the perspective of microscopic mechanism, the nonlinear strain related to magneticdomain rotation results in magnetostrictive strain changing with the pre-stress among theelastic strains induced by the pre-stress. By comparison, the predicted stress-strain,magnetostrictive strain, magnetic induction and magnetization curves agreed well withexperimental results under the different pre-stresses. The proposed model can describe notonly the influences of pre-stress on magnetostrictive strain and magnetization curves, butalso nonlinear magneto-mechanical coupling effect of magnetostrictive materialsystematically, such as the Young’s modulus varying with stress and magnetic field. In theproposed constitutive model, the key material constants are not chosen to obtain a good fitwith the experimental data, but aremeasured directly by experiments, such as the saturationmagnetization, saturation magnetostrictive coefficient, saturation Young’s modulus, linearmagnetic susceptibility and so on. In addition, the forms of the new constitutive relationsare simpler than the existing constitutive models. Therefore, this model could be appliedconveniently in the engineering applications.展开更多
Exchange coupling multilayer thin films, which combined giant magnetostriction and soft magnetic properties, were of growing interest for applications. The TbFe/FeAl multilayer thin films were prepared by dc magnetron...Exchange coupling multilayer thin films, which combined giant magnetostriction and soft magnetic properties, were of growing interest for applications. The TbFe/FeAl multilayer thin films were prepared by dc magnetron sputtering onto glass substrates. The microstructure, magnetic, and magnetostrictive properties of TbFe/FeAl multilayer thin film was investigated at different annealing temperatures. The results indicated that the soft magnetic and magnetostrictive properties for TbFe/FeAlmultilayer thin film compared with TbFe single layer film were obviously improved./n comparison with the intrinsic coercivity JHo of 59.2 kA/m for TbFe single layer film, the intrinsic coercivity jHc for TbFe/FeAl multilayer thin films rapidly dropped to 29.6 kA/m. After optimal annealing （350 ℃×60 min）, magnetic properties of Hs=96 kA/m and jHc=16 kA/m were obtained, and magnetostrictive coefficient could reach to 574×10^-6 under an external magnetic field of 400 kA·m^-1 for the TbFe/FeA1 multilayer thin film.展开更多
This paper presents a fully coupled model to account for the flux pinning induced giant magnetostriction in type-Ⅱ superconductors under alternating magnetic field The superconductor E-J constitutive law is character...This paper presents a fully coupled model to account for the flux pinning induced giant magnetostriction in type-Ⅱ superconductors under alternating magnetic field The superconductor E-J constitutive law is characterized by power law where the critical current density is assumed to depend exponentially on the flux density. The governing equations of the two-field problem （i.e., the interactions of elastic and magnetic effects） are formulated in a two-dimensional model. The magnetostriction curves and magnetization loops are calculated over a wide range of parameters. The effects of applied magnetic field frequency f and amplitude B0 and critical current density on magnetostriction and magnetization are discussed. Results show that the critical current density of high temperature superconductor （HTS） YBCO has a significant effect on the magnetization and magnetostriction. The pinning-induced magnetostriction which has been observed in experiment can be qualitatively simulated by this model.展开更多
为进一步研究超磁致伸缩材料磁能损耗特性,将棒状Terfenol-D材料沿着不同磁化方向进行切片,制成多个方形环状薄片样品,对比分析了材料磁化方向以及样品尺寸对磁能损耗的影响。在不同驱动磁场频率和磁密幅值下,对磁能损耗进行测试,分析...为进一步研究超磁致伸缩材料磁能损耗特性,将棒状Terfenol-D材料沿着不同磁化方向进行切片,制成多个方形环状薄片样品,对比分析了材料磁化方向以及样品尺寸对磁能损耗的影响。在不同驱动磁场频率和磁密幅值下,对磁能损耗进行测试,分析损耗实测数值变化趋势。基于损耗分离法,结合实测数据,考虑了材料内部涡流集肤效应及动态磁滞特性等影响,对高频磁能损耗进行了数值模拟,研究各项损耗系数变化规律。结果表明,Terfenol-D材料高频磁能损耗随着频率及磁密幅值增加,整体呈数值增大、增速加快趋势。在高频下,损耗系数为随着频率和磁密幅值变化的变量。当频率大于5 k Hz、磁密幅值大于0. 05 T时,数值模拟方法所得计算值与实测值的平均误差为3%。展开更多
基金supported by a grant of the Fund of the NationalNatural Science Foundation of China (No. 11472259)the Natural Science Foundation of Zhejiang Province (No. LR13A020002)。
文摘In order to predict the performance of magnetostrictive smart material and pushits applications in engineering, it is necessary to build the constitutive relations for themagnetostrictive material Galfenol. For Galfenol rods under the action of the pre-stress andmagnetic field along the axial direction, the one-dimensional nonlinear magneto-mechanicalcoupling constitutive model is proposed based on the elastic Gibbs free energy, where theTaylor expansion of the elastic Gibbs free energy is made to obtain the polynomial forms. Andthen the constitutive relations are derived by replacing the polynomial forms with the propertranscendental functions based on the microscopic magneto-mechanical coupling mechanism.From the perspective of microscopic mechanism, the nonlinear strain related to magneticdomain rotation results in magnetostrictive strain changing with the pre-stress among theelastic strains induced by the pre-stress. By comparison, the predicted stress-strain,magnetostrictive strain, magnetic induction and magnetization curves agreed well withexperimental results under the different pre-stresses. The proposed model can describe notonly the influences of pre-stress on magnetostrictive strain and magnetization curves, butalso nonlinear magneto-mechanical coupling effect of magnetostrictive materialsystematically, such as the Young’s modulus varying with stress and magnetic field. In theproposed constitutive model, the key material constants are not chosen to obtain a good fitwith the experimental data, but aremeasured directly by experiments, such as the saturationmagnetization, saturation magnetostrictive coefficient, saturation Young’s modulus, linearmagnetic susceptibility and so on. In addition, the forms of the new constitutive relationsare simpler than the existing constitutive models. Therefore, this model could be appliedconveniently in the engineering applications.
基金the Shanghai Municipal Nature Science Foundation (05NZ03)the Leading Academic Discipline Project of the Shang-hai Education Commission, China (XK0706)
文摘Exchange coupling multilayer thin films, which combined giant magnetostriction and soft magnetic properties, were of growing interest for applications. The TbFe/FeAl multilayer thin films were prepared by dc magnetron sputtering onto glass substrates. The microstructure, magnetic, and magnetostrictive properties of TbFe/FeAl multilayer thin film was investigated at different annealing temperatures. The results indicated that the soft magnetic and magnetostrictive properties for TbFe/FeAlmultilayer thin film compared with TbFe single layer film were obviously improved./n comparison with the intrinsic coercivity JHo of 59.2 kA/m for TbFe single layer film, the intrinsic coercivity jHc for TbFe/FeAl multilayer thin films rapidly dropped to 29.6 kA/m. After optimal annealing （350 ℃×60 min）, magnetic properties of Hs=96 kA/m and jHc=16 kA/m were obtained, and magnetostrictive coefficient could reach to 574×10^-6 under an external magnetic field of 400 kA·m^-1 for the TbFe/FeA1 multilayer thin film.
基金supported by the National Natural Science Foundation of China(Nos.11272140,10902046,11032006 and11121202)the Fundamental Research Funds for the Central Universities(lzujbky-2015-176)National Key Project of Magneto-Constrained Fusion Energy Development Program(2013GB110002)
文摘This paper presents a fully coupled model to account for the flux pinning induced giant magnetostriction in type-Ⅱ superconductors under alternating magnetic field The superconductor E-J constitutive law is characterized by power law where the critical current density is assumed to depend exponentially on the flux density. The governing equations of the two-field problem （i.e., the interactions of elastic and magnetic effects） are formulated in a two-dimensional model. The magnetostriction curves and magnetization loops are calculated over a wide range of parameters. The effects of applied magnetic field frequency f and amplitude B0 and critical current density on magnetostriction and magnetization are discussed. Results show that the critical current density of high temperature superconductor （HTS） YBCO has a significant effect on the magnetization and magnetostriction. The pinning-induced magnetostriction which has been observed in experiment can be qualitatively simulated by this model.
文摘为进一步研究超磁致伸缩材料磁能损耗特性,将棒状Terfenol-D材料沿着不同磁化方向进行切片,制成多个方形环状薄片样品,对比分析了材料磁化方向以及样品尺寸对磁能损耗的影响。在不同驱动磁场频率和磁密幅值下,对磁能损耗进行测试,分析损耗实测数值变化趋势。基于损耗分离法,结合实测数据,考虑了材料内部涡流集肤效应及动态磁滞特性等影响,对高频磁能损耗进行了数值模拟,研究各项损耗系数变化规律。结果表明,Terfenol-D材料高频磁能损耗随着频率及磁密幅值增加,整体呈数值增大、增速加快趋势。在高频下,损耗系数为随着频率和磁密幅值变化的变量。当频率大于5 k Hz、磁密幅值大于0. 05 T时,数值模拟方法所得计算值与实测值的平均误差为3%。
