Experimental Investigations Of Magneto-Mechanical Coupled Characteristics In Giant Magnetostrictive Materials

As a new type of functional material, giant magnetostrictive materials TbDyFe alloys have been applied commonly in many applications for the modern high and new technologies, due to their fast response, excellent magnetostrictive properties, high energy density, and relatively low magnetocrystalline. Whereas, the magnetoelastic properties of the TbDyFe alloys are nonlinear, which are affected by compressive stress, magnetic field and the magnetomechanical coupled loading of the magnetic field and compressive stress. These properties limit their extensive engineering applications and effect the accuracy and reliability of intelligential system. In this dissertation, the experimental studies of magnetomechanical coupled properties in TbDyFe alloys and dynamics properties with giant magnetostrictive actuator have been carried out.Firstly, the purpose is the revelation of the magnetoelastic properties for<110> oriented TbDyFe polycrystalline alloys with the high Tb/Dy composition ratio under the magnetomechanical coupled loading. The TbDyFe alloys are Tbo.27Dyo.73Fe1.95, Tbo.3Dyo.7Fe1.95and Tbo.45Dy0.55Fe1.95alloy. The measurements are reported on the magnetic, magnetostriction and mechanical properties for<110> oriented TbDyFe polycrystalline alloys under different both applied magnetic field and compressive stress along the rod axis. The results presented here are interpreted qualitatively by the magnetic domain rotation mechanism.Secondly, the investigation of the magnetostrictive material dynamic behavior is required, we fabricate experimental equipment and establish the relevant measurement and control software. The dynamic experiments of the magnetomechanical coupling characteristics for magnetostrictive material have been achieved. Measurement and Control Systems have been designed for automatic drive and data acquisition, which can measure the mechanics and physics parameters of dynamic constitutive model. Meanwhile, the properties are simultaneously measured and displayed of magnetoelastic response under the multi-field coupling loads. Furthermore, compare with commercial equipment and software, the ones fabricated can be enlarged function for oneself requirement, which are also convenient for application of anther dynamics research with measure and control.Employing dynamic experiments apparatus, the dynamic experiments have been carried out to inverstigate the dynamic properties of the TbDyFe polycrystalline alloys under varied operating conditions of applied the magnetomechanical coupled loading, such as the varied frequency and amplitude of magnetic field, compressive stress and bias magntic field. The results exhibit several dynamic behaviors of the TbDyFe alloys under different magnetomechanical coupled loading. It can be found that the frequency of the applied magnetic field influences strongly the dynamic properties of the TbDyFe alloys.Finally, the non-linear dynamics properties of the giant magnetostrictive actuator have been proposed. The output properties of giant magnetostrictive actuator are depended on the dynamic behavior of TbDyFe alloys and actuator device system structure. On the basis of the giant magnetostrictive actuator and the variational loading conditions for actuator device, the resonance frequencies are obtained by swept method. The output properties of giant magnetostrictive actuator are made by changing the exciting frequency and amplitude of magnetic field. The waveforms, phase portraits and amplitude spectrums are obtained to show and analyse complicated nonlinear dynamic properties of giant magnetostrictive actuator under the magnetomechanical coupled loading.Sumary, an experimental investigations of Magneto-Mechanical coupled properties in the giant magnetostrictive materials is developed, and the further study on theoretical modeling and the design and application of the corresponding intelligential devices problems can be carried out based on the work.