Extraction Of Characteristic Parameters Of Giant Magneto Strictive Materials And Research On Transducer

The ocean plays a vital role in safeguarding national sovereignty and security.As the main carrier of ocean long-distance transmission of information,high-power lowfrequency electroacoustic transducer technology is of great significance for national economic development and marine national defense security.Giant Magnetostrictive Material(GMM),as a strategic new functional material,has excellent properties such as large magnetostrictive coefficient,high energy density and fast response speed.Therefore,GMM is an ideal material for manufacturing low-frequency high-power electro-acoustic transducer.Accurate and reliable GMM characteristic parameter extraction and loss prediction research are important foundations for the design of GMM transducers.However,the existing research on extraction of GMM characteristic parameters and losses is far from perfect.Therefore,in this paper,an impedance model is established to extract characteristic parameters of GMM considering losses.To verify the accuracy of parameter extraction and the accuracy of the built model,the longitudinal vibration GMM transducer is designed and manufactured as the experimental platform.Results show that works in this paper has provided an accurate and reliable method for the design of GMM transducer.Additionally,the hysteresis model is studied in this paper and the calculation and prediction of magnetic loss of GMM is realized.The main work and innovations of this thesis are as follows:(1)Aiming at a series of problems including unknown characteristic parameters of GMM under specific working conditions,high measurement cost of material characteristic parameters,difficulty to meet the measurement conditions,large measurement error,and complexity of finite element simulation for the loss calculation of GMM transducer under multi-field coupling,a GMM characteristic parameters testing platform and its plane wave model are built.Then a finite element simulation considering losses of the GMM transducer in the piezoelectric module is realized according to the piezomagnetic-piezoelectric analogy method.The comparability of GMM and piezoelectric materials in characterizing material loss and finite element governing equations are discussed in detail,and the feasibility of a simulation of GMM transducer considering losses in the piezoelectric module of COMSOL Multiphysics is analyzed.By using the material’s complex parameters to characterize the losses,a plane wave model with complex material coefficients is established on the GMM characteristic parameter test platform.The particle swarm optimization algorithm is used to extract the complex parameters of the material properties under different prestresses,and the extract parameters are substituted into COMSOL to carry out the harmonic analysis.Response analysis showe that the obtained results are in excellent agreement with the plane wave model results and the experimental impedance curve,which proved the feasibility and accuracy of the proposed material characteristic parameter extraction and finite element simulation method.(2)A longitudinal vibration GMM transducer is designed and manufactured,and it is used as an experimental platform to further verify the accuracy of the proposed method for extracting material characteristic parameters and the reliability of the established plane wave model.The plane wave model of the transducer is established by using the extracted complex parameters.The effect of eddy current varying with frequency is considered in the proposed model,and the structural dimensions of the transducer are optimized,including the front and rear mass blocks are determined.The magnetic circuit of the transducer is optimized,including eddy current suppression,coil heat dissipation and prestress design.Finally,according to the overall design structure of the transducer,an experimental prototype was made,and the performance of the transducer is tested.The results of the plane wave model with the finite element model are compared with the experimental results,Results show that the model outputs are in excellent agreement with the experiment results,which further verifies the accuracy and reliability of the established transducer model.(3)Since the performance of the GMM transducer is greatly affected by the magnetic loss of GMM,the prediction of the magnetic loss of GMM is an important prerequisite for the overall performance prediction of the transducer.Aiming at the problems that the magnetic loss of GMM is influenced by many factors and is difficult to be predicted,a Jiles-Atherton hysteresis model(JA model)that is widely applicable to different excitation amplitudes is established.A GMM hysteresis test platform is built to verify the applicability of the proposed model.In this paper,the magnetization mechanism of GMM and the characterization method of magnetic loss are expounded in detail,the influence of JA model parameters on the hysteresis loop is studied,and the correction coefficients are introduced to correct the parameters of the JA model,so that it can be applied to different excitation amplitudes.The JA dynamic model is established and the dynamic loss characteristic of the GMM is considered to expand the application range of JA model.The GMM hysteresis characteristic test platform is used to measure the B-H hysteresis loop of GMM under different excitations,and the JA model parameters are extracted by particle swarm optimization algorithm to simulate the hysteresis curves under different excitations.The shapes and size of the hysteresis loops are predicted,and the magnetic loss prediction of GMM was realized,which provided important data support for the reliable design of GMM transducers.