Characterization And Optimal Design Of Giant Magnetostrictive Actuators

Giant Magnetostrictive Material(GMM)is a new type of smart material,Because it has the advantages of large output force,fast response,high positioning accuracy,and large strain variation,Widely used in magnetic-mechanical actuators,magnetic-acoustic transducers,various new sensors,etc.Among them,Giant magnetostrictive actuator(GMA)with GMM as the core has become a hot research Giant topic at home and abroad.Foreign research technology on GMA design has been quite mature,however,its core technology is strictly confidential,and products and technologies are restricted from export to our country,China's research on the design and performance of GMA is still in its initial stage,in this context,the laboratory designed and processed finished GMA products for output performance analysis.In this paper,we build an experimental platform and analyze the output characteristics of the finished GMA products,the designed GMA was found to have problems such as severe heat and poor energy dissipation and large hysteresis.Optimize the design of GMA for the problems that arise,significantly improved GMA output performance after optimization over pre-optimization.The main work completed for the thesis is as follows:(1)Dynamic model of GMA axial direction transfer function using the first piezomagnetic equation and the law of conservation of energy,Analyze the effect of this structure on the dynamic performance of GMA in conjunction with the laboratory designed GMA structure.Numerical simulations show that: A single increase in GMM bar radius and a decrease in GMM bar length and load mass can effectively improve GMA dynamic performance.At the same time,the influence of the values of the structural parameters on the dynamic performance of GMA is taken into account,and the optimal parameters for the best magnetic-mechanical performance of GMA are optimized.(2)The experimental platform was built with the existing GMA,and the following experimental studies were conducted to collect and analyze the experimental data on the built platform:Analysis of bias on GMA output characteristics;the relationship between displacement and current with and without bias at low frequencies;Effect of current and frequency on GMA output displacement;analysis of hysteresis effect at low frequency.Experiments showed that: By applying an appropriately sized bias magnetic field to the GMA,the GMA is able to produce a larger output displacement and eliminate the frequency doubling phenomenon;The input current and output displacement have the characteristics of saturation and hysteresis;As the current increases,the GMA output displacement increases,as the frequency increases,the output displacement becomes smaller,becomes smaller very quickly,and there are problems such as serious heat generation and poor energy dissipation.(3)Analysis based on GMA experimental data and finite element modeling of its structure using Comsol.The relationship between the output displacement of GMA and time is studied by analyzing when the frequency and current parameters are changed.The results show that: Under the same parameters,the simulation results of the finite element model and the designed GMA experimental data can be in good agreement.Validate the correctness of the GMA model and analysis method established by Comsol,and provide reference for the comparison of the optimized GMA data,it also has some guidance for the optimization and design of GMA.(4)This paper firstly optimizes the design of GMA drive coil,bias magnetic field and pre-pressure design to solve the problems of GMA such as serious heat generation;Next,the parameters of the closed magnetic circuit were continuously changed and finite element simulation was performed using Ansoft Maxwell 18software;Determine an optimal structure size by analyzing the axial magnetic field strength and uniformity of GMM bars.Substitute the optimal structural dimensions into the finite element model created by Comsol software,Observe the relationship between GMA output displacement and output displacement rate of change at different currents and different frequencies before and after optimization,and compare and analyze.The results show that: Under the same experimental conditions,the optimized GMA output displacement and output displacement rate of change are substantially improved than before optimization,meet the design specifications.