Uniformity-based Magnetic Field and Improvement of Conversion Efficiency for Rotary Ultrasonic Machining Applications

A giant magnetostrictive transducer is a highly integrated device that facilitates the conversion of magnetic energy into mechanical energy, enabling the generation of motion or force during actuation. However, the energy efficiency of giant magnetostrictive materials (GMM) is hindered by several factors, resulting inless-than-optimal performance. To improve energy conversion efficiency, a magnetic circuit control strategy for optimizing the transducer is proposed, focusing on increasing magnetic flux density and enhancing magnetic field uniformity. Theoretical derivations demonstrate the positive correlation between magnetic circuit parameters, flux density, and uniformity. The impact of various magnetic circuit parameters on magnetic field strength is then analyzed using COMSOL software, which identifies optimal parameters for the stacked structure, resulting in a 9% improvement in magnetic field uniformity. Impedance analysis experimentally validates these results. The optimized stacked magnetic circuit for GMM shows a larger impedance circle diameter, an improved mechanical quality factor, and 95% magnetic field uniformity. By appropriately arranging the bias magnetic field and fine-tuning the magnetic circuit structure, magnetic flux density and uniformity along the GMM rod's central axis are enhanced,reluctance is reduced, and magnetic flux leakage is minimized in the closed magnetic circuit, which ensures high energy conversion efficiency in high-power ultrasonic vibration systems. The study provides essential guidance for optimizing system design and offers valuable insights to improve system efficiency and performance significantly.