Dynamic Experiments of Strain and Magnetic Field for Galfenol Rod and Its Modeling

Dynamic actuation experiments of an Fe83Ga17 (Galfenol) rod sample were conducted by the authors. A permanent magnet was used to apply a 2.25-kA/m bias field. Dynamic current through the excitation coils was applied to obtain a dynamic magnetic field. The frequencies of the dynamic field are 1, 10, 20, 40, 60, 100, 200, and 300 Hz. Hysteresis between the strain and dynamic magnetic field increases with increasing frequency. The power losses consist of hysteresis loss, classical eddy current loss, and anomalous (or excess) loss when Galfenol is excited by a dynamic field. To describe the hysteresis, a dynamic hysteresis model of Galfenol based on the energy-weighted average hysteresis equation, eddy current loss, and anomalous loss was used. The hysteresis loss was calculated using incremental volume fractions, which was evaluated using the energy-weighted average formula. The experimental results and model calculations agree well for frequencies below 200 Hz. The model can be used to guide the design of Galfenol dynamic applications in low frequency such as actuators and vibrators.