Multiple Degree of Freedom Model of Giant Magnetostrictive Actuator

A specific giant magnetostrictive actuator (GMA) is developed for injectors in high-pressure-common-rail system. The magnetic strength, with its axial distribution unevenness considered, is determined by the driving current and axial dimension. Multiple degrees of freedom model of the specific GMA is established based on Jiles-Atherton (J-A) model and vibration theory. The number of degrees of freedom is optimized, and step response is calculated and its state-space model is provided and computed using MATLAB. Steady-state response and frequency response in moderate driving level is achieved and verified by the test results, and load contributed by fluid is regarded as elastic-damping load and the specific response of GMA in this case could be forecast. From the measured result, the proposed multiple degrees of freedom model are amenable to describe the stable response of the specific GMA under low frequency harmonic driving.