Magnetic Shape Memory Alloy and Application in Structural Vibration Control

Abstract

Magnetic Shape Memory Alloys (MSMA) are attractive active materials because they have large strain (about 10%) as the classical shape memory alloys (SMA), but can provide a 100 times shorter time response, so, MSAM will be the ideal material of structural engineering vibration control. The main disadvantages of MSMA based actuators are the brittleness of the single-crystal material, the difficulty to apply the strong magnetic field required to obtain sufficient strain and the nonlinear behaviors. In this paper a novel MSMA based actuator changing the disadvantage of the hysteretic behaviors into an advantage. This device includes two pieces of MSMA material act in an opposite way. The hysteretic behavior of the material permits to keep a stable position when no current is applied. The use of current pulses permits also a reduction of the coil heating (Joule effect losses) and a reduction of the magnetic circuit size. The performances and characteristics of MSMA are between these of classical SMA and these of piezo-electric materials. A thermo-magneto-mechanical model of the actuator is currently in development in order to design an efficient control law well adapted to the specific MSMA properties.