Model and experimental verification on actuator of magnetically controlled shape memory alloy

Magnetically controlled shape memory alloy (MSMA) is a new functional material which is found in recent years. The material can produce large induced strain by magnetic field, and has fast dynamic response, high efficiency of electromagnetic-mechanical conversion and excellent controllability. High strains of 10-15% for MSMA materials with different structure are achieved [1, 2]. The complete field-induced strain can be obtained in 250 μs [3]. Usual applications of the MSMA are actuators that produce linear motion [4-6]. Currently, MSMA has been successfully actuated at frequencies well above 1 kHz. To realize the applications of the magnetically controlled shape memory alloy needs to foresee the MSMA output in different external conditions. The physical modeling contributes to research magnetically controlled shape memory effects of the MSMA material. Although the research model obtained a better experimental verification at present, but these models only are established basing on the deformation mechanism of MSMA material itself, there isn’t the completely description of mathematical model for the external characteristic of MSMA actuators. In order to guide the design, control and application of the actuator, it is necessary to develop the research work of the actuator model. On the basis of thermodynamic models and the computational method of magnetic field-induced stress, considering the influence of the magnetic field, pre-pressure and temperature, the models of output strain and force are established for the MSMA actuator in this paper. The model provides theoretical foundation for the design and engineering application of the MSMA actuator.