Application of change in permeability of magnetic shape memory (MSM) alloys for optimization of magnetic circuit in actuators

Magnetic shape memory alloys, especially Ni-Mn-Ga alloys have been shown to have enormous potential to be used in electromagnetic (EM) actuators and sensors due to very long lifetime, fast response time, and large magnetic strain. They change their shape when subjected to external magnetic field. A number of physical phenomena accompanying the shape change also open up prospects for self-sensing or energy-harvesting applications. This paper concerns the use of changes in permeability of MSM alloys with strain to optimise actuator design. This is shown for a basic MSM actuator with very small air gap. Comparison of designs with and without “pre-strained” MSM element is presented based on field modelling results.