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

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