Multifunctional Ferromagnetic Shape Memory Alloy Transducers with Novel Drive Mechanism

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Abstract 0409512Marcelo DapinoOhio State Univ.Due to the poor frequency bandwidth and low energy density of current nickel manganese gallium (Ni-Mn-Ga) devices, these materials have not made a successful transition from the laboratory to the commercial arena. These limitations are addressed in this proposal by means of a paradigm shift in material preparation and transducer design, which consists of driving the material with the stress and magnetic field aligned collinearly along the [100] direction, as opposed to the existing perpendicular configuration. The collinear configuration will enable a new class of broadband, multifunctional, compact and energy efficient Ni-Mn-Ga actuators and sensors. Applications will include vibration control, adaptive optics, health monitoring and underwater communications, among others. While the existence of magnetoelastic responses in this configuration is not supported by the existing theories for martensitic variant reorientation, recent measurements conducted by the PI demonstrate such responses and lay the groundwork for this research. The objectives of the research are to determine the exact origin of these unexpected measurements and to identify, quantify and develop design and material processing criteria to enable a new class of ferromagnetic shape memory actuators and sensors in which the magnetic field and stress are aligned collinearly. To that end, the research comprises three primary tasks: (1) to develop innovative material and device models for Ni-Mn-Ga driven with a collinear magnetic field and stress; (2) to conduct experimental tests at scales ranging from microscopic to macroscopic aimed at determining the microstructure and macroscopic behaviors of these alloys; and (3) to construct Ni-Mn-Ga actuators which can change their compliance while providing force and displacement control, and Ni-Mn-Ga multifunctional sensors.