SGER: A Finite Element Model for Thin Film Ferromagnetic Shape Memory Actuators

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ABSTRACTThe long-term vision of the proposed research project is the development of a novel type of actuation and sensing devices based on ferromagnetic shape memory alloy (FSMA) thin films. The project is part of an international collaboration between North Carolina State University (NCSU) and partners from the Institute for Micro-Systems Technology (IMT) at the University of Karlsruhe, Germany. It combines the capabilities at both institutes (IMT-micro-technologies, device characterization, and coupled finite element simulation, NCSU - materials testing, modeling and coupled finite element simulation) into a unique interdisciplinary research activity, which will promote a promising new generation of devices with great relevance to nano- and micro-engineering. The current phase of the research as proposed in this Small Grant Exploratory Research project addresses two important contributions to the overall goal.1. Development of a first version of a new thermo-magneto-mechanical model forFSMA. Based on previous work by the PI, his model for conventional SMA will beextended to account for temperature-dependent magnetic effects by means of aneffective magnetic force model. The model will be validated against experimentaldata provided by the German partner. 2. Based on this model, a novel multi-field finite element formulation for FSMAactuators will subsequently be developed and implemented into the IMT in-housecode. This will be done in close collaboration with the IMT group and requiremutual visits to guarantee successful completion. The finite element module willthen enable IMT to continue with its own part of the program and will be used fordesign and optimization of the thin-film devices on the basis of verified simulationsrather than trial-and-error methods.TECHNICAL MERIT: Recently, the German partner in this proposal has introduced anaward-winning novel actuation mechanism based on NiMnGa thin films, which makes use of a unique combination of ferromagnetism and conventional shape memory effects. This combination will enable the fabrication of micro- or nano-devices with integrated sensing and actuation capabilities featuring a considerable performance increase over comparable mechanisms. However, the successful device design depends strongly on the availability of realistic simulation tools, and for this purpose, the project will develop the first model for thermo-magneto-mechanical behavior of FSMA material in Task I.In Task II of the project, the material model will be implemented into a finite elementformulation to simulate the dynamic performance of the actuator system.BROADER IMPACT: This research will be possible through the close collaborationbetween IMT and NCSU, and it will help to establish a strong and long-lasting international partnership in an exciting and growing area of science.In addition, the results of the project will be integrated into the class MAE589D "Adaptive structures I - Active materials sensors and actuators", which has been developed by the NCSU PI. It will blend seamlessly into the class's integrated approach, featuring combined experimental and theoretical projects, and it is certain to spark the students' interest in the material.