In this work, the magnetization response of FeMnAlNi superelastic shape memory alloys (SMAs) is investigated under stress. Wires with a diameter of 0.5 mm were subjected to repeated abnormal grain growth heat treatments in order to obtain bamboo structured oligocrystalline grains that are necessary for superelasticity. Solution heat treated wires were aged at 200ºC for 3 h to strengthen the austenite matrix. Tensile cyclic tests were performed at room temperature until failure, while the magnetization response of the wires was monitored using a hall sensor during loading and unloading in each cycle. It is observed that after each cycle, overall magnetization of the alloy decreases once the irrecoverable strain is introduced after large deformations and magnetization of the sample is inversely correlated with the irrecoverable strain. The findings of this work show that the magnetic shift in Fe-SMAs under deformation can be used a health monitoring tool in next generation structures to detect large deformations and cracks.
This study investigates a novel hybrid cooling method for more weight efficient thermal management of aerospace electric propulsion motors using thermal energy storage (TES) elements. The proposed system utilizes the latent heating of TES in the form of SAPO-34 zeolite slabs hydrated with water to maintain stable operating temperatures during takeoff. The TES operates in parallel with a fluid cooling system comprised of minichannel heatsinks attached to the stator windings and exterior air heat exchanger. Thermoelectric performance benefits of TES inclusion are evaluated using network analysis under assumed flight path load. Complex non-linear thermofluid and electromagnetic behaviors in the network are replaced with lookup table interpolants generated using results of numerical simulations swept across a series of input parameters. Subsequent solution of two-hundred systems with varying TES volume indicated a maximum TMS mass savings of 14.8% compared to the lightest thermal management system without TES inclusion.
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