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Background Information. Magnetostriction first observed in iron by James Joule in 1842. Magnetostrictive material experiences strain and deformation in direction of applied magnetic field. Strain response changes when external stress is applied.
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Background Information • Magnetostriction first observed in iron by James Joule in 1842. • Magnetostrictive material experiences strain and deformation in direction of applied magnetic field. • Strain response changes when external stress is applied. • Terfenol-D, developed in the 1970s by the Naval Ordinance Laboratory, exhibits the largest known magnetostrictive response at room temperature.
Device and Experiment • Device built around adjustable air gap electromagnet capable of 3000 Gauss with 2 inch gap. • Accommodates data acquisition via optical microscopy or digital image correlation. • Can apply 30 MPa stress to sample. • Testing unimorphTerfenol-D based composite with naturally sourced matrix. • Objectives were to confirm magnetostriction as primary cause of deflection, and characterize sample response. • Classifying criterion established as seen in figure.
Results • Device capable of characterizing magnetostrictive response. • Confirmed magnetostriction as primary source of bending in all unimorph samples. • Can now proceed with assisting sample manufacturer with optimizing composite and testing future iterations.