Design and characterization of magnetostrictive composites

2014 by Taylor & Francis Group, LLC. The term magnetoelasticity refers to the interaction of the elastic material and its magnetic state. Magnetoelasticity allows the analysis of magnetostriction or magnetic field-induced deformations. There are several magneto elastic effects; these are volume magnetostriction, Joule magnetostriction, dipolar magnetostriction, direct Wiedemann effect, and changes in the elastic properties due to magnetoelastic contributions (Lacheisserie 1993). The most commonly used magnetostriction effect was observed by the renowned physicist James Joule by documenting changes in length in ferromagnetic materials in the presence of a magnetic field. Joule magnetostriction refers to a deformation that transforms a spherical sample into an ellipsoid whose symmetry axis lies along the magnetization direction. The strain in the material can also result from orientation changes in small magnetic domains within the material. The magnetostriction response is observed in most ferromagnetic materials and can range from zero to nearly 1% in rare-earth-based intermetallic compounds. Values ranging from 1000 to 2000 microstrain are observed in fields ranging from 50 to 200 kA/m (Verhoeven et al. 1989). These strains are amplified if the sensor is operated in the dynamic range under the correct conditions. Certain magnetostrictive underwater transducers can outperform lead zirconate titanate transducers in the low-frequency domain (Hartmut 2007).

Design and characterization of magnetostrictive composites Chapter