POLYACRYLAMIDE GELS FILLED WITH FERROMAGNETIC ANISOTROPIC POWDER - A MODEL OF A MAGNETOMECHANICAL DEVICE

The concept of a magnetomechanical system able to show permanent magne tization if compressed or to deform in a uniform magnetic field, is pr esented. The system design is based on polyacrylamide gel filled with demagnetized hard ferrite particles. The ferrite filled gel is deforme d by plane strain compression and magnetized while compressed. The ori entation of individual magnetized particles was randomized upon compre ssion release. Such samples exhibit no magnetic moment if decompressed and produce magnetic field intensity from 3 to 30 G if compressed. Th e samples exposed to external uniform magnetic field show macroscopic contraction or expansion of up to 40% of the initial dimensions. The m ost efficient ferrite was neodymium ferrite in the form of flakes. (C) 1995 John Wiley & Sons, Inc.