Deformation of ferrogels induced by nonuniform magnetic fields

Materials producing strain in magnetic fields are known as magnetoelastic or magnetostrictive materials. A new type has been developed and the elongation of magnetic field sensitive polymer gels, called ferrogels, has been studied. The driving force of the deformation is the magnetic field gradient which was produced by an electromagnet. Unidirectional deformation measurements have been performed and the dependence of elongation on the current intensity has been reported. An equation for the uniaxial magnetoelastic properties has been derived and it was proven that at small strains the elongation is proportional to the square of steady current intensity. The elastic modulus of ferrogels was found not to be influenced by the magnetic field. (C) 1996 American Institute of Physics.