Equilibrium kink-like torsion deformation of a magnetoactive elastomer under a magnetic field

A novel effect involving the formation of a stable kink-like torsion deformation in a magnetoactive elastomer (MAE) beam subjected to a uniform magnetic field is theoretically predicted and experimentally confirmed. The phenomenon was demonstrated using an elastomer beam containing soft magnetic carbonyl iron microparticles within a silicone matrix. The torsion kink acts as a transition boundary between two undeformed homogeneous states of the beam. We show that the elastic moment is compensated by a magnetoelastic moment in the kink region, where the local magnetization of the beam is noncollinear to the applied magnetic field due to shape anisotropy. It is established that within the kink region, the MAE beam exists in a nonuniformly elastically deformed, low-symmetry magnetic state. Outside the kink, the beam's magnetization is collinear with the magnetic field, corresponding to an undeformed, high-symmetry homogeneous magnetic state.