Electrically controlled extension effects in soft solids

Some recent work has involved the incorporation of solids into soft matrices in order to acquire an improvement in their mechanical and damping performances [R. S. Lakes et al, Nature, Vol. 410, 565-567]. Other more general analytical works have dealt with the application of electrical and magnetic fields to susceptible materials, usually involving a relatively hard fluid filled sandwich. In the present note the effect of soaking soft porous solids in magneto or electro-rheological fluids (MRF or ERF respectively) on their stiffness is announced. In this case the pores or cells of the carrier soft solid hold polarisable solids. When the resulting composites are excited by a magnetic (MRF) or electric field (ERF) the stiffness of the sections thus produced are increased (in a passive sense) under loading. Unique results are obtained when auxetic MR soft soaked foams are excited - significant magnetostrictive effects are measured..