A structure includes a polymer structural member, which may include a shape memory polymer material, that can change its size and/or shape. An electromagnetic source is used to impose an electric field or a magnetic field on the polymer structural material, in order to control the shape of the material. The force may be used to change the shape of the material and/or to maintain the shape of the material while it is under load. The polymer material may be a solid material, may be a foam, and/or may include a gel. A shape memory polymer material may have mixed in it particles that are acted upon by the electromagnetic field. The structure may be used in any of a variety of devices where shape change (morphing), especially under loading, is desired.