Efficiency of finite element analyses of 55NiTi SMA actuators: Solid versus beam and shell modeling

A generalized solution scheme was utilized to specialize a recently-developed 3D multi-mechanism SMA model, thus making it suitable for the kinematical/statical constraints needed for modeling two-dimensional continua, shell analysis, as well as planar and spatial beam assemblages. The accuracy and computational efficiency of the scheme were assessed in the context of two specific geometries of 55NiTi SMA actuators; i.e., multi-coil helical spring and honeycomb panel, operating under one-way or two-way shape memory conditions. The emphasis is placed on the thermomechanical response of these SMA actuators, varying in geometrical complexity, under multiple thermal cycles. In all cases investigated, the beam modeling was found to be very efficient in comparison to the shell and 3D solid elements, and this was achieved without any loss of accuracy.