Finite element analysis of a 3D Fe-based SMA cellular beam with highly heterogeneous stress and strain distributions

Low-cost iron-based shape memory alloys (SMAs) have great potential for applications in large engineering parts. Their main drawback relates to their higher density compared to Nitinol and Cu-based SMAs, and can be compensated by using porous Fe-SMAs or by lightening the structures through the introduction of engineered cavities. In this manuscript, we simulate the thermomechanical response of a tapered Fe-Mn-Si beam with web openings using a 3D phenomenological model that was previously developed by the authors. The model is implemented in ABAQUS through a user defined material subroutine (UMAT). The results obtained by applying a pressure of 1 MPa and fixing both vertical ending faces show that, at room temperature, the smart beam can recover completely its initial shape. In contrast, a steel beam with the same geometry subjected to identical boundary conditions is found to fail at a much lower load. Even if the deformation of the SMA beam is dominated by plastic deformation as the loading temperature increases, its perfect shape memory effect at room temperature can be used to renovate architectural heritage or to design new smart structures.