Simulation Of Advanced SMA Applications: Porous and Self-Healing Structures

The unique properties of shape memory alloys (SMAs) have enabled the material great potential applications in many fields including aerospace and biomedical engineering. Among these, the potential of porous and self-healing SMA structures are especially attractive. Porous SMAs are expected to be used as bone implants in biomedical field while self-healing SMAs, envisioned as reinforcements in composites, are promising in aeronautics engineering for the function of self-repair and damage mitigation. In this work, a series of finite element simulations of porous and self-healing SMA structures are performed to investigate the mechanical behaviors of these structures, so as to help expedite commercialization of these technologies.

It was found the architecture of pores plays a significant role in determining the characteristics of the architecture and optimizing the properties of porous SMAs. In this study, pore architectures with different numbers, sizes and location distributions are analyzed. Comparison of results of idealized arrays of holes with an actual porous microstructure is also studied. Key variables charactering the porous SMA behavior are discussed, and these can guide the optimization of pore architectures.

For self-healing SMAs, a SMA-reinforced notched composite is modeled to simulate fracture propagation and crack closure. In addition, studies are preformed on various SMA reinforcement interfacial conditions and architectures including multi-axial orientations, ply constructions, and reinforcement wire length. Results on geometric impact on fracture mechanics are presented as well as the effect of reduced stress concentrations and plastic deformation in the composite structures for ideal wire placement and interfacial conditions.