Modeling of Hybrid Shape Memory Alloy (SMA)- Ceramic Composites

A numerical model of a hybrid Shape Memory Alloy (SMA) – MAX phase ceramic composite is developed. To account for the different inelastic mechanisms found in the system, a recent 3D constitutive model for the SMA behavior and an elastic-plastic approximation of the MAX phase behavior are introduced. To study the effects of the microstructure on the system, a finite element mesh is generated from x-ray tomography results. By subjecting the composite to an isobaric actuation loading path, it is demonstrated that the effective composite response exhibits decreased transformation strains versus dense SMAs and that the associated transformation temperatures are shifted. Interestingly, through an actuation cycle, irrecoverable strains are generated in the MAX phase leading to a residual stress state in the composite. Such a stress state serves as a biasing load to take advantage of the ceramics superior mechanical response under compression.