Shape memory alloy wire reinforced composites for structural damage repairs

Shape memory alloys (SMA) have demonstrated their potential use in various smart structural applications. SMA undergo a reversible phase transformation from martensite to austenite as temperature increases. This transformation leads to shape recovery and to the associated recovery strains. SMA can also be used to enhance the capacity of a damaged structure, especially adhesively bonded joints. One approach is to use SMA-reinforced patches for enhancing adhesively bonded joints. To this end a design strategy, by which one can integrate the properties of SMA reinforcement to improve the interlaminar stresses of the bonded joint must be developed. Therefore, an analytical solution for evaluation of the stresses in a SMA wire reinforced composite patch used for repairing cracks in banded joints was created. The variables considered in the model are the fraction of SMA wires, the associated phase transformation strain, patch thickness, and adhesive layer's thickness and mechanical properties. A finite element analysis (FEA) was also conducted to verify the integrity of the results obtained through the proposed solution, and good agreement was obtained.