Pull-out resistance of shape memory alloy nickel-titanium ribbons embedded in silicone matrix for development of flexible composites

Active flexible composites can be developed through the coupling of silicone matrices and smart materials such as NiTi shape memory alloys (SMA). This work evaluates the mechanical behavior and adhesion of NiTi SMA ribbons embedded in a silicone matrix for the development of active flexible composites. Ribbons with cross-section of 0.15 × 0.8 mm ² were cold-rolled from superelastic NiTi wires with 0.4 mm in diameter. These ribbons were heat treated to either obtain characteristics of superelasticity (SE) or shape memory effect (SME) at room temperature. Silicone, NiTi wire, and ribbons were characterized by Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), and tensile tests. Adhesion between SMA ribbons and silicone matrix was evaluated with pull-out tests. The use of an adhesion promoter proved to be indispensable to ensure a good pull-out strength and shear stress at the NiTi ribbon and silicone interface. A silicone rubber cylinder with an embedded SME ribbon was built to evaluate the functionality of the NiTi ribbon in the development of flexible structures, which was demonstrated by the resistive heating and deformation of the SMA/silicone rubber composite.