Transformation of Embedded Shape Memory Alloy Ribbons

Shape memory alloy (SMA) wires can be embedded in a host material to alter the stiffness or modal response and provide vibration control. The interaction between the embedded SMA and the host material is critical to applications requiring transfer of loads or strain from the wire to the host. Although there has been a significant amount of research dedicated to characterizing and modeling the response of SMA alone, little research has focused on the transformation behavior of embedded SMAs. Photoelastic experiments with SMA wires in polymer matrices had previously provided a qualitative understanding of stress transfer in SMA composites. In the current work, 2D photoelasticity is utilized to quantify the internal stresses induced by the actuation of a thin SMA ribbon in a pure polymer matrix. Through the use of a CCD camera and a frame grabber, photoelastic images are digitally recorded at discrete time increments. Shear stresses induced during the actuation are calculated as a function of time. Computational predictions of shear stress are made using finite element analysis and compared with experimental observations.