1. Unimorph Shape Memory Polymer Actuators Incorporating Transverse Curvature in the Substrate

Shape memory polymers (SMP) utilized in reconfigurable structures have the potential to be used in a variety of settings. This paper is primarily concerned with the use of Veriflex-S shape memory polymer and bi-directional carbon fiber in a unimorph actuator configuration. One of the major deficiencies of SMP unimorphs is the permanent set (unrecovered shape) after a single or multiple temperature cycle(s). The novel concept of incorporating transverse curvature in the composite substrate, similar to that of an extendable tape measurer, was proposed to improve the shape recovery. A set of experiments was designed to investigate the influence of transverse curvature, the relative widths of SMP and composite substrates, and shape memory polymer thickness on actuator recoverability after multiple thermomechanical cycles. Flat carbon fiber and shape memory polymer unimorph actuators were evaluated for performance versus actuators of increasing transverse curvature. Digital image correlation was implemented to quantify the out-of-plane deflection of the unimorph composite actuators (UCAs) during the actuation cycle. Experimental results indicate that an actuator with transverse curvature significantly reduces the residual deformation while increasing the shape memory recoverability which could be further tailored to enhance the performance of shape memory polymers in reconfigurable arrangements.