Internal Liquid Metal Channels to Enable High Power Additively Manufactured SMA Actuators

Shape memory alloys are capable of producing some of the highest actuation stresses (~300 MPa) of any active material. However, large monolithic SMA actuators, which can induce the tremendous forces required in some applications, are currently limited to low cyclic actuation frequencies due to their associated high thermal masses coupled with innate low thermal diffusivities of the material. An increase in the effective thermal diffusivity of an SMA actuator system will result in an increase in actuation frequency; accordingly, this would lead to the ability to perform more cycles over a given time interval and subsequently yield an overall higher actuator power density (energy density with time). This current work presents ongoing research in the design, manufacturing, enabling surface engineering (such as chemical etching and anodization), and testing of internal channel additively manufactured SMA actuator designs, including a tensile bar variation and planned testing of an optimized cantilever beam.