Design, Development and Characterisation of a Bundled SMA Actuator

Abstract

Due to small force developed by a single wire shape memory alloy (SMA) actuator, SMAs have found applications mostly in micro and miniature domains. However, to increase force output the bundles of SMA actuators are reported in literature. Existing bundle designs are merely parallel arrangement of individual wire actuators crimped at the ends using end plates. These designs are vulnerable to unequal strains and forces in the individual actuators. In this research, a novel bundle using a single 0.15 mm diameter wire actuator was designed and developed. The wire actuator was looped around Polytetrafluoroethylene (PTFE) coated pin supports to reduce frictional effects. The bundle was subjected to various actuation currents and corresponding strains were recorded. It was found that a 420 mA actuation current resulted in highest strain