Biomimetic avian muscle work loop emulation via shape memory alloys

An aircraft wing is a multifarious system composed of numerous specialized subsystems (e.g., ribs, spars, and flaps). An avian musculoskeletal system is similarly multi-utility, performing the tasks of an actuator, a brake, and a spring with variable compliance. Biomimicking these natural systems could yield effective solutions for complex engineering problems. This work proposes the use of shape memory alloy wires subject to electro-thermomechanical stimuli to reproduce the work-loops performed by a humerotriceps of a pigeon. The biomimicked actuation cycles are achieved for temperature-driven (temperature regulated via a thermal chamber) or voltage-driven (Joule heating and natural convection cooling) experiments, leading to responses that are compatible with a range of brake and actuator applications. Consequently, net positive volume-specific work-loops utilizing SMA wire components are demonstrated for the first time using this approach. Furthermore, a numerical model accurately representing the experiment is calibrated and used for further exploring the design domain enabled by the thermomechanically stimulated smart actuators.