SMA active fiber pumps inspired by the squid mantle.

Squid possess a mantle that is able to quickly compress an internal fluid, thus providing a jetting locomotion that enables them to be the fastest aquatic invertebrates. The mantle possesses a complex collagen fiber and muscular system, and the primary propulsion is accomplished through circumferential muscles (90°) contracting around the mantel. In addition, jetting is enhanced through elastic energy stored in the helically-wound IM-1 collagen fibers. The angles of these fibers have been measured between 28° and 32° in different species of squid. Inspired by the muscular fiber configuration found in the mantle of squid, novel pumps that use shape memory alloy (SMA) active fibers oriented at precise angles around a cylindrical shell are investigated through experiments and analytical studies. A thermomechanical model of an SMA fiber is presented and the parameters are identified through experiments. Using the thermomechanical model of the SMA fiber, an analytical model of the SMA active fiber pump is presented and is validated through experiments. Results show that maximum pumping power and efficiency is achieved for pumps when the matrix modulus is less than the fiber modulus and the optimal fiber wind angle is ±55°. When the matrix modulus is similar to the fiber modulus, maximum pumping performance is achieved with a wind angle of ±90°, similar to the angle of the circumferential muscles in the squid mantel.