Mechanics-based model for the cooking-induced deformation of spaghetti.

In this article, we propose a minimal model for the cooking-induced deformation of spaghetti and related food products. Our approach has parallels to the use of rod theories for the mechanics of slender bodies undergoing growth and is inspired by a wealth of experimental data from the food science literature. We use our model to investigate the cooking of a single strand of spaghetti confined to a pot and reproduce a curious three-stage deformation sequence that arises in the cooking process.

On Planar Discrete Elastic Rod Models for the Locomotion of Soft Robots.

Modeling soft robots that move on surfaces is challenging from a variety of perspectives. A recent formulation by Bergou et al. of a rod theory that exploits new developments in discrete differential geometry offers an attractive, numerically efficient avenue to help overcome some of these challenges. Their formulation is an example of a discrete elastic rod theory. In this article, we consider a planar version of Bergou et al.'s theory and, with the help of recent works on Lagrange's equations of motion for constrained systems of particles, show how it can be used to model soft robots that are composed of segments of soft material folded and bonded together. We then use our formulation to examine the dynamics of a caterpillar-inspired soft robot that is actuated using shape memory alloys and exploits stick-slip friction to achieve locomotion. After developing and implementing procedures to prescribe the parameters for components of the soft robot, we compare our calibrated model to the experimental behavior of the caterpillar-inspired soft robot.

Translucent soft robots driven by frameless fluid electrode dielectric elastomer actuators.

Dielectric elastomer actuators (DEAs) are a promising enabling technology for a wide range of emerging applications, including robotics, artificial muscles, and microfluidics. This is due to their large actuation strains, rapid response rate, low cost and low noise, high energy density, and high efficiency when compared with alternative actuators. These properties make DEAs ideal for the actuation of soft submersible devices, although their use has been limited because of three main challenges: (i) developing suitable, compliant electrode materials; (ii) the need to effectively insulate the actuator electrodes from the surrounding fluid; and (iii) the rigid frames typically required to prestrain the dielectric layers. We explored the use of a frameless, submersible DEA design that uses an internal chamber filled with liquid as one of the electrodes and the surrounding environmental liquid as the second electrode, thus simplifying the implementation of soft, actuated submersible devices. We demonstrated the feasibility of this approach with a prototype swimming robot composed of transparent bimorph actuator segments and inspired by transparent eel larvae, leptocephali. This design achieved undulatory swimming with a maximum forward swimming speed of 1.9 millimeters per second and a Froude efficiency of 52%. We also demonstrated the capability for camouflage and display through the body of the robot, which has an average transmittance of 94% across the visible spectrum, similar to a leptocephalus. These results suggest a potential for DEAs with fluid electrodes to serve as artificial muscles for quiet, translucent, swimming soft robots for applications including surveillance and the unobtrusive study of marine life.