A thermally-responsive fiber engine in a linear temperature field

Abstract

Recently, many intriguing phenomena of the thermally responsive fiber-mass system in the inhomogeneous temperature field such as harvesting energy directly from the environment to maintain its self-oscillation have been observed, and have various potential applications. Challenges remain in the study of this complex thermodynamic coupled nonlinear dynamics problem. This paper abstractly presents a fiber engine module, establishes its constitutive model and asymptotic relationship, and demonstrates their conveniences in several cases of the fiber-mass systems. The asymptotic relationship is similar to the Kelvin-Voigt viscoelastic model consisting of a dashpot and a spring. Through several typical cases with different characteristic times of heat transfer, the fiber in a linear temperature field has three kinds of behaviors: damper, spring and engine. The fiber engine module can absorb energy from the environment and vibrate spontaneously, and even has the potential to drive a machine jumping on a hot surface. Furthermore, a stirrer driven by the fiber engine module is explored and the optimal characteristic time for maximum power density is found to be 0.5. The fiber engine module proposed can advance the understanding of the fiber-mass system and provide convenience for its applications in the fields of soft robotics, micro/nano devices, and biomedical instruments.