Thermally driven self-oscillation of an elastomer fiber with a hanging weight

Self-excited motion has been recently extensively explored for various applications ranging from autonomous systems to energy harvesting devices. Our recent experiment has discovered that an ultrathin thermally responsive liquid crystal elastomer (LCE) fiber with a hanging weight can self-oscillate in a steady temperature field. Compared to many systems previously studied, which can generate self-excited motions when subjected to time-invariant stimuli such as light and humidity, the LCE fiber–mass system is simple and its heat-driven self-oscillation is very robust. During the self-oscillation, the LCE fiber continuously converts thermal energy to mechanical work, making it capable of harvesting low-grade waste heat. In this paper, we formulate a nonlinear dynamic theory for the system to understand its heat driven self-oscillation behavior. We have further obtained asymptotic solutions of the system with a few assumptions.