Chaotic self-oscillation of liquid crystal elastomer double-line pendulum under a linear temperature field

Chaotic self-oscillation systems are prevalent in nature and hold promise for applications in soft robotics, energy harvesting and medical equipment. Nevertheless, current research on chaotic motion systems remains insufficient. This paper introduces an innovative chaotic self-oscillation system under a linear temperature field, comprising two liquid crystal elastomer (LCE) fibers and a mass ball. Unlike traditional single pendulum systems, the present double-line pendulum system not only realizes chaotic self-oscillation due to the non-synchronous characteristics of two LCE fibers contraction and expansion, but also provides a new theoretical framework and mechanism. To better understand the self-oscillation behavior of the system, the nonlinear dynamic model is established by combining the linear temperature field model and the dynamic principle. Numerical calculations indicate that the system exhibits two typical self-oscillation modes: periodic self-oscillation and chaotic self-oscillation. By analyzing the work done by various forces on the mass ball, the mechanisms underlying periodic self-oscillation and chaotic self-oscillation are elucidated. Furthermore, a detailed study is conducted on the effect of key system parameters on self-oscillation behavior. The conversion of self-oscillation mode can be realized by adjusting the system parameters. It is further proved by an experiment that the system can generate chaotic self-oscillation under the linear temperature field. The research results broaden the understanding of the motion properties of active materials and extend the scope of pendulum studies, thereby helping to advance technology in the fields of sensing and actuation, controllers, biomimetic mechanics and nonlinear oscillation.