Chaotic motion behaviors of liquid crystal elastomer pendulum under periodic illumination

The active material of liquid crystal elastomer (LCE) is capable of harvesting energy directly from the surroundings and sustaining continuous motion in the presence of light and heat. It is extensively employed in active machinery, soft robotics, biomedicine, and other fields. To date, there is barely any research on the sustained chaotic motion system of LCE pendulum. The main objective of this paper is to put forward a sustained motion system of a simple pendulum comprising photosensitive LCE. In accordance with the LCE dynamic model, a nonlinear dynamic model of the LCE simple pendulum is established, and its motion behavior characteristics under periodic illumination are examined. The numerical outcomes demonstrate that apart from the in-situ vibration mode, the LCE pendulum experiences two types of displacement motion modes as well, namely periodic oscillation mode and chaotic motion mode. The mechanism underlying the sustained periodic oscillation and chaotic motion is revealed by compensating for the damping dissipation with work done by the LCE contraction. Moreover, the discussion also covers how the system parameters affect the motion modes of the LCE simple pendulum. Through altering the parameters such as illumination period, contraction coefficient, light intensity, damping coefficient and gravitational acceleration, it is possible to realize the distinct motion modes of the LCE simple pendulum. This research may deepen the comprehension on the motion behavior of the simple pendulum, and provide scientific guidance for the design and exploration of chaotic systems based on active materials.