Self-tapping of a liquid crystal elastomer thin beam above a hot plate

Thermally-driven self-oscillating systems are able to absorb heat from the environment to maintain their own motion, and therefore have a wide range of applications in the fields of signal processing, robotics and energy harvester. Existing thermally-driven self-oscillating systems are always in contact with a hot surface or in a temperature field with a non-contacting heat source, which makes it difficult to dissipate heat quickly and limits the generation of high-frequency oscillations. By introducing intermittent contact with a hot plate, a self-tapping liquid crystal elastomer (LCE) thin beam is experimentally designed in this paper. Based on the existing mature dynamic LCE model, the theoretical model of the thermally-driven self-tapping LCE beam is established, and the mechanism of self-tapping is elucidated. Numerical calculations show that the system exists in two modes of motion: static mode and self-tapping mode, which is consistent with the experimental results. The LCE beam maintains its self-tapping by absorbing the thermal energy from the hot plate to compensate for the damping dissipation during its motion. In addition, the effects of several key parameters on the amplitude and frequency of self-tapping are investigated in detail. Specially, the frequency of self-tapping exceeds 7 Hz, originating from the rapid heat absorption when contacting the hot plate and the rapid heat dissipation in air. This self-tapping system has the advantages of high oscillation frequency, simple structure, flexible regulation, and stability, and has potential applications in practical application scenarios such as thermal sensors, energy capture and micro-robotics.