Research on thermal actuation performance of twisted and coiled nylon artificial muscles based on yarn mechanics

Twisted and coiled artificial muscles (TCAMs) are recently introduced as novel structural actuators that offer outstanding performance. TCAMs consisting of nylon or other polymer fibers have the advantages of low cost, large stroke, and high power density, and can be used in the fields of robots and intelligent textiles. Manufacturing process and actuation conditions significantly affect the spiral structure of the fiber. Therefore, it is particularly important to conduct research on the manufacturing mechanics of TCAMs for their future development and applications. In this paper, a modeling based on yarn mechanics and the energy method is established for exploring the actuation performance of TCAMs. Firstly, we analyze the effects of the preparation and actuation conditions on the helical structure of TCAMs. The relationship between the spiral structure and the fiber tension is obtained. Then, we investigated the effects of preparation conditions, actuation load, and operating temperature on the tensile stroke of TCAMs. For silver-coated nylon fibers, the actuation performance of TCAMs decreased with the increase of suspension load. Finally, we verify the correctness of the model through experiments. Conversely, the present model can provide theoretical guidance for experimental research and optimized manufacturing of TCAMs.