Modeling and Analysis of Interfiber Compaction Effects in FMC Actuators for Bio-Inspired Applications

Recently, flexible matrix composite (FMC) actuators were employed in a robotic fish for swimming [1]. The FMC actuators based on flexible matrix composites developed by Philen et al. [2] are pressure driven muscle-like actuators capable of large displacements as well as large blocking forces. The FMC actuators can also exhibit a large change in stiffness through simple valve control when the working fluid has a high bulk modulus [3, 4]. Several analytical models have been developed that capture the geometrical and material nonlinearities, the compliance of the inner liner, and entrapped air in the fluid [2, 4, 5]. But no work has been performed in capturing the fiber compaction in the composite laminate, which can have significant influence on the closed valve FMC stiffness. Therefore the objective of this research is to expand upon the previously developed models and incorporate compliance between the woven fibers.