Tailored Fluidic Composites for Stiffness or Volume Change

An analytical model of a composite structure consisting of an F²MC tube embedded in epoxy is used to study the impact of confining structural media on the ability of F²MC tubes to pump fluid and change stiffness. The surrounding stiff epoxy reduces the performance relative to an isolated F²MC tube, but this disadvantage can be minimized by tailoring the tube wall thickness and fiber angle. The composite can pump 250 times more fluid than a piston of the same diameter if the F²MC tube has a thick shell wall and a near-axial fiber orientation. With a moderately thick wall and low fiber angle, the closed valve axial stiffness can be increased by a factor of 2.2 relative to the open valve stiffness. The maximum pumping factor and modulus ratio, however, are 80% and 2.6% of the F²MC tube without the surrounding epoxy.