Actuation behavior of multi-layer flexible matrix composite tubes with internal pressurization

Flexible composite materials with actuation capabilities are of high interest for use in shapechanging, or morphing, structures. Generally speaking, morphing can be accomplished using a distributed network of actuators designed to deform the host structure. In the current investigation, the use of fluid pressure to actuate multi-layered composite tubes is explored. The tubes were manufactured with filament wound carbon fibers for strength and low modulus polyurethane matrix materials for high anisotropy and deformability. The tubes were made with either one layer for setting a baseline or two layers of differing stiffness for characterizing the actuation capability of the inner tubes embedded inside a relatively stiff structural medium. Both extender and contractor actuators are evaluated. Experiments are devised to characterize the free strain and blocked force capability of the various single and bi-layer specimens. The results demonstrate the ability of the tubes to actuate a surrounding composite material. Blocked force performance was substantially sub-par, potentially due to large end effects in the specimens.