Fluidic Flexible Matrix Composites for Autonomous Structural Tailoring; Final rept. 1 Oct 2006-30 Jun 2008

摘要

This project develops Fluidic Flexible Matrix Composites (F2MC) and structures that have controllable and reversible stiffness change. F2MC tubes are fiber wound and filled with fluid. If the fluid flows freely in and out of the tube then the stiffness is relatively low. Blocking the fluid flow by closing a valve results in high stiffness. In this investigation, we develop an accurate analytical model to predict and optimize F2MC tube performance and experimentally demonstrate 52 times stiffness change from open valve to closed valve. Tailoring the fiber wind angle and matrix material results in a broad range of open and closed valve stiffness values, indicating the wide applicability of the concept. Flexibility in the tube wall and air entrainment in the fluid are found to limit the maximum stiffness ratio that can be achieved. As a first step to develop variable stiffness structures, we model, design, build, and test a honeycomb-F2MC sandwich structure. This beam structure is cantilevered and demonstrates a three times increase in stiffness to an endpoint load from open valve to closed valve. The project demonstrates that F2MC technology has the potential to impact many applications, including soft robotics, isolation mounts, and morphing aircraft.