Structural behaviour of inflatable PVC fabric cylindrical tubes

Abstract

Inflatable structures are light weight structures that have often been proposed for aerospace applications. They are light in weight, easily manufacturable and foldable. Thus, they can be easily transported and deployed in space. However, the proper characterization for their properties of these structures is still missing. The work done in this paper aims at studying the structural properties of inflatable cylindrical tubes, manufactured from PVC fabric. The cylindrical tubes are fixed as cantilever beams and subjected to a load at the beam tip. Samples of different sizes are tested under different inflation pressures and loads. Load-deflection curves are recorded for each test. Results show that the beam stiffness increases with the increase of inflation pressure and beam cross sectional area. The inflatable beams show linear behaviour up to a certain critical load at which wrinkling occurs. Beyond this load the behaviour of the beam becomes nonlinear and can be unstable. Hysteresis phenomenon is also observed during the unloading of the beam. In addition, Free vibration analysis was conducted to study the effect of inflation pressure on the beam natural frequency. This work is a part of project aiming to design and manufacture an inflatable wind turbine blade to overcome the drawbacks of conventional blades.