Experiments on Cross-Sectional Deformation of Inflatable Tubes Under Bending Loads

Abstract

The detailed experiments on cross-sectional deformation of inflatable tubes are examined experimentally to introduce a simple mathematical model of the inflatable tubes under bending loads. The pure bending environment experiments are performed with four-point bending experiments on the LDPE tubes. The effects of bending load and inflation pressure on the cross-sectional deformation, collapse location and area, are measured experimentally. Using the experimental results, a simple mathematical model are introduced. Many research works on the inflatable structures have been performed to apply the large deployable space structures. The inflatable tubes are expected to be one of the primary structural elements for constructing the space structures. The structural properties of the inflatable tubes are complicated due to the thin wall flexible membrane materials of the tubes, and thus, the several recent research works examine the structural properties using precise finite model. On the other hand some theoretical approaches to investigate the structural properties of the inflatable tubes are performed by Comer 1 , and Main 2 . These researches are based on the assumption of uniform circular cross-section configuration after collapsing the inflatable tubes. However, the cross-sectional deformations are sensitive to evaluate the structural properties of the inflatable tubes in detail. Sakamoto 3 introduced the effects of cross-sectional deformation into the numerical analyses. Only a few experimental research work investigates the cross-sectional deformation of inflatable tubes. Thus, this paper examines the detailed cross-sectional deformation experimentally. At first, the pure bending environment experiments are performed with four-point bending experiments on the LDPE tubes using four-point bending experiments on the tubes. The effects of bending load and inflation pressure on the cross-sectional deformation, collapse location and area, are measured experimentally. Finally a simple mathematical model are introduced using the experimental results.