Evaluation of an Inflated Beam Model Applied to Everted Tubes
This work provides validation for modeling everted tubes in engineering applications, but it is incremental as it builds on existing inflated beam models.
This paper validated the assumption that everted tubes can be modeled as inflated beams by comparing tip deflections and buckling conditions of everted and uneverted beams under transverse loads, finding everted beams buckled at 83% of theoretical conditions while straight beams collapsed at 109%.
Everted tubes have often been modeled as inflated beams to determine transverse and axial buckling conditions. This paper seeks to validate the assumption that an everted tube can be modeled in this way. The tip deflections of everted and uneverted beams under transverse cantilever loads are compared with a tip deflection model that was first developed for aerospace applications. LDPE and silicone coated nylon beams were tested; everted and uneverted beams showed similar tip deflection. The literature model best fit the tip deflection of LDPE tubes with an average tip deflection error of 6 mm, while the nylon tubes had an average tip deflection error of 16.4 mm. Everted beams of both materials buckled at 83% of the theoretical buckling condition while straight beams collapsed at 109% of the theoretical buckling condition. The curvature of everted beams was estimated from a tip load and a known displacement showing relative errors of 14.2% and 17.3% for LDPE and nylon beams respectively. This paper shows a numerical method for determining inflated beam deflection. It also provides an iterative method for computing static tip pose and applied wall forces in a known environment.