Date of Award

2020

Degree Type

Thesis

Degree Name

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical, Industrial and Systems Engineering

First Advisor

David G. Taggart

Abstract

Inflatable structures are essential for a wide variety of applications due to their lightweight and high stiffness capabilities. Having a low storage volume, they can quickly be pressurized to produce a rigid and rapidly deployed structure. Due to their increasing popularity, research on air-inflated drop-stitch structures is becoming more common. However, little work has examined liquid-inflated structures. There are unresolved questions about the effect that liquids have on the materials and a lack of engineering data for designing components that are to be pressurized with a liquid.

The objective of this research is to determine the mechanical response of a water-filled drop-stitch inflatable panel. Drop-stitch panels can be manufactured with several different materials and construction methods. The panel evaluated in this research is commercially manufactured with a PVC-laminated, knitted fabric material. Using both air and water to pressurize the panel, inflation tests and three-point bend tests were conducted for each inflation method, then compared. Classical beam theory was used to model beams in three-point bending.

For the inflation tests, average strain values were determined with three-dimensional digital image correlation up to 10 psi. Results show increased strain in the skin when inflating the panel with water. For the three-point bend tests, the panel was tested at 5, 7.5, and 10 psi, and the weight of the water was treated as a uniform load. The theoretical deflection due to superposition of the uniform load and the concentrated mid-span load is compared to the deflection that was obtained experimentally. The results of this research suggest that inflating a panel with water results in a slightly higher bending stiffness as compared to an air-inflated panel.

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