MECHANICAL RESPONSE OF POLYMER-FABRIC SKIN MATERIALS USED IN INFLATABLE DROP-STITCH STRUCTURES

Abstract

The rapid deployment capabilities of drop-stitch inflatable structures is of increasing significance for aerospace, naval, and military applications. The drop- stitch inflatable structures have a high load capacity, low manufacturing cost, low weight, and low storage volume. These properties make such inflatable structures ideal for applications where the rapid deployment of structures is crucial, such as in aerospace, naval, and military applications. The rigidity of such structures increases with the inflation pressure of the structure and is dependent on the properties of the composite neoprene-fabric skin material. The objective of this research is to determine the mechanical response of the composite neoprene-fabric material used in drop-stitch inflatable structures under uniaxial loading such that a more accurate model for the mechanical behavior of inflatable woven fabric drop-stitch composite structures may be developed. This research utilizes digital image correlation (DIC) techniques in order to noninvasively measure the behavior of the skin material under uniaxial loading. The behavior of an inflatable drop-stitch panel under four-point bending is analyzed and compared to theoretical results using the experimentally calculated properties of the skin material. The deformation due to bending and shear are both calculated and compared to the experimental data. Additionally, an empirical parameter is introduced to the classical beam theory equation for panel de under four-point bending in order to account for kinking of the panel at the load points. The results of this research found the relevant properties of the skin material which are used in the panel modeling. The comparison of the four-point bending model and experimental data demonstrated that the classical beam theory is not sufficient for modeling drop-stitch inflatable structure behavior, especially at low internal pressure. The shear deformation and deformation mechanics of the drop- stitch inflatable structures were found to be significant to the overall mechanical response of the panels.