Date of Award

2019

Degree Type

Thesis

Degree Name

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical, Industrial and Systems Engineering

First Advisor

David G. Taggart

Abstract

Due to the rising demand in lightweight and rapid deployable structures, inflatable drop-stitch structures are gaining importance. Despite the increasing interest in these structures, no reliable models to predict the behavior of the panels are available and the effects that lead to a pressure dependent stiffness are not fully understood.

In this research, classical lamination theory is applied to obtain homogenized engineering constants for the composite skin for use in predicting the panel response. In the next step, a finite element model of an inflatable drop-stitch panel under a four-point bending load is developed and the simulation results are validated by the comparison to experimental data. In addition, the simulation is used to validate the analytical model derived in a recent study (Smith, Michael 2019). An analytical model for the stress distribution within the panel is presented and compared to the numerical simulation results.

It is determined that the application of the classical lamination theory to predict skin properties is very sensitive to the orthotropic properties of the constituent layers. Obtaining good correlation with experimental data requires some minor adjustment of layer properties. The finite element simulation of a four-point bending test of an inflated drop-stitch panel showed that although the model does not correlate exactly with the experimental results, it does provide a reasonably good estimate of the panel response. The numerical model also provides a tool to evaluate the effects of various deformation mechanisms on the overall response. It is determined that the pressure dependent stiffness is associated with nonlinearities of the model.

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