Travelers don’t always think about flooring while boarding a plane and looking for their seats because they expect the floor to be sturdy and supportive. A team of plucky students decided to investigate the sandwich composite structure for airplane flooring using digital image correlation (DIC) with their project, Investigation of Core Configuration on Bending Strength in Sandwiched Composites. The winning solids team included Flavius Penescu, Marshall Williams, Aiden Wilson, and Ben Zabriskie, all fourth-year undergraduates.

“Many teams wanted to do fluids, so we chose solids. We wanted to be competitive in the process and differentiate ourselves, so we decided to use DIC. DIC is an image-based method allowing to measure strains and deformation, which is necessary for the design of more reliable aircraft,” said Williams, who plans to go into consulting after he graduates in the spring.

The team created a sandwich composite for airplane flooring using two steel sheets and foam. They attached two thin and stiff sheets to a lightweight, thick foam core. The material the team chose would be ideal for something like cargo plane flooring or wing materials. Therefore, this experiment explored how different core configurations of that middle piece in between the two steel plates affected the sandwich material bending stiffness relative to its weight. They measured it by the ratio of the bending stiffness of the material to its weight.

They analyzed the data from the DIC setup, which essentially tracks the movement of surface features during the experiment. This data, upon ‘special’ processing provides the strain maps that are developed in the sandwich material upon the application of an external force. From the experimentally obtained strain maps, they calculated the flexural stiffness and, eventually, the stiffness-to-weight ratios of each specimen.

“We experimented with drilling holes or cutting out certain patterns because, in theory, that would remove weight. Since the steel sheets weigh more than the foam, cutting out those holes made no significant decrease in the weight and significantly decreased the bending stiffness. So, we found that the solid flooring piece was the most effective,” Williams said.