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Influence of Stitch Parameters on the Fracture Energy of Stitched Sandwich Composites
Abstract
The influence of stitch density, linear thread density, and facesheet thickness on the fracture energy of stitched sandwich composites was investigated using a design of experiments approach. Sandwich composites are composed of two rigid facesheets that are bonded to a lightweight core. The separation of facesheets produces a high flexural stiffness that is typically needed for flight-control surfaces in aerospace applications. These structures can develop facesheet-to-core separation under relatively low out-of-plane loads due to their low interfacial properties between the constituents. In this study, sandwich composites were manufactured with through-thethickness reinforcements, or stitching, to act as crack-growth inhibitors. Stitched sandwich composites were manufactured with various treatment combinations of stitch density, linear thread density, and facesheet thickness. Single cantilever beam tests were performed to estimate the mode I fracture energy. A response surface model based on a face-centered design of experiments approach was developed to investigate the selected factors, and their interaction, on the mode I fracture energy. Unique fracture surface morphologies are exhibited during mode I testing that are dependent on stitch processing parameters. The results indicate that stitching is an excellent candidate to inhibit crack growth.
DOI
10.12783/asc35/34963
10.12783/asc35/34963