Development and Evaluation of Stitched Sandwich Structures

University Of Utah, Salt Lake City UT

Investigators

Abstract

An exploratory research program is planned to develop and assess through the thickness stitching of composite sandwich structures. We will explore the feasibility and potential benefits obtained by stitching foam core sandwich panels with Kevlar yarns. To offer low cost manufacturing, we propose to manufacture stitched sandwich panels using low-cost, out-of-autoclave processing. Sandwich panels will be stitched in a dry perform state, vacuum bagged, and infiltrated using Vacuum Assisted Resin Transfer Modeling (VARTM) processing. The through-the-thickness stitches will provide resin infusion paths to the facesheet adjacent to the tool surface. Evaluation will focus initially on performing standardized ASTM tests on the stitched sandwich panels and comparing results with comparable unstitched panels. Additional specialized tests will be performed to evaluate the increase in damage tolerance provided by the Kavlar stitched. Finally. We will explore finite element based analysis methodologies that may be used to design optimized stitching configurations for specific applications. If we are successful in this exploratory research, we will demonstrate that stitched sandwich structures offer a significant increase in damage tolerance and interlaminar strength while allowing for low cost processing.