Development and Evaluation of Stitched Sandwich Structures

拟开展一项探索性研究项目，对复合材料夹层结构的厚度拼接进行开发和评价。我们将探讨用凯夫拉纱缝制泡沫芯夹芯板的可行性和潜在效益。为了提供低成本的制造，我们建议使用低成本，非高压釜加工制造缝缝夹芯板。夹层板将在干燥状态下缝合，真空装袋，并使用真空辅助树脂转移建模（VARTM）加工渗透。贯穿厚度的缝线将为靠近工具表面的面板提供树脂注入路径。评估最初将侧重于对缝合的夹层板进行标准化的ASTM测试，并将结果与同类未缝合的面板进行比较。将进行额外的专门测试，以评估Kavlar缝合线提供的损伤容忍度的增加。最后。我们将探索基于有限元的分析方法，可用于为特定应用设计优化的拼接配置。如果我们在这项探索性研究中取得成功，我们将证明缝合夹层结构在允许低成本加工的同时，显著提高了损伤容限和层间强度。

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.