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Novel Tow Termination Technology for High-Quality AFP Production of Composite Structures with Blended Ply Drop-offs

用于高质量 AFP 生产混合层脱落复合结构的新型丝束终止技术

基本信息

批准号：
EP/P027288/1
负责人：
ByungChul (Eric) Kim
金额：
$ 12.88万
依托单位：
University of Bristol
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FP027288%2F1
关键词：
Novel Tow Termination Technology Quality

项目摘要

The automated fibre placement (AFP) process is a cutting-edge technology to manufacture complex composite aerospace structures, which was first developed in the early 1980s. This process lays down a set of pre-impregnated carbon fibre tapes called 'slit tape' or 'tow' following designed paths on a 3D surface. Despite increasing demands for the fibre placement technologies, the process-induced defects in fibre placement process are critical problems that need to be solved so as to guarantee the quality and structural reliability of composite aircraft components. Those defects mainly result from the limitations of the modern AFP machines.One of the major limitations is that they always generate resin pocket defects when producing composite components with thickness variation by terminating the tows inside the laminates. The conventional guillotine tow cutting mechanism, which almost all modern AFP machines are adopting, creates stepped tow ends when cutting the tows. Although the tow thickness is quite small (~0.12 mm), empty gaps are produced when the next ply covers the ends due to the high bending stiffness of the carbon fibres. The gaps are filled with resin matrix after a curing process, and act as crack initiation points under loading. This is an example how a manufacturing limitation can increase the design complexity and manufacturing cost. This provokes complex design problems to optimise the tow termination locations considering their detrimental effects on the structural performance, which significantly delays the design process and increases the design cost. The conventional approaches dealing with these defects have been mainly about how to quickly and accurately predict their detrimental effects on the structural performance and take them into account in the design stage. However, this project aims to provide an inventive solution to eliminate those defects by tackling the fundamental weaknesses of the concept of modern AFP machines, which is a tow scarfing mechanism that can taper the tow ends when the machine terminates the tows during the automated lay-up process. This novel mechanism, which has never existed before, will allow for eliminating the resin pocket defects in automated manufacturing of composite aircraft components, ensuring high quality and reliability of the end products. At the same time, the design process as well as the post-performance evaluation process can be shortened and simplified by removing the effort to take into account the process-induced defects. The objectives of this project are not only for developing a new mechanism but also for providing fundamental understanding of the mechanics in tow cutting process and how the geometry of the terminated tow end affects the internal load transfer and failure mechanism. This project is ultimately for establishing a design guideline supported by experimentally validated data to effectively use the advantages of the new tow termination method.

自动纤维铺放（AFP）工艺是制造复杂复合材料航空航天结构的前沿技术，最早发展于20世纪80年代初。该过程在3D表面上沿着设计的路径铺设一组预浸渍的碳纤维带，称为“狭缝带”或“丝束”。尽管对纤维铺放技术的要求越来越高，但纤维铺放过程中的工艺缺陷是保证飞机复合材料构件质量和结构可靠性需要解决的关键问题。这些缺陷主要是由于现代AFP设备的局限性造成的，其中一个主要的局限性是，它们在生产具有厚度变化的复合材料部件时，通过将丝束终止在层压板内，总是产生树脂袋缺陷。几乎所有现代AFP机器都采用的传统断头台丝束切割机构在切割丝束时产生阶梯状丝束端部。虽然丝束厚度非常小（约0.12 mm），但由于碳纤维的高弯曲刚度，当下一层覆盖端部时会产生空间隙。固化过程后，间隙被树脂基质填充，并在负载下充当裂纹萌生点。这是制造限制如何增加设计复杂性和制造成本的示例。这引发了复杂的设计问题，以优化牵引终止位置，考虑其对结构性能的不利影响，这显著延迟了设计过程并增加了设计成本。处理这些缺陷的传统方法主要是如何快速准确地预测它们对结构性能的不利影响，并在设计阶段将其考虑在内。然而，该项目旨在提供一种创造性的解决方案，通过解决现代AFP机器概念的根本弱点来消除这些缺陷，该机器是一种丝束烧剥机构，当机器在自动铺叠过程中终止丝束时，该机构可以使丝束端部变细。这种以前从未存在过的新机制将允许消除复合材料飞机部件自动化制造中的树脂袋缺陷，确保最终产品的高质量和可靠性。同时，设计过程以及后性能评估过程可以缩短和简化，消除努力，以考虑过程引起的缺陷。本项目的目标不仅是开发一种新的机制，但也提供了基本的理解，在丝束切割过程中的力学和终止丝束端部的几何形状如何影响内部负载传递和故障机制。该项目的最终目的是建立一个由实验验证数据支持的设计指南，以有效地利用新的拖曳终止方法的优点。