Advanced Continuous Tow Shearing in 3D (ACTS3D): Advanced fibre placement technology for manufacturing defect-free complex 3D composite structures

航空航天产业是英国经济增长的关键部门。英国专门生产最复杂和高科技的飞机零部件，其潜在市场份额估计约为6000亿美元。这一巨大的市场需求也是由环境问题推动的，环境问题要求轻型复合材料飞机结构满足未来的二氧化碳排放法规。自动纤维放置(AFP)过程是支撑英国航空航天工业的核心技术。这种工艺可以使用机器人或计算机控制的龙门机床在三维模具表面高速铺设碳纤维胶带(或丝束)材料，主要用于航空航天工业制造复合材料结构部件，如机身、机翼和支柱。AFP机器能够以不同的速度输送单个丝束，使得丝束中的纤维能够沿着弯曲的路径进行引导，这种纤维引导允许制造具有复杂几何形状的复合材料结构，并实现超越传统直纤维铺设设计限制的超高结构效率。然而，它在纤维转向生产复杂的复合材料部件方面有一些基本的限制。首先，由于AFP机器通过弯曲丝束带来引导纤维，因此总是会产生纤维弯曲缺陷。其次，当铺设在与有限宽度丝束不能完美镶嵌的双曲面上时，它需要经常切割丝束，这也会造成纤维不连续和树脂口袋等缺陷。这种由工艺引起的缺陷是降低生产速度并使航空航天工业的设计过程复杂化的关键障碍。此外，随着复合材料部件的形状变得越来越复杂，在纤维转向过程中将此类缺陷降至最低变得越来越重要。本项目旨在开发一种新的改变游戏规则的纤维贴装技术，该技术可以在基本了解两种材料的浸渍和变形特性的基础上，生产出无缺陷的双曲线复合材料部件。即将开发的新头部机构将能够动态产生可变宽度的丝束，以覆盖复杂3D表面的镶嵌部分，而没有间隙。将有关两级变形特性的科学知识与先进的头部机构以及新的头部控制算法相结合，以实现在复杂三维表面上使用连续丝束剪切机构的无屈曲纤维转向。最后，将在使用所开发的头部控制算法编程的机器人平台上对样机头部进行测试，并将使用各种检测方法来评估铺设质量和精度。这为复杂的3D复合材料部件建立了一种概念验证制造工艺。尽管业界正在通过修改工艺参数或丝束材料来解决质量问题，但现有的AFP技术还没有能够无缺陷地操纵丝束或控制丝束宽度。这一独特的颠覆性AFP工艺的成功开发将为英国航空航天行业提供一个根本解决方案，解决他们面临的质量问题，使英国处于下一代自动化复合材料制造技术的前沿。

The aerospace industry is the key sector for growth of the UK economy. The potential market share of the UK, which is specialised in the most complicated and high tech aircraft parts, is estimated to be around $600 billion. This enormous market demand was also driven by the environmental issue, which requires the lightweight composite aircraft structures to meet the future CO2 emission regulations.The automated fibre placement (AFP) process is the core technology that underpins the UK's aerospace industry. This process can lay up carbon fibre tape (or tow) materials on a three dimensional mould surface using a robotic or a computer-controlled gantry machine at high speed, which is mainly used in the aerospace industry to manufacture composite structural components such as fuselages, wings, and spars. The AFP machine's capability of feeding individual tows at different speeds enables steering the fibres within the tows along curved paths, and such fibre steering allows for manufacturing composite structures with complex geometry as well as realising ultra-high structural efficiency beyond the limit of the conventional straight fibre lay-up design. However, it has a few fundamental limitations in fibre steering to produce complex composite components. First, since the AFP machine steers the fibres by bending the tow tape, fibre-buckling defects are always generated. Second, it needs to frequently cut the tows when laying up on a doubly-curved surface that cannot be perfectly tessellated with the finite width tows, which also creates defects such as fibre discontinuity and resin pockets. Such process-induced defects are a critical barrier that reduces the production speed and complicates the design process in the aerospace industry. Furthermore, as the shape of the composite components becomes more complex, the minimisation of such defects in fibre steering process is getting more important.This project aims to develop a new game-changing fibre placement technology that can produce defect-free doubly-curved composite components, based on fundamental understanding of the impregnation and deformation characteristics of tow materials. The new head mechanism to be developed will be capable of producing variable width tows on-the-fly to cover tessellated sections of a complex 3D surface without gaps. The scientific knowledge on tow-level deformation characteristics will be integrated with an advanced head mechanisms as well as a new head control algorithm in order to realise the buckling free fibre steering using the continuous tow shearing mechanism on complex 3D surfaces. Finally, a prototype head will be tested on a robotic platform programmed using the developed head control algorithm, and the lay-up quality and accuracy will be evaluated using various inspection methods. This establishes a proof-of-concept manufacturing process for complex 3D composite components.Although the industry is making various attempts to solve the quality problems by modifying the process parameters or the tow material, there are no existing AFP technologies that can either steer the tow without defects or control the tow width. The successful development of this unique and disruptive AFP process will provide the UK aerospace industry with a fundamental solution to the quality problems that they are facing, which enable the UK to be at the forefront of next-generation automated composites manufacturing technology.