Achieving a Predictive Design for Manufacture Capability in Composites by Integrating Manufacturing Knowledge and Design Intent

近年来，先进复合材料在商用飞机结构中的应用显著增加，例如空客A350 XWB，它们占结构重量的52%。但是，从金属过渡到金属的速度实际上比预期的要慢，尽管先进的复合材料承诺提供能够表现出高强度重量比和高刚度的低重量部件。这种缓慢的吸收主要是由于制造成本高;现在更令人担忧的是，当设计一架新飞机时，机械性能并不是唯一考虑的方面。复合材料必须具有成本竞争力。历史上，民用飞机的设计和制造主要在内部进行，严重依赖人工干预，特别是在组装过程中。这种对人工操作的依赖是由于长时间的开发和持续的飞机设计迭代，这些都使得飞机的大规模生产成本高昂且不可行。在过去的十年中，随着飞机制造商看到更高的销售和吸收，并越来越多地将零件和系统分包给供应商，发生了转变。例如，波音公司将737项目的外包比例从35-50%提高到787项目的70%。虽然这为原始设备制造商（OEM）提供了节省成本的机会，但它给已经受到限制的供应链增加了压力，不仅要交付符合规格的零件，还要缩短时间和降低成本。这也表明了全球工业供应链的低效率，并且越来越需要为中小型供应商量身定制的具有成本效益的制造方法。对于这些公司来说，重新安排工作空间和购买新设备的成本非常有限，特别是如果生产小批量的组件，因为它们可能无法达到盈亏平衡点。为了满足航空航天工业的预期增长和需求，并防止预计的技能短缺，需要开发制造技术，以提高效率，负担得起，并提高质量的一致性。最终目标是第一时间生产出高质量的部件，包括适当的尺寸和性能特性，不仅可重复，而且经济可行。复合材料在二级结构或夹层板中的应用尤其突出。与此相关的复杂几何形状限制了自动化的使用，因此手工铺叠在制造过程中占主导地位。它涉及在几何形状上形成预浸渍布，使其尽可能接近净形状，使用剪切作为主要的面内变形模式。制造中的困难来自几何冲突（由翼型的结构和空气动力学性能施加，导致严格的尺寸公差）;审计跟踪（由OEM施加）;以及它们的低成本开发（公司施加）。这些因素结合在一起，使得飞机复合材料部件总制造成本的大部分都集中在二级结构上，而二级结构的设计和制造过程效率低下，且都是建立在心照不宣的技术和理解基础上的。为了打破这种恶性循环，对于价格关键部件，需要实施低成本制造方法或可制造性设计。这项研究的目标是后者，开发一个新的工具集，能够通知智能设计处理，考虑制造能力更早，并提供设计意图制造功能明确的工作流程指令，使正确的第一次产量。通过这项研究，将开发一种新的复合材料DfM过程，并使收集的信息以简单的格式进行利用，将实现一个基于用户的知识系统。

The use of advanced composites in commercial aircraft structures has significantly increased in recent years through products such as the Airbus A350XWB, where they make up 52% by weight of the structure. But the transition over from metals has actually been slower than anticipated, despite the advanced composites promise of offering lower weight components that are capable of exhibiting high strength-to-weight ratios & high stiffness. This slow uptake is primarily due to the high cost of manufacturing; and is now more of a concern, as when designing a new aircraft the mechanical properties are not the only aspect taken into consideration. Composites must be cost-competitive.Historically, civil aircraft design and manufacturing was largely conducted in-house and relied heavily on manual intervention, especially during assembly. This reliance on manual operations came as a result of long development times and ongoing aircraft design iterations, which together rendered the mass production of aircraft costly and infeasible. In the past decade a transformation has occurred as aircraft manufacturers see higher sales and uptake; and are increasingly subcontracting parts and systems to suppliers. Boeing for example increased their outsourcing from 35-50% for the 737 program to 70% for the 787 program. Whilst this has provided cost saving opportunities for the Original Equipment Manufacturer (OEM), it adds pressure to an already restricted supply chain to deliver parts that are not only made to specification but governed by shortening times and cost reductions. It has also demonstrated supply chain inefficiencies in the global industry, and that the need for cost-effective manufacturing methods tailored for smaller and medium sized suppliers has become more evident.For these companies, the cost of rearranging the work space and of purchasing new equipment is quite restrictive, especially if manufacturing small batches of components, as they may not reach their break-even point. In order to meet the projected growth & demand for the aerospace industry, and guard against projected skills shortages, manufacturing techniques need to be developed to allow for greater efficiency, affordability, and greater consistency in quality. The ultimate goal is to produce high quality components right first time, consisting of the proper dimensions and performance properties that are not only reproducible, but economically viable.Composites usage is particularly dominant in secondary structures or sandwich panels. The complex geometries associated with these restrict the use of automation and so hand layup dominates the manufacturing process. It involves forming a pre-impregnated cloth over a geometry into as near-net shape as possible, using shear as the main in-plane deformation mode. Difficulty in manufacture arises from geometrical clashes (imposed by structural and aerodynamic performance of the aerofoil, resulting in tight dimensional tolerances); audit trails (imposed by the OEM), and; their low-cost development (company imposed). These coalesce such that the majority of the total manufacturing cost for aircraft composite components resides in secondary structures, dependent on inefficient design and manufacturing processes based on tacit skills and understanding.To break this vicious cycle for price-critical parts, either low-cost manufacturing methods or designs for manufacturability need to be implemented. This research targets the latter, developing a new toolset capable of informing for intelligent design processing that considers manufacturing capabilities earlier, and delivering the design intent to manufacturing as functional unambiguous workflow instructions enabling right first time yields. A new process towards composites DfM will be developed through this research, and in enabling gathered information to be exploited in simple formats, a user-based knowledge system will be achieved.