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

近年来，通过空中客车A350XWB等产品，先进复合材料在商用飞机结构中的使用显著增加，按重量计算，先进复合材料占结构的52%。但是，从金属向金属的过渡实际上比预期的要慢，尽管先进的复合材料承诺提供更轻的部件，这些部件能够表现出高强度/重量比和高刚度。这种缓慢增长的主要原因是制造成本高；现在更令人担忧的是，在设计新飞机时，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。从历史上看，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漫长的开发时间和持续的飞机设计迭代的结果，这些共同导致大规模生产飞机的成本高且不可行。在过去十年里，随着飞机制造商看到更高的销售额和接受度，并越来越多地将零部件和系统分包给供应商，这种转变已经发生。例如，波音公司将737项目的外包比例从35%-50%增加到了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，但它也增加了本已受限的供应链的压力，要求交付不仅按规格制造的部件，而且要缩短时间和降低成本。这也证明了全球行业的供应链效率低下，为中小型供应商量身定做具有成本效益的制造方法的必要性已变得更加明显。对这些公司来说，重新安排工作空间和购买新设备的成本相当有限，特别是如果制造小批量零部件，因为它们可能达不到盈亏平衡点。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，以实现更高的效率、可负担性和更高的质量一致性。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，不仅可重复使用，而且具有经济可行性。复合材料在二次结构或夹芯板中的使用尤其占主导地位。与此相关的复杂几何形状限制了自动化的使用，因此手工堆积在制造过程中占据主导地位。它包括使用剪切作为主要的面内变形模式，在几何体上将预先浸渍的布料形成尽可能接近净形状的形状。制造上的困难来自于几何冲突(由机翼的结构和气动性能造成的，导致尺寸公差较小)；审核跟踪(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的总制造成本的大部分存在于二次结构中，依赖于基于默契和默契的低效设计和制造过程。要打破价格关键部件的这种恶性循环，要么需要实施低成本制造方法，要么需要实施可制造性设计。这项研究的目标是后者，开发一种新的工具集，能够为更早考虑制造能力的智能设计处理提供信息，并将设计意图作为功能明确的工作流指令传递给制造，从而实现正确的第一时间产出。通过这项研究，将开发一种新的复合材料DFM过程，并使收集的信息能够以简单的格式得到利用，从而实现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.