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

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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.