The application of composites has been increasing dramatically in aerospace structures recently, for example, composites have contributed over 50 percent of the structure mass of large transport airplanes Boeing 787 and Airbus 350XWB. However, the further usage has been restricted because of the high material and manufacturing costs. Hence, it is essential to utilize cost estimation tools for accurate cost estimation in the early design stages, and then efficient decisions and design optimizations could be made to reduce the cost of composite products. This research project aims to develop a cost model for aerospace carbon fibre reinforced plastic (CFRP) composites, which will help designers and cost engineers with the cost estimation for composites manufacturing in the early development stages. The main objectives of the research are to: (i) recognise the standard manufacturing stages and activities of CFRP components; (ii) identify the cost drivers of composites manufacturing; (iii) identify the cost estimation relationships; (iv) develop a cost model that can assist designers and engineers with manufacturing cost estimation for CFRP components; (v) validate the developed cost model through case studies and expert judgements. The process of model development was carried out through four main steps: firstly, conducting an integrated understanding of cost modelling for composites manufacturing; secondly, collecting data for cost modelling from industry and existing literature and databases; thirdly, developing the cost model with several function modules and databases; and finally, taking a validation of the developed model. The developed cost model consists of several modules: material selection, process planning, cost estimation, cost reporting and a user friendly interface. Moreover, the selection and planning modules are combined with databases including material and process. The developed model enables the user to estimate the manufacturing cost and process time of CFRP composites, and it can also help designers realize the impact of design changes on the manufacturing cost. The process planning can efficiently help estimators with manufacturing process understanding and accurate time estimation. Quality control activities are time consuming and investment sensitive in composites manufacturing.

Manufacturing methods for aerospace composite parts are various. Vacuum assisted resin transfer moulding (VARTM) is one of the common methods. It requires manual draping of fabrics to produce preforms. The cost and quality of this method depend on the draping strategy, which is the sequence of draping operations performed by staff as they lay fabrics on moulds. These sequences can be very numerous with many possible starting points, yarn orientations, and fabrics used. In this group project, a predictive software tool is designed ultimately to identify the best draping strategy to reduce cost and improve quality in producing preforms. Generation of preform flat patterns for the CNC cutting tables, and of plybooks for providing instructions to shop floor staff, are developed and integrated into the predictive tool so that the manual draping process can potentially be conducted under the best draping strategy. The work presented in this thesis details the solutions for finding flat patterns for the best draping strategy for the CNC cutting tables, and the generation of plybooks for providing instructions to shop floor staff. The work is organized into four main parts: developing flattening algorithms for three types of base surfaces (BaS) defined in this project, developing a subsequent stitching algorithm aimed at stitching individual flattened BaS into a unified flat pattern for a given mould, lab validations to assess the proposed flattening and stitching algorithms, and establishing the capability to generate instruction .DXF files and plybooks for any received draping strategy. These algorithms are integrated into the predictive tool to facilitate manual draping processes under the optimal draping strategy.

Há um aumento da demanda mundial por materiais de alto desempenho, e os compósitos encaixam-se perfeitamente nesse nicho por serem resistentes e leves. Os compósitos poliméricos são feitos a partir da mistura de resina e reforço, no entanto, existem diversas metodologias para fazê-la. O presente trabalho compara em amplo aspecto, três desses métodos: laminação manual, infusão de resina e pré-impregnado. O primeiro é o método mais simples, o segundo é utilizado principalmente pela indústria náutica, e o terceiro pela indústria aeroespacial. Foram realizados diversos ensaios mecânicos como tração, flexão, cisalhamento, impacto, entre outros, e os resultados foram comparados entre si para demonstrar qualitativamente e quantitativamente as diferenças entre eles. Este trabalho demonstrou que o processo de pré-impregnado produz peças com propriedades cerca de 30% melhores que a infusão de resina, que por sua vez, possui um acréscimo de 25% sobre as propriedades da laminação manual. / There is an increasing worldwide demand for high performance materials, and therefore the composites reach a prominent position for being resistant and light weighted. Polymeric composites are made from mixing a given resin and the fibre; however, there are several different methodologies to do so. This work intends to compare, in a wide array, three of those methods: hand lay-up, resin infusion under flexible tooling and pre-pregs. The first is the simplest of all, the second is mainly used by the marine industry, and the third by the aerospace industry. Several mechanical tests such as tension, flexural, shear, impact, among others, were performed and their results were compared to infer their qualitatively and quantitatively differences. This study shows evidence that pre-preg properties are about 30% better than resin infusion, and the last has 25% better properties than hand lay-up.

Há um aumento da demanda mundial por materiais de alto desempenho, e os compósitos encaixam-se perfeitamente nesse nicho por serem resistentes e leves. Os compósitos poliméricos são feitos a partir da mistura de resina e reforço, no entanto, existem diversas metodologias para fazê-la. O presente trabalho compara em amplo aspecto, três desses métodos: laminação manual, infusão de resina e pré-impregnado. O primeiro é o método mais simples, o segundo é utilizado principalmente pela indústria náutica, e o terceiro pela indústria aeroespacial. Foram realizados diversos ensaios mecânicos como tração, flexão, cisalhamento, impacto, entre outros, e os resultados foram comparados entre si para demonstrar qualitativamente e quantitativamente as diferenças entre eles. Este trabalho demonstrou que o processo de pré-impregnado produz peças com propriedades cerca de 30% melhores que a infusão de resina, que por sua vez, possui um acréscimo de 25% sobre as propriedades da laminação manual. / There is an increasing worldwide demand for high performance materials, and therefore the composites reach a prominent position for being resistant and light weighted. Polymeric composites are made from mixing a given resin and the fibre; however, there are several different methodologies to do so. This work intends to compare, in a wide array, three of those methods: hand lay-up, resin infusion under flexible tooling and pre-pregs. The first is the simplest of all, the second is mainly used by the marine industry, and the third by the aerospace industry. Several mechanical tests such as tension, flexural, shear, impact, among others, were performed and their results were compared to infer their qualitatively and quantitatively differences. This study shows evidence that pre-preg properties are about 30% better than resin infusion, and the last has 25% better properties than hand lay-up.