Lifecycle metric integration in lamination parameters design space for structural optimization of variable stiffness composite structures

Weight minimisation is currently the driving factor that determines the lifecycle impact of an aircraft structure. The amount of aircraft that are manufactured yearly is increasing. At the same time, the aviation industry is working on a transition to other energy sources to meet climate goals. This means that the dogma that aircraft structures by definition must have the best possible specific properties, regardless of the specific energy requirement for manufacturing and/or recycling may change. If this happens, the necessity to include lifecycle metrics already in the structural design of composite aircraft parts will increase. In the presented work a method is proposed to include the effect of the specific energy requirement during production already in the design process of a composite plate. The proposed method is applied to a uniaxially compressed plate. Two different composite materials are considered and the results for these materials are compared to a baseline aluminium plate. The energy required to manufacture a plate for both considered composite materials was found to be significantly higher than that of the baseline aluminium plate. The results show that reduced mechanical performance of a composite material can be compensated by adopting variable stiffness laminate design, enabling a weight reduction of up to 35% compared to the aluminium baseline plate. Further study will be required to see whether these results can also be obtained for existing materials and manufacturing processes. Notwithstanding, these first results indicate that the choice of composite materials over aluminium for aircraft structures is to be considered carefully, should the life cycle impact benefit of light-weighting aircraft structures become less dominant in the future.