One size doesn't fit all: an approach to progress delivery of sustainability for the composites industry

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The habitat which we as humans call home is changing as a result of our actions. Decades of un-checked economic growth starting with the industrial revolution are damaging the planet. As engineers and scientists, we have the capability to reduce the impact humankind is having and move towards a sustainable or even better, regenerative lifestyle. Composite materials with their energy intensive productive methods, complicated end of life processing and wasteful manufacturing processes have hurdles to overcome in reducing their environmental impact. The challenge of sustainability lies in how to quantify what drives a given design to be sustainable and does it forgo functional performance or imply significant financial cost in being so.Life Cycle Engineering (LCE) is a means of assessing the performance of designs or materials, considering the whole life cycle, against economic, environmental and technical factors. It has seen relatively little application to composites case studies, especially for marine industry. Furthermore, iterative design approaches that move beyond simple materials selection diagrams, instead utilising for instance optimisation algorithms, have been seldom seen. This thesis first implemented an Particle Swarm Optimisation (PSO) algorithm which embodies LCE to enable quantification of a given application's holistic performance against economic, environmental and technical criteria. Through a selection process of the solutions from the Pareto front, the process allowed for an optimised design to be found, for a given application and set of subjective weighting criteria.Materials were selected to build a database to assess the three LCE criteria. Glass, basalt and flax fibres were selected with epoxy, bio-epoxy and Elium (registered TM) resins. The selected materials were characterised to generate the required data against economic, environmental and technical factors. Economically, on a per kg basis glass composites had the lowest life cycle cost, followed by basalt and finally flax. Environmentally, on a per kg basis, basalt and Elium (registered TM) had the lowest environmental impact, due to the low impact of fibre production and the low energy requirement during the manufacturing process. Flax and epoxy was found to have highest environmental impact, due to the high impacts associated with the spinning of flax fibres and the high energy requirement from production of epoxy constituents. Technically, at approximately the same areal weights, basalt fibre composites had a significantly higher tensile stiffness and strength than glass and even more so than flax. In shear testing, glass composites were superior, with basalt close behind and flax the lowest.The data was then used to design and manufacture a marine industry demonstrator. Using the previously generated data with the algorithm, it was found that basalt and Elium (registered TM) was the optimised solution when environmental and technical factors are given preference over economic factors. Glass and epoxy was the choice for a 'business-as-usual' scenario, where economic and technical factors are preferred to environmental considerations. Basalt composites dominated the design space where economic factors were not given significant weighting, with glass composites dominating the space where they were.This work demonstrated that, for one application, basalt composites are the optimised solution where environmental factors are prioritised. Furthermore, it has demonstrated a methodology which should be used for assessing what the most 'sustainable' solution is for further applications. The work represents a first step in what will hopefully instigate further work assessing what is the most sustainable design for a plethora of other case studies. For only if such case studies are considered, will there be truth around what forms designs must take to tackle the climate crisis.