Closing Material Cycles Through Reverse Engineering Approach—Monomaterial Helmet Made From PLA

ABSTRACT

The end‐of‐life scenario of a product is largely determined during the design phase. To identify potential for improvements in product‐level circularity while considering not only ecological but also economic aspects, a reverse engineering approach is introduced and applied to a bicycle helmet. The stepwise methodology analyzes a conventional helmet composed of six different polymers and one metal and quantifies both life cycle costs and CO ₂ emissions. Due to the inseparable joining of different materials, the multi‐material helmet must undergo thermal recovery at the end of its life. Using the reverse engineering method, barriers to circularity are systematically identified and alternative design strategies are derived. The resulting solution, a mono‐material helmet made of PLA, enables mechanical recycling at the product's end‐of‐life. Final quantification shows that the mono‐material helmet achieves a 30.33% improvement in economic performance, a 54.01% reduction in environmental impact (measured via Life Cycle Assessment), and a 27% reduction in the circularity gap (assessed through the Life Cycle Gap Assessment). These results highlight the potential of reverse engineering to drive sustainable product design by aligning environmental and economic objectives.