Ecological lightweight design for sustainable composites: Need for application of frugal engineering principles

Lightweight design is regarded as a technological approach to engineer products in a more energy and material efficient- and, therefore, resource-saving way. In this sense, high-tech multi-materials, also referred to as composites, have become very popular for many decades due to their adaptability of material characteristics as well as high specific mechanical properties. However, composites in particular have also challenging characteristics, for example in the end-of-life of a product, as they cannot be recirculated in a typical material stream, or can only be recycled to a very limited extent (also known as 'downcycling'). Alongside a common product lifecycle, we therefore describe challenges and constraints of ecological lightweight design and underpin the identified issues using semi-structured interviews with experts from the lightweight industry. We further approach the topic through the theoretical lens of frugal engineering, which critically evaluates and reduces the effective features and performances needed for an innovation thus resulting in more affordable and sustainable outcomes. Arguably, frugality might play a decisive role in ecological material transition as technology-driven innovation paradigms in search for the best material are substituted by more use case oriented engineering principles in search for the most suitable material.