Lightweight structures as a subject aims to develop and widen the use of lightweight structures and lightweight materials in order to achieve increased performance for a wide range of structural applications. Performance is conceptualised as a general quantity aiming at both functionality and use in terms of e.g. reduced fuel consumption, environmental impact and life cycle cost. Lightweight structures is a generic but also application-near research area based on material science, structural mechanics, processing and design. The scientific aim is to develop understanding for specific phenomena occurring in these areas, or in the interface between them. New unconventional materials and their use in applications with low weight requirements are specifically studied. Such materials are today especially polymer based fibre composites, wood and cellular materials, i.e. materials that have in common being anisotropic and inhomogeneous.