Preface to the theme issue 'Durability and ageing of composite materials'.

The issue focuses on ageing and durability of composite materials for industrial applications. Ageing and durability are two fundamental topics within the context of design and optimization of materials and structures: ageing may induce degradation and leads to premature failure. Therefore, understanding the main ageing mechanisms is of paramount importance for predicting material durability. These topics are still barely studied systematically and the main related issues are debated within mechanical, chemical, and solid-state physics research communities. This issue aims to update the current research state of the art, clarifying the interplay between chemical and physical mechanisms involved in degradation processes, and providing test protocols and design rules that account for ageing and durability. This article is part of the theme issue 'Ageing and durability of composite materials'.