Meta-material adhesives for improved performance and functionalisation of bondlines

Sustainable development goals are formulated within European policies aiming at a sustainable, and yet competitive, circular economy. Most recently, in the Communication on the European Green Deal, the European Commission committed to the adoption of a new Circular Economy Action Plan to accelerate and continue the transition towards a circular economy. This commitment is heavily reflected in novel approaches to materials science, production, and development, and it is driven by technologies such as emerging additive manufacturing. There are two critical fronts in which the development of new materials' technologies will play a decisive role in shaping this much needed green transition; the development of advanced materials whose manufacturability strikes an optimal balance between high demands for functionality, and the improvement of sustainability in the production chain. Focus on the functionality in its own right, e.g., in materials for the transport, construction and energy generation industries, together with unprecedented need for better, cheaper, and sustainable materials is timely. However, maintaining or further increasing the performance and reliability of existing materials, including lightweight composite materials, metal alloys or ceramics, presents challenges at the heart of this current paradigm. For many applications joining similar or dissimilar materials is indispensable, while adhesive bonding is an attractive alternative to classical joining methods, leading to new composites with more functions, and better mechanical and physical performance.

Bonding processes and adhesives are used in a wide range of engineering structures for primary and secondary bonding. However, certain unresolved questions remain open regarding the exploitation of the potential of adhesive bondlines to truly contribute to the development of sustainable engineering structures-those promoting prevention, reuse and repurposing of structural components. This research project proposes to deal with these unresolved questions and to recommend innovative material and structural concepts, new modelling techniques, and novel experimental methods for sustainable structural bonding. The project has multiple objectives, necessitating an interdisciplinary approach for addressing each one of them. The main goal is to exploit the concept of Mechanical Metamaterials within the framework of adhesive bonding and to develop solutions for architected and tuneable bondlines, namely "meta-adhesives". The "meta-adhesive" concept will be investigated by implementing well designed metamaterial lattices into the adhesive bulk. The investigation will span in several scale levels, from the material to the structural component and will respond to specific basic research questions such as: (i) whether the metamaterial scaling properties affect the bondline fracture toughness in a predictable manner; (ii) how the features of failure (from geometrical to material failure) will be affected and how load transfer will be influenced by having architected bondlines; (iii) in which manner and to what extent can the meta-adhesive bondline be functionalised in order to serve the aforementioned prevention/reuse and repurposing for improved sustainability in structures.

This fellowship will allow the applicant to use and expand his knowledge in the field of Mechanical Metamaterials to deal with unresolved questions and to recommend innovative material and structural concepts, new modelling techniques, and novel experimental methods for sustainable structural bonding.