Virtual Testing of Additively-Manufactured Hybrid Metal-Composite Structures

Additive Layer Manufacturing (ALM) has the potential to revolutionise the design and manufacture of hybrid joints by enabling tailored metal-composite interfaces that promote the optimal load transfer between metal and fibres. This will enable high-performance / high-endurance hybrid structures which can be manufactured via 'co-curing' processes, i.e. consolidation in a single step without the need for secondary adhesive bonding. However, in order to achieve optimal designs a high-fidelity modelling strategy is necessary.

This project will develop and validate modelling strategies to:
1. Predict the detailed meso-scale structure of hybrid metal-composite materials after manufacture and consolidation, including local fibre orientation with respect to metallic surface protrusions. These methodologies will be validated against micro-CT scans of real specimens.
2. Resolve stresses at the level of individual tows/yarns and protrusions, accounting for thermal residual stresses and stresses due to externally applied loads. These data will provide an initial measure of the quality results can be used in the development of load path-based optimisation at the micro- or meso-scale levels
3. Analyse joint strength and damage/fracture propagation properties due to combinations of quasi-static, impact and cyclic loading. Validate the methodologies against mechanical tests on real specimens.


In a broader sense, this research introduces two new concepts for the design of hybrid metal-composite structures, namely:
1. Performance-driven design, with performance being evaluated at the level of individual material constituents (i.e. fibres, matrices and metals), considering realistic micro-structures obtained via in-depth knowledge of the manufacturing process.
2. Enabling the optimisation of damage tolerant designs where the objective measure of performance is related to both damage initiation and evolution. Due to time and resource constraints this First Grant research will enable the development of the virtual testing capability only, while the development of a closed-loop optimisation technique will be the focus of future work.

This research falls within the EPSRC "Engineering" theme in the area of "Materials Engineering - Composites", which is classified by a "Maintain" research action. EPSRC has made a number of large investments in this area in recent years, including the establishment of the National Composites Centre near Bristol, and the opening of one CDT as well as one IDC at the University of Bristol. Cardiff University has strong collaboration links with the Advanced Composites Centre for Innovation and Science (ACCIS) who are supporting this application (Prof Stephen Hallett, see Track Record). This project will contribute to strengthening these links while developing a new topic of research for Cardiff University which will help raise its research profile on the analysis of composite materials and structures.
The outcomes of this research may have a direct impact on some of the design and manufacturing conducted by the aerospace industry, especially in civil aviation. The UK aerospace industry is very important for the economy of the country. According to the UK Trade and Investment Agency "The UK has the second largest aerospace industry in the world after the US, with over 3,000 companies employing about 230,000 people". By helping to develop innovative manufacturing techniques for aerospace structures, this research would also be contributing to this success story.
With composite materials being such a key area of expertise for British scientists and industrialists, and being so deeply rooted in UK's important aerospace industry, it is expected that research in the area of "Materials Engineering - Composites" will remain a priority for EPSRC and other funding bodies also in the foreseeable future.