Abstract
The continuous requirements in terms of carbon emission reduction lead to the need for lighter and more efficient structures in the automotive, railways, aeronautical and in general in the transport field. In turn, the higher requirements in terms of efficiency lead to the tailoring of the materials to be employed. Different materials are needed to fulfil different functions in the same assembly and the connections between metals and composite materials are increasingly common. At the same time, the design flexibility and the latest developments of the Additive Manufacturing (AM) techniques, open new scenarios for better exploitation of the material properties. In [1] it is stated that “Parts combining 3D printed metals with reinforced polymers, have a great potential to tackle industrial challenges such as light-weighting, reducing costs and improving part performance, especially for sectors such as automotive, but also aerospace and beyond”. However, the joining between metals and composites could represent a weak point of the components compromising their reliability. The first part of this project is therefore aimed at the development of interfacial 3D open structures obtained by additive manufacturing on the metal side, to increase the interfacial strength of co/cured metal-composite hybrid connections. In particular, Advanced Sheet Moulding Compound (ASMC) fibre carbon composite materials will be considered due to their good mechanical properties and suitability to be used for high production rate. The study will be carried out through an extensive experimental and numerical campaign aimed to: i) define the limit of the AM technology in producing the interfacial structure, ii) understand the capability of the composite material to wet and infiltrate the 3D interfacial structure during the manufacturing process as a function of technological and geometrical factors; iii) develop and assess numerical techniques capable of predicting the manufacturing process and the failure behaviour of hybrid joints; iv) test the developed technology into a component representing a real application of a hybrid metal-composite joint. Furthermore, to increase the reliability and sustainability of the developed connections, other two parts of the project will be devoted to: i) implement self-sensing health-monitoring capabilities into the hybrid connection to allow continuous monitoring of the joint integrity, preventing unnecessary oversizing as well as unexpected failure; ii) develop a disassembly method based on local heating of the metal part to allow the separation between the composite and the metal component, and the subsequent re-use of the latter. RESULTS ACHIEVED The results obtained within the project provide a solid basis for further developments of the proposed technology. The experimental and numerical activities carried out during the project have demonstrated the feasibility of using additively manufactured lattice structures to improve the mechanical performance of hybrid metal–composite joints and to introduce self-sensing capabilities for structural health monitoring. Future developments will focus on extending the investigation to more complex joint geometries and loading conditions. In particular the fracture and fatigue properties will be investigated by proper testing and numerical modelling. Indeed, the presence of lattice structures at the interface can enhance joint strength, but, at the same time, the presence of the same structure can induce manufacturing-related issues that may lead to non-uniform fibre distribution or the formation of voided regions, which can finally compromise the mechanical performance of the joint under more complex loading scenario. Therefore, a deeper investigation of the relationship between technological aspects of the manufacturing process and the mechanical behaviour of the joint is required, particularly under more complex loading conditions such as fatigue and fracture. Finally, the integration of the proposed sensing approach into practical monitoring systems represents a promising direction for future research, potentially enabling realtime detection of damage in hybrid structures. Overall, the project was successfully completed and the main objectives originally defined in the proposal were achieved. The research activities carried out by the participating units allowed a comprehensive investigation of the design, manufacturing and mechanical behaviour of hybrid metal–composite joints featuring interfacial lattice structures. The results obtained demonstrate the effectiveness of the proposed approach in enhancing joint performance and highlight the potential of combining advanced manufacturing techniques with composite processing technologies. The collaboration between the research units proved to be highly effective and enabled the integration of experimental and numerical approaches, leading to a deeper understanding of the underlying physical mechanisms governing the behaviour of the investigated joints. The outcomes of the project provide a solid scientific basis for future developments and potential industrial applications in sectors where lightweight hybrid structures are required.
Dettagli del progetto
Responsabile scientifico: Andrea Zucchelli
Strutture Unibo coinvolte:
Dipartimento di Ingegneria Industriale
Coordinatore:
Università degli Studi di PARMA(Italy)
Contributo totale Unibo: Euro (EUR) 115.320,00
Durata del progetto in mesi: 24
Data di inizio
28/09/2023
Data di fine:
28/02/2026
