Scientists from the DIAGONAL project, coordinated by Universidad Carlos III de Madrid (UC3M) and made up of ten European and American universities and research centres, are developing a new generation of functionally graded materials, which are those generally made up of different components (metals, ceramics, polymers, etc.) mixed using 3D printers. This type of technology, with applications in the air transport and security industries, will make it possible to obtain more efficient, sustainable and cheaper materials.
Functionally graded structures are made up of one or more materials that are combined using additive manufacturing techniques (such as 3D printing) in proportions that vary according to the space. Unlike composite materials (alloys consisting of a matrix and a reinforcement), at each point or zone the functionally graded structure exhibits different properties. "The aim is to get these structures to optimise their mechanical properties. For example, a material can be designed so that in a certain area it possesses better properties to support a certain mechanical load, because that area is where it will have to support a greater amount of weight or withstand an impact," explains Guadalupe Vadillo, head of the project at UC3M and a researcher in the university's Department of Continuum Mechanics and Structural Analysis.
Functionally graded materials are capable of withstanding large thermal increases, which makes them particularly suitable for the construction of an aircraft fuselage or for the different components of an engine (both aircraft and rocket). In addition, they can inhibit the propagation of cracks and fissures. This property makes them useful in defence applications, such as the development of materials that are more resistant to high-speed impacts in order to improve the performance of protective structures, according to the researchers. Interest in functionally graded materials is also growing in biomedical applications, such as bone implants made from these materials that achieve optimal mechanical behaviour with the desired bone biocompatibility. "These types of materials, due to their characteristics, are going to bring about a revolution in the field of structural engineering. We are going to achieve more efficient, sustainable and cheaper materials, because they tend to minimise production costs and times (eliminating excess material) and allow for the customisation of mechanical properties for specific applications," emphasised Guadalupe Vadillo.
UC3M researchers are going to focus on modelling the behaviour of these materials; specifically, in the development of the computational aspect that has to do with numerical simulations. This will serve as a basis so that other project partners can subsequently use this data to develop and optimise these materials.
There are now 3D printers that can print not only polymeric and metallic materials, but also ceramics. When it comes to combining several materials in the same structure, as investigated in this project, the main challenge relates to how to optimise the properties of these composites by combining the best characteristics of each material. The aim is to spatially vary the mechanical properties in such a way that the response of the structure to a given industrial application can be customised.
DIAGONAL (Ductility and Fracture Toughness analysis of functionally graded materials) is a Marie Sklodowska-Curie Actions (MSCA) Staff Exchanges (SE) project coordinated by UC3M (GA 101086342) that will run from 2023 to 2027. It involves ten universities and research centres: four European beneficiary institutions (UC3M and Universidad de Sevilla, in Spain; the Institute of Fundamental Technological Research, in Poland; and the IMT School for Advanced Studies Lucca, in Italy) together with six partner institutions: four from the United States (University of Florida, Northwestern University, Texas A&M University, University of Minnesota Twin Cities), one from Australia (Monash University) and one from Brazil (Universidade Federal de Santa Maria). The MSCA-SE projects aim to create networks to promote the exchange of knowledge between different universities and research centres at an international level by encouraging the mobility of its members through research stays and outreach activities (scientific conferences and symposia, courses, seminars, etc.).