Fiber-reinforced composites (FRCs) are hierarchical materials with a particular microstructure at the micro-(fibres organized into yarns, plies, or random mats within a matrix) and mesoscale (plies organized into laminates, yarns organized into a textile reinforcement). On the macroscale, the textiles or laminates are transformed into 3D-shaped parts. Applications of composites are driven by their macroscale thermo-mechanical and functional properties, especially by excellent weight-specific properties. The hierarchical nature of fibrous composites allows an intelligent design of the material on a lower scale and on a specific structural level.

For this, an XCT visualization of the fibrous composites is not enough. The design must be assisted with quantifying the visualized features and linking these features with the mechanical and functional performance. XCT opens two routes for this:

• Quantification of the microstructure, of the manufacturing defects and in-service damage. Examples of such quantification are fibre orientation distribution, size, shape, and spatial distribution of voids, matrix cracks, or fibre break density. The quantification results can be used for assigning local properties in FE models or serve as the basis for global performance predictions, or obtaining ranges of the material properties and their deterioration because of damage. When integrated with the design optimization process, the quantification results allow researchers to analyse and refine designs with a profound understanding of the material’s microstructure.
• Creation of a “digital twin” of the material, which reproduces the geometry of microstructural elements and defects with maximum possible precision; the XCT spatial resolution is among the factors limiting this precision. Thos is the basis for constructing mechanical and physical models (most often finite elements (FE)), which allow simulation of the in-service behaviour of the material and calculation of its performance, hence properties.

The talk is mainly based on the research conducted in the Department of Materials Engineering, KU Leuven, in collaboration with other groups worldwide, summarised in the book chapter: