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Additive manufacturing (AM) unlocks novel industrial possibilities in relation to design optimisation for lightweight structures, e.g. in aerospace applications. However, the inherent geometric complexity of topology-optimised AM components represents a major challenge for conventional non-destructive testing (NDT) methods. Due to its flexibility and high throughput, industrial X-ray micro-computed tomography (XCT) is the most promising NDT method for AM. In this contribution, we investigate topology-optimised engine brackets that were manufactured from AlSi10 Mg using selective laser melting (SLM). We investigate the respective parts and in-process test coupons in a multiscale approach to be able to extract pore size distributions at different spatial resolutions between 105 and 1.25 µm isometric voxel size. At the lowest spatial resolutions, existing pores cannot be segmented. In contrast, decreasing voxel sizes leads to an increase in total porosity up to 1.53%. Defects like pores in load-carrying areas can profoundly influence the component´s mechanical performance; hence, extensive NDT investigations are mandatory to predict the effect of defects in aluminium AM components.

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In this work, we present a multimodal approach to three-dimensionally quantify and visualize fiber orientation and resin-rich areas in carbon-fiber-reinforced polymers manufactured by vacuum infusion. Three complementary image modalities were acquired by Talbot–Lau grating interferometer (TLGI) X-ray microcomputed tomography (XCT). Compared to absorption contrast (AC), TLGI-XCT provides enhanced contrast between polymer matrix and carbon fibers at lower spatial resolutions in the form of differential phase contrast (DPC) and dark-field contrast (DFC). Consequently, relatively thin layers of resin, effectively indiscernible from image noise in AC data, are distinguishable. In addition to the assessment of fiber orientation, the combination of DPC and DFC facilitates the quantification of resin-rich areas, e.g., in gaps between fiber layers or at binder yarn collimation sites. We found that resin-rich areas between fiber layers are predominantly developed in regions characterized by a pronounced curvature. In contrast, in-layer resin-rich areas are mainly caused by the collimation of fibers by binder yarn. Furthermore, void volume around two adjacent 90°-oriented fiber layers is increased by roughly 20% compared to a random distribution over the whole specimen.