The detection of cracks in thermoplastic carbon fiber-reinforced polymer (CFRP) plates remains a major challenge for non-destructive testing (NDT) technologies. In particular, the planar nature of composite plates combined with the low contrast of fine crack structures complicates defect detection using conventional X-ray computed tomography (CT) or ultrasonic testing. In this contribution, we present an innovative application of X-ray computed laminography, combined with propagation-based phase-contrast enhancement, for the fast and reliable visualization of impact-induced cracks in thermoplastic CFRP.

Thermoplastic CFRP plates were subjected to controlled impact loading to induce sub-critical and critical crack structures. Traditional CT approaches were insufficient to resolve these cracks due to their orientation, planar extension, and extremely fine width, often below the voxel size of the scans. By employing computed laminography, we achieved layer-specific imaging with minimized geometric artifacts. Furthermore, phase-contrast effects were deliberately enhanced by optimizing the propagation distance between the sample and detector, significantly amplifying the visibility of crack edges and delaminations.

The experimental setup utilized a high-flux X-ray source and a large-area flat-panel detector, achieving effective voxel sizes down to 5 µm in laminographic mode. Acquisition parameters were fine-tuned to balance spatial resolution, phase contrast, and throughput, enabling a complete scan of critical plate regions within 30 minutes. The reconstructed data demonstrated that laminography, particularly when complemented by propagation-based phase-contrast imaging, markedly outperforms standard CT and ultrasound in detecting fine cracks and delaminations in flat CFRP structures.

This study highlights the transformative potential of advanced X-ray laminography for high-throughput inspection of thermoplastic CFRP components. The proposed method provides a new path forward for the aerospace and automotive industries, where fast, sensitive, and reliable NDT solutions are required for lightweight composite structures. The approach represents a step-change in NDT technology, enabling early detection of critical defects that were previously inaccessible to conventional inspection methods.