In-situ CT of Viscoelastic Plastic Materials: A Radiography-Based Lead Time Determination for Composite–Metal Joints at Elevated Temperature Dargel, Alrik Troschitz, Juliane Gude, Maik Kupfer, Robert <jats:p>In-situ computed tomography (CT) experiments on materials with time-dependent mechanical behaviour are affected by relaxationinduced motion, which can lead to image blur and motion-related artefacts if scans are initiated before relaxation-induced motion has subsided. Scan start times are therefore commonly defined based on force relaxation or force-gradient criteria, although these signals do not directly quantify image-relevant specimen motion. In this work, a radiography-based approach is presented to estimate relaxation-induced motion via pixel shifts from projection images acquired prior to CT scans. These projection-based pixel shift estimates of relaxation-induced motion are related to scan-specific image blur observed in the reconstructed volumes. Thereby, a direct link between specimen motion during the scan and CT image quality is established. The method is demonstrated for thermo-mechanically loaded specimens with pronounced temperature-dependent material behaviour, where relaxation-induced motion persists over extended time scales. The results show that projection-based pixel shift estimation provides a physically meaningful and experimentally accessible basis for defining scan start criteria. CT acquisition can be initiated based on an allowable level of relaxation-induced motion, rather than waiting for mechanical equilibrium to be reached. The proposed approach therefore offers a direct, image-related framework for scan timing in in-situ CT experiments on time-dependent materials.</jats:p> NDT.net GmbH & Co. KG 2026 info:eu-repo/semantics/conferenceObject doc-type:conferenceObject text http://purl.org/coar/resource_type/c_5794 https://ris.uni-paderborn.de/record/65577 Dargel A, Troschitz J, Gude M, Kupfer R. In-situ CT of Viscoelastic Plastic Materials: A Radiography-Based Lead Time Determination for Composite–Metal Joints at Elevated Temperature. In: <i>E-Journal of Nondestructive Testing</i>. Vol 31. NDT.net GmbH &#38; Co. KG; 2026. doi:<a href="https://doi.org/10.58286/32601">10.58286/32601</a> eng info:eu-repo/semantics/altIdentifier/doi/10.58286/32601 info:eu-repo/semantics/altIdentifier/issn/1435-4934 info:eu-repo/semantics/closedAccess