Laboratory X-ray Imaging in Mechanics of Materials

Abstract

This habilitation thesis presents an in-depth exploration of various laboratory X-ray imaging methodologies employed in the research field of mechanics of materials. It encompasses a wide spectrum of techniques, from traditional axial radiography to advanced on-the-fly 4D computed microtomography, highlighting specialized approaches such as subtraction tomography and flash X-ray radiography. Each methodology is described including the respective imaging chains to illustrate the process of analyzing the behavior of the materials under different conditions in high detail on a volumetric basis. The thesis emphasizes the relevance of these imaging techniques in investigating critical factors that influence material mechanics, such as porosity, design fidelity, and the presence of water in binders. It discusses how these factors interact with the nature of the load applied during the experiments, which ultimately affects the performance of the material and its structural integrity. From a material science perspective, the thesis categorizes the X-ray imaging methods in relation to various types of studied materials. This includes biological materials, specifically natural bones, which serve as a benchmark to understand the structural complexity and biological function of skeletons. The research further extends to biomaterials, focusing on tissue scaffolds that are pivotal in regenerative medicine. In addition, the work examines civil engineering binder composites, such as natural rocks and cementitious materials, highlighting the importance of X-ray imaging in assessing material durability and performance. Finally, cellular engineeringmaterials in terms of metal foams are investigated to understand their mechanical properties and potential applications. In the concluding section, the thesis introduces advancements in high-speed microtomography, showcasing an innovative imaging chain integrated with a liquid metal anode X-ray source. This advancement facilitates the possibility of conducting timelapse imaging of transient events with micrometric resolution—capabilities that were previously confined to high-energy environments such as particle accelerators. The implications of this technology extend to numerous fields, paving the way for enhanced material characterization and the study of dynamic processes in materials science.