Using In Situ Synchrotron-Radiation-Based Microtomography to Investigate 3D Structure-Dependent Material Properties of Tension Wood

Abstract

Synchrotron-radiation-based microtomography enables the three-dimensional analysis of biological samples in situ beyond simple visualization, providing accurate measurements and recording of temporal data. The microtomography end station at P05 (PETRA III, Hamburg, Germany), operated by the Helmholtz Zentrum Hereon, can accommodate complex sample environments such as a load frame for mechanical testing. Here, we present the strain analysis of a volumetric time series dataset of small hardwood samples. For this in situ mechanical testing, the load frame was operated in tensile mode, and the biogenic material samples were subdivided into those specialized for tensile forces and those of regular anatomical structure. Digital volume correlation analysis allowed for the prediction of strain development at any position in the sample. The tissue specialized for tensile strength can align dislocations formed under tension such that the deformation is stronger and more ordered. Our results showed how high-resolution imaging of sequential loading and the subsequent localization of strain can reveal functional morphological relationships. These methods can be extended to other biological materials and may prove to be extremely relevant for the analyses of fibrous and/or layered composite materials.