Sanabria Sergio J, Baensch Franziska, Zauner Michaela, Niemz Peter
Zurich Ultrasound Research and Translation (ZURT), Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Raemistrasse 100, 8091, Zurich, Switzerland.
Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, 12205, Berlin, Germany.
Sci Rep. 2020 Dec 10;10(1):21615. doi: 10.1038/s41598-020-78028-4.
Wood-based composites hold the promise of sustainable construction. Understanding the influence on wood cellular microstructure in the macroscopic mechanical behavior is key for engineering high-performance composites. In this work, we report a novel Individual Cell Tracking (ICT) approach for in-situ quantification of nanometer-scale deformations of individual wood cells during mechanical loading of macroscopic millimeter-scale wood samples. Softwood samples containing > 10 cells were subjected to controlled radial tensile and longitudinal compressive load in a synchrotron radiation micro-computed tomography (SRµCT) setup. Tracheid and wood ray cells were automatically segmented, and their geometric variations were tracked during load. Finally, interactions between microstructure deformations (lumen geometry, cell wall thickness), cellular arrangement (annual growth rings, anisotropy, wood ray presence) with the macroscopic deformation response were investigated. The results provide cellular insight into macroscopic relations, such as anisotropic Poisson effects, and allow direct observation of previously suspected wood ray reinforcing effects. The method is also appropriate for investigation of non-linear deformation effects, such as buckling and deformation recovery after failure, and gives insight into less studied aspects, such as changes in lumen diameter and cell wall thickness during uniaxial load. ICT provides an experimental tool for direct validation of hierarchical mechanical models on real biological composites.
木质基复合材料具有可持续建筑的前景。了解木材细胞微观结构对宏观力学行为的影响是制造高性能复合材料的关键。在这项工作中，我们报告了一种新颖的个体细胞追踪（ICT）方法，用于在宏观毫米级木材样品的机械加载过程中对单个木材细胞的纳米级变形进行原位量化。在同步辐射微计算机断层扫描（SRµCT）装置中，对含有超过10个细胞的软木样品施加受控的径向拉伸和纵向压缩载荷。对管胞和木射线细胞进行自动分割，并在加载过程中跟踪它们的几何变化。最后，研究了微观结构变形（细胞腔几何形状、细胞壁厚度）、细胞排列（年轮、各向异性、木射线存在情况）与宏观变形响应之间的相互作用。结果为宏观关系（如各向异性泊松效应）提供了细胞层面的见解，并允许直接观察先前怀疑的木射线增强效应。该方法也适用于研究非线性变形效应，如屈曲和破坏后的变形恢复，并深入了解较少研究的方面，如单轴载荷下细胞腔直径和细胞壁厚度的变化。ICT为直接验证真实生物复合材料上的分层力学模型提供了一种实验工具。
