School of Mechanical and Automotive Engineering, South China University of Technology, 510640 Guangzhou, China.
School of Mechanical and Automotive Engineering, South China University of Technology, 510640 Guangzhou, China.
J Mech Behav Biomed Mater. 2014 Aug;36:1-11. doi: 10.1016/j.jmbbm.2014.04.001. Epub 2014 Apr 13.
The structure-mechanical relationship of palm sheath is studied with numerical and experimental methods. The cellular structure of the vascular tissue is rebuilt with an image-based reconstruction method and used to create finite element models. The validity of the models is firstly verified with the results from the tensile tests. Then, the cell walls inside each of the specific regions (fiber cap, vessel, xylem, etc.) are randomly removed to obtain virtually imperfect structures. By comparing the magnitudes of performance degradation in the different imperfect structures, the influences of each region on the overall mechanical performances of the vascular tissue are discussed. The longitudinal stiffness and yield strength are sensitive to the defects in the vessel regions. While in the transverse directions (including the radial and tangential directions), the parenchymatous tissue determines the mechanical properties of the vascular tissue. Moreover, the hydraulic, dynamic response and energy absorption behavior of the vascular tissue are numerically explored. The flexibility of natural palm tissue enhances its impact resistance. Under the quasi-static compression, the cell walls connecting the fiber cap and the vessel dissipate more energy. The dominant role of the fiber cap in the plastic energy dissipation under high-speed impact is observed. And the radially-arranged fiber cap also allows the palm tissue to improve its tangential mechanical performances under hydraulic pressure.
采用数值和实验方法研究了掌状鞘的结构-力学关系。利用基于图像的重建方法重建维管束组织的细胞结构，并将其用于创建有限元模型。首先通过拉伸试验的结果验证了模型的有效性。然后，随机去除每个特定区域（纤维帽、导管、木质部等）内的细胞壁，以获得虚拟的不完美结构。通过比较不同不完美结构中性能下降的幅度，讨论了每个区域对维管束组织整体力学性能的影响。纵向刚度和屈服强度对导管区域的缺陷敏感。而在横向方向（包括径向和切向），薄壁组织决定了维管束组织的力学性能。此外，还对维管束组织的水力、动力响应和能量吸收行为进行了数值研究。天然掌状组织的柔韧性增强了其抗冲击能力。在准静态压缩下，连接纤维帽和导管的细胞壁耗散更多能量。观察到纤维帽在高速冲击下的塑性能量耗散中起主导作用。并且纤维帽的径向排列还使掌状组织能够在液压下提高其切向力学性能。
