Institute of Solid Mechanics, School of Aeronautic Science and Engineering, Beihang University (BUAA), Beijing, 100083, PR China.
Institute of Solid Mechanics, School of Aeronautic Science and Engineering, Beihang University (BUAA), Beijing, 100083, PR China; Aircraft & Propulsion Laboratory, Ningbo Institute of Technology (NIT), Beihang University (BUAA), Ningbo, 315832, PR China.
J Mech Behav Biomed Mater. 2021 Jul;119:104442. doi: 10.1016/j.jmbbm.2021.104442. Epub 2021 Mar 16.
Due to the unique "Brick-and-Mortar" structure, nacre exhibits extraordinary mechanical properties such as high strength and toughness, which are naturally exclusive in traditional engineering materials. The main threat to the shell is the impact load along the direction perpendicular to the lamellar structure. However, how it attenuates stress wave and dissipates kinetic energy during impact events remains unclear, especially along different loading directions (the directions perpendicular and parallel to the lamellar structure). In this paper, damping performance of nacreous bio-inspired composites is investigated to evaluate the energy dissipation from the perspective of dynamic modulus using theoretical and numerical methods. It is found that the stress states and Poisson's ratio of the "mortar" exert remarkable influence on composites' loss modulus. Moreover, the predicted optimal aspect ratio in this work is consistent with the previously reported experimental observation. Additionally, by introducing interlocked structure, the composites show strong direction-dependent damping behaviors, and the enhanced loss modulus is observed both in longitudinal and normal direction. The findings are not only expected to achieve a deep understanding of the dynamic energy dissipation mechanism of nacre, but also to provide a guideline for design of bio-inspired composites responding to shock loads.
由于独特的“砖泥”结构，珍珠层表现出非凡的机械性能，如高强度和韧性，这在传统工程材料中是自然排斥的。贝壳的主要威胁是沿着与层状结构垂直的方向的冲击载荷。然而，它如何在冲击事件中衰减应力波和耗散动能仍然不清楚，特别是在不同的加载方向（垂直和平行于层状结构的方向）。本文通过理论和数值方法，从动态模量的角度研究了珍珠层仿生复合材料的阻尼性能，以评估其能量耗散。结果表明，“灰泥”的应力状态和泊松比对复合材料的损耗模量有显著影响。此外，本文预测的最佳纵横比与先前报道的实验观察结果一致。此外，通过引入互锁结构，复合材料表现出强烈的各向异性阻尼行为，在纵向和法向方向都观察到增强的损耗模量。这些发现不仅有望深入了解珍珠层的动态能量耗散机制，而且为设计应对冲击载荷的仿生复合材料提供了指导。
