Toughness amplification in natural composites
Toughness amplification in natural composites
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DOI：
10.1016/j.jmps.2011.01.001
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发表时间：
2011-04-01
影响因子：
5.3
通讯作者：
Rabiei, Reza
中科院分区：
文献类型：
--
作者：
Barthelat, Francois;Rabiei, Reza
天然的结构材料，如骨头和贝壳，是由相对较弱的积木制成的，但它们表现出刚度，强度和韧性的显着组合。这种性能在很大程度上可以通过它们的“交错微观结构”来解释;高纵横比的刚性夹杂物彼此平行放置，并有一些重叠，并通过较软的基体结合。虽然交错复合材料的刚度和强度现在已经得到很好的理解，但断裂机制在很大程度上仍然是未知的。这是一个明显的缺陷，因为相对于其组分的韧性放大是迄今为止天然交错复合材料如珍珠层或骨中最令人印象深刻的特征。在这里，一个模型捕获的突出机制，在开裂的交错结构。我们表明，夹杂物和大的工艺区的拔出导致巨大的韧性远远超过单个组件。该模型还表明，像珍珠层这样的材料不能达到稳态开裂，这意味着韧性随着裂纹的发展而无限增加。这些研究结果与现有的断裂数据吻合良好，并首次将微观结构参数与整体韧性联系起来。这些见解将在仿生材料的设计中证明是有用的，并为纳米和微米尺度上的骨折提供线索。(C)2011爱思唯尔有限公司保留所有权利。
Natural structural materials such as bone and seashells are made of relatively weak building blocks, yet they exhibit remarkable combinations of stiffness, strength and toughness. This performance can be largely explained by their "staggered microstructure"; stiff inclusions of high aspect ratio are laid parallel to each other with some overlap, and bonded by a softer matrix. While stiffness and strength are now well understood for staggered composites, the mechanisms involved in fracture are still largely unknown. This is a significant lack since the amplification of toughness with respect to their components is by far the most impressive feature in natural staggered composites such as nacre or bone. Here a model capturing the salient mechanisms involved in the cracking of a staggered structure is presented. We show that the pullout of inclusions and large process zones lead to tremendous toughness by far exceeding that of individual components. The model also suggests that a material like nacre cannot reach steady state cracking, with the implication that the toughness increases indefinitely with crack advance. These findings agree well with existing fracture data, and for the first time relate microstructural parameters with overall toughness. These insights will prove useful in the design of biomimetic materials, and provide clues on how bone fractures at the nano and microscales. (C) 2011 Elsevier Ltd. All rights reserved.