鳄鱼皮及其他薄膜的破碎力学

Mechanics of fragmentation of crocodile skin and other thin films.

作者信息

Qin Zhao, Pugno Nicola M, Buehler Markus J

机构信息

1] Laboratory for Atomistic and Molecular Mechanics (LAMM), Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Room 1-239, Cambridge 02139, MA, USA [2] Center for Computational Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA.

1] Laboratory of Bio-Inspired & Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, Università di Trento, via Mesiano, 77 I-38123 Trento, Italy [2] Center for Materials and Microsystems, Fondazione Bruno Kessler, Via Sommarive 18, 38123 Povo (Trento) [3] School of Engineering & Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, UK.

出版信息

Sci Rep. 2014 May 27;4:4966. doi: 10.1038/srep04966.

DOI:10.1038/srep04966

PMID:24862190

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC4034009/

Abstract

Fragmentation of thin layers of materials is mediated by a network of cracks on its surface. It is commonly seen in dehydrated paintings or asphalt pavements and even in graphene or other two-dimensional materials, but is also observed in the characteristic polygonal pattern on a crocodile's head. Here, we build a simple mechanical model of a thin film and investigate the generation and development of fragmentation patterns as the material is exposed to various modes of deformation. We find that the characteristic size of fragmentation, defined by the mean diameter of polygons, is strictly governed by mechanical properties of the film material. Our result demonstrates that skin fragmentation on the head of crocodiles is dominated by that it features a small ratio between the fracture energy and Young's modulus, and the patterns agree well with experimental observations. Understanding this mechanics-driven process could be applied to improve the lifetime and reliability of thin film coatings by mimicking crocodile skin.

摘要

材料薄层的破碎是由其表面的裂纹网络介导的。这在脱水的绘画作品、沥青路面中很常见，甚至在石墨烯或其他二维材料中也能看到，而且在鳄鱼头部的特征多边形图案中也能观察到。在这里，我们构建了一个薄膜的简单力学模型，并研究了材料在受到各种变形模式时破碎图案的产生和发展。我们发现，由多边形平均直径定义的破碎特征尺寸严格受薄膜材料力学性能的控制。我们的结果表明，鳄鱼头部的皮肤破碎主要是因为其断裂能与杨氏模量的比值较小，并且这些图案与实验观察结果非常吻合。理解这个由力学驱动的过程可以通过模仿鳄鱼皮来提高薄膜涂层的寿命和可靠性。