Monday, 11 October 2004 - 2:15 PM

This presentation is part of : Mechanics of Fiber Networks and Fibrous Materials

Dynamics and damage analysis of networks of randomly oriented nanofibers with the peridynamic method

Florin Bobaru, University of Nebraska-Lincoln, Assistant Professor, Department of Engineering Mechanics, W317.6 Nebraska Hall, Lincoln, NE 68588, Han Jiang, Department of Engineering Mechanics, University of Nebraska-Lincoln, Lincoln, NE 68588, and S. A. Silling, Sandia National Laboratories, Computational Physics Department, MS-0378, Albuquerque, NM 87185-0378.

The peridynamic method, which has been recently proposed by Dr. Silling, has great capabilities in capturing damage and dynamic fracture in three-dimensional settings as well as incorporate nano-scale effects at the discretization node level. In this paper we analyze the deformation, damage, and ultimate collapse of networks of continuous polymer fibers with diameters in the nanometer range. The extreme flexibility and large density of contacts of these novel materials (currently manufactured by Dr. Dzenis group in the Engineering Mechanics Department at University of Nebraska-Lincoln) promise unusual mechanical properties that we attempt to predict using the peridynamics model.

We generate nanofibers with random orientation in a thin three-dimensional box and perform displacement controlled numerical tests. From the manufacturing process of real fibers, some, but not all, of the fibers that come in contact are bonded. One question to be answered is how does the number of these bonded contacts influence the mechanical properties of the nanofiber membrane. We use a Monte Carlo approach to determine, for a given fraction of perfect bonds at the contact points between fibers, the influence on the ultimate strength of the membrane, damage patterns, and the membrane dynamic fracture behavior. Van der Waals forces between fibers are included in our model and we notice significant differences with the case when these forces are absent. Based on these results, we can suggest possible avenues for optimal design of nanofiber networks.

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