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Received 22 July 2014; Revised 25 November 2014; Accepted 25 November 2014
Academic Editor: Libardo Vicente Vanegas Useche
Copyright © Xin-chun Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Auxetic honeycombs have proven to be an attractive advantage in actual engineering applications owing to their unique mechanical characteristic and better energy absorption ability.The in-plane dynamic crushing behaviors of the honeycombs with various cellwall angles are studied by means of explicit dynamic finite element simulation. The influences of the cell-wall angle, the impact velocity, and the edge thickness on the macro/microdeformation behaviors, the plateau stresses, and the specific energy absorption of auxetic honeycombs are discussed in detail.Numerical results show, that except for the impact velocity and the edge thickness, the in-plane dynamic performances of auxetic honeycombs also rely on the cell-wall angle.The "<>" -mode local deformation bands formunder low- ormoderate-velocity impacting, which results in lateral compression shrinkage and shows negative Poisson's ratio during the crushing. For the given impact velocity, the plateau stress at the proximal end and the energy-absorbed ability can be improved by increasing the negative cell angle, the relative density, the impact velocity, and the matrix material strength.When the microcell parameters are the constant, the plateau stresses are proportional to the square of impact velocity.
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1. Introduction
As one kind of new structural material with low weight, unique mechanical characteristics, and good design ability, auxetic honeycombs will be widely applied in aeronautics, electrical techniques, biomedical engineering, and military affairs. At present, the mechanical properties of these materials have attracted a great deal of attention at home and abroad [1-3]. Compared with conventional cellular materials, auxetic honeycombs are significantly different in terms of their internal structures and deformation mechanism. The mechanical responses of honeycombs are not just a base material behavior but are also determined by the local structure properties. Particularly in the dynamic crushing, auxetic honeycombs could show unique deformation behaviors and outstanding energy-absorbed characteristics [4, 5]. So how to establish the relations between cell internal structures and the dynamic crushing performance and further realize the self-design of auxetic honeycombs according to...