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Computer Simulation of Fracture in Aerogels

Published online by Cambridge University Press:  26 February 2011

Brian Good
Brian Good*
Affiliation:
Brian.Good@grc.nasa.gov, NASA Glenn Research Center, Materials and Structures Division, 21000 Brookpark Road, MS 106-5, Cleveland, OH, 44135, United States, 216-433-6296
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Abstract

Aerogels are of interest to the aerospace community primarily for their thermal properties, notably their low thermal conductivities. While the gels are typically fragile, recent advances in the application of conformal polymer layers to these gels has made them potentially useful as lightweight structural materials as well. In this work, we investigate the strength and fracture behavior of silica aerogels using a molecular statics-based computer simulation technique. The gels' structure is simulated via a Diffusion Limited Cluster Aggregation (DLCA) algorithm, which produces fractal structures representing experimentally observed aggregates of so-called secondary particles, themselves composed of amorphous silica primary particles an order of magnitude smaller. We have performed multi-length-scale simulations of fracture in silica aerogels, in which the interaction between two secondary particles is assumed to be described by a Morse pair potential parameterized such that the potential range is much smaller than the secondary particle size. These Morse parameters are obtained by atomistic simulation of models of the experimentally-observed amorphous silica “bridges,” with the fracture behavior of these bridges modeled via molecular statics using a Morse/Coulomb potential for silica. We consider the energetics of the fracture, and compare qualitative features of low-and high-density gel fracture.

Keywords

aerogelfracturesimulation
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 978: Symposium GG – Multiscale Modeling of Materials , 2006 , 0978-GG05-03
Copyright
Copyright © Materials Research Society 2007

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