Determination of the Young's modulus of silica aerogels – an analytical–numerical approach
Abstract
The superior thermal, optical, acoustical, and mechanical properties of a nano-porous and ultra-light material called silica aerogel have been known to science since the 1930's. In this study, we propose a new analytical–numerical model of a silica aerogel to predict its Young's modulus. The molecular dynamics (MD) simulation method was adopted to model and simulate the backbone of silica aerogels with different densities in an improved negative pressure rupturing method, and their mechanical properties were investigated. To generate the model using MD, the traditional method was improved by changing the sequence of its procedures, and it was proven to be a more stable and physically representative method. In the prediction, we proposed a two-level nano-porous structure model according to our simulations and the widely accepted fractal structure of silica aerogels. The Young's modulus of a silica aerogel, which is shown in a power–law relationship with the density of samples, was derived by the two-level hierarchical model and uniaxial tension tests. We envisage that this new model can be applied in more analytical–numerical studies to reveal other interesting mechanical properties of silica aerogels.
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