Mechanical properties
of aerogels are controlled by the connectivity
of their network. In this paper, in order to study these properties,
computational models of silica aerogels with different morphological
entities have been generated by means of the diffusion-limited cluster–cluster
aggregation (DLCA) algorithm. New insights into the influence of the
model parameters on the generated aerogel structures and on the finite
deformation under mechanical loads are provided. First, the structural
and fractal properties of the modeled aerogels are investigated. The
dependence of morphological properties such as the particle radius
and density on these properties is studied. The results are correlated
with experimental small-angle X-ray scattering (SAXS) data of a silica
aerogel. The DLCA models of silica aerogels are analyzed for their
mechanical properties with finite element simulations. There, the
aerogel particles are modeled as nodes and the interparticle bonds
as beam elements to account for bond stretching, bending, and torsion.
The scaling relation between the elastic moduli E and relative density ρ, E ∝ ρ
m
, is investigated and the exponent m = 3.61 is determined. Backbone paths evidently appear
in the 3-d network structure under deformation, while the majority
of the bonds in the network do not bear loads. The sensitivity of
particle neck-sizes on the mechanical properties is also studied.
All the results are shown to be qualitatively as well as quantitatively
in agreement with the experimental data or with the available literature.
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