Finite element modeling of the mechanical behavior of filamentary nanoporous materials

Abstract

Many natural organic and inorganic materials exhibit filamentary nanoporous structures which provide them with very interesting physical properties. With the rise of science, these interesting properties has led humankind to imitate nature and manufacture artificial materials with these characteristics for technological purposes. Given that there is and has been a huge interest in studying these structures and their derived properties, the main objective of this work is to carry out a two-dimensional finite element modeling in order to study the mechanical properties of filamentary nanoporous materials and to identify the characteristics of some of these material's observed 'softening behavior'.

A large deformation analysis tool, based on the two node continuum-based beam finite element formulation, is developed. A numerical analysis is performed, which identifies the tool's limits as well as determines adequate numerical parameters that grant valid approximations. Finally, the physical analysis of an assumed silica aerogel material is performed. This allowed to put in evidence, on one hand, a severe collapse phenomenon for lattices comprised of very thin beams, while on the other hand a more gradual softening for lattices comprised of thicker beams. One then identified that buckling plays an important role in the observed collapse/softening of these lattices. Resuming, one gathers all obtained results in one graph which plots the collapse/critical pressure with respect to lattices solidity fraction as given here below.