Sol–gel simulation—II: Mechanical response

A novel computational procedure is proposed to predict the outstanding mechanical properties of sol–gel structures. An aggregation algorithm incorporating Brownian motion and chemical reactions is used to recreate the sol–gel structures at molecular scale. Just like in the physical colloidal aggregation process, the computational aggregation process produces structures with fractal features. Such fractal character leads to a recursion algorithm for calculating mechanical properties at any scale using a recursive multiscale approach. The mechanical properties are then predicted at each scale by calculating the effective properties using the Finite Element Method. It is shown that Youngʹs modulus naturally follows a power law relationship with density, whereas Poissonʹs ratio displays more complicated behavior. Also, it is shown that Youngʹs modulus and Poissonʹs ratio depend on a) the mass distribution of the structure, which is influenced by the Brownian motion and chemical reactivity during the aggregation process, and b) the connectivity, which is also influenced by additional processes as sintering and/or aging. Finally, it is shown that the Youngʹs modulus and Poissonʹs ratio can be correlated to scattering intensity of sintered and/or aged structures.