Multiscale Modeling of Pore Collapse Instability in High-Porosity Solids

Abstract

High-porosity solids include elastomeric foams and other cellular materials, Aeolian sands, poorly cemented coquina, diatomite, and chalk. A majority of these materials are known to exhibit several regions of behavior in simple uniaxial or conventional triaxial compression: a nearly linearly elastic behavior at small strain, plastic behavior at larger strain, a plateau region in which strain increases at nearly constant stress, and, finally, a densification region characterized by pore collapse. In this paper we address the problem of pore collapse instability as a local bifurcation from a homogeneous solution driven by a singular constitutive tangent operator. We identify different eigenmodes (emodes) of bifurcation and propose an approach for constitutive branching useful for multiscale modeling of the pore collapse/densification process.